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GoldMax

GoldMax is a second-stage C2 backdoor written in Go with Windows and Linux variants that are nearly identical in functionality. GoldMax was discovered in early 2021 during the investigation into the SolarWinds Compromise, and has likely been used by APT29 since at least mid-2019. GoldMax uses multiple defense evasion techniques, including avoiding virtualization execution and masking malicious traffic.[1][2][3]

ID: S0588
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Associated Software: SUNSHUTTLE
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Type: MALWARE
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Platforms: Windows, Linux
Version: 2.3
Created: 12 March 2021
Last Modified: 11 April 2024
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Associated Software Descriptions

Name Description
SUNSHUTTLE

[2]
Enterprise Layer
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Techniques Used

Domain ID Name Use
Enterprise T1071 .001 Application Layer Protocol: Web Protocols

GoldMax has used HTTPS and HTTP GET requests with custom HTTP cookies for C2.[1][2]
Enterprise T1059 .003 Command and Scripting Interpreter: Windows Command Shell

GoldMax can spawn a command shell, and execute native commands.[1][2]
Enterprise T1001 .001 Data Obfuscation: Junk Data

GoldMax has used decoy traffic to surround its malicious network traffic to avoid detection.[1]
Enterprise T1140 Deobfuscate/Decode Files or Information

GoldMax has decoded and decrypted the configuration file when executed.[1][2]
Enterprise T1573 .002 Encrypted Channel: Asymmetric Cryptography

GoldMax has RSA-encrypted its communication with the C2 server.[1]
Enterprise T1041 Exfiltration Over C2 Channel

GoldMax can exfiltrate files over the existing C2 channel.[1][2]
Enterprise T1564 .011 Hide Artifacts: Ignore Process Interrupts

The GoldMax Linux variant has been executed with the nohup command to ignore hangup signals and continue to run if the terminal session was terminated.[3]
Enterprise T1105 Ingress Tool Transfer

GoldMax can download and execute additional files.[1][2]
Enterprise T1036 .004 Masquerading: Masquerade Task or Service

GoldMax has impersonated systems management software to avoid detection.[1]
.005 Masquerading: Match Legitimate Name or Location

GoldMax has used filenames that matched the system name, and appeared as a scheduled task impersonating systems management software within the corresponding ProgramData subfolder.[1][3]
Enterprise T1027 .002 Obfuscated Files or Information: Software Packing

GoldMax has been packed for obfuscation.[2]
.013 Obfuscated Files or Information: Encrypted/Encoded File

GoldMax has written AES-encrypted and Base64-encoded configuration files to disk.[1][2]
Enterprise T1053 .003 Scheduled Task/Job: Cron

The GoldMax Linux variant has used a crontab entry with a @reboot line to gain persistence.[3]
.005 Scheduled Task/Job: Scheduled Task

GoldMax has used scheduled tasks to maintain persistence.[1]
Enterprise T1016 System Network Configuration Discovery

GoldMax retrieved a list of the system's network interface after execution.[1]
Enterprise T1124 System Time Discovery

GoldMax can check the current date-time value of the compromised system, comparing it to the hardcoded execution trigger and can send the current timestamp to the C2 server.[1][2]

Enterprise T1497 .001 Virtualization/Sandbox Evasion: System Checks

GoldMax will check if it is being run in a virtualized environment by comparing the collected MAC address to c8:27:cc:c2:37:5a.[1][2]
.003 Virtualization/Sandbox Evasion: Time Based Evasion

GoldMax has set an execution trigger date and time, stored as an ASCII Unix/Epoch time value.[1]

Groups That Use This Software

ID Name References
G0016 APT29

[1][4][5][6][7][8][9][10]

Campaigns

ID Name Description
C0024 SolarWinds Compromise

[1]

References

  1. Nafisi, R., Lelli, A. (2021, March 4). GoldMax, GoldFinder, and Sibot: Analyzing NOBELIUM’s layered persistence. Retrieved March 8, 2021.
  2. Smith, L., Leathery, J., Read, B. (2021, March 4). New SUNSHUTTLE Second-Stage Backdoor Uncovered Targeting U.S.-Based Entity; Possible Connection to UNC2452. Retrieved March 12, 2021.
  3. CrowdStrike. (2022, January 27). Early Bird Catches the Wormhole: Observations from the StellarParticle Campaign. Retrieved February 7, 2022.
  4. NCSC, CISA, FBI, NSA. (2021, May 7). Further TTPs associated with SVR cyber actors. Retrieved July 29, 2021.
  5. Microsoft Threat Intelligence Center (MSTIC). (2021, May 27). New sophisticated email-based attack from NOBELIUM. Retrieved May 28, 2021.
  1. MSTIC. (2021, May 28). Breaking down NOBELIUM’s latest early-stage toolset. Retrieved August 4, 2021.
  2. Secureworks CTU. (n.d.). IRON RITUAL. Retrieved February 24, 2022.
  3. NSA, FBI, DHS. (2021, April 15). Russian SVR Targets U.S. and Allied Networks. Retrieved April 16, 2021.
  4. UK NCSC. (2021, April 15). UK and US call out Russia for SolarWinds compromise. Retrieved April 16, 2021.
  5. Mandiant. (2020, April 27). Assembling the Russian Nesting Doll: UNC2452 Merged into APT29. Retrieved March 26, 2023.