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T1021.004 SSH

Adversaries may use Valid Accounts to log into remote machines using Secure Shell (SSH). The adversary may then perform actions as the logged-on user.

SSH is a protocol that allows authorized users to open remote shells on other computers. Many Linux and macOS versions come with SSH installed by default, although typically disabled until the user enables it. The SSH server can be configured to use standard password authentication or public-private keypairs in lieu of or in addition to a password. In this authentication scenario, the user’s public key must be in a special file on the computer running the server that lists which keypairs are allowed to login as that user.

Item Value
ID T1021.004
Sub-techniques T1021.001, T1021.002, T1021.003, T1021.004, T1021.005, T1021.006, T1021.007
Tactics TA0008
Platforms Linux, macOS
Version 1.1
Created 11 February 2020
Last Modified 30 March 2023

Procedure Examples

ID Name Description
G0087 APT39 APT39 used secure shell (SSH) to move laterally among their targets.11
G0098 BlackTech BlackTech has used Putty for remote access.15
S0154 Cobalt Strike Cobalt Strike can SSH to a remote service.45
S0363 Empire Empire contains modules for executing commands over SSH as well as in-memory VNC agent injection.2
G0046 FIN7 FIN7 has used SSH to move laterally through victim environments.10
G0117 Fox Kitten Fox Kitten has used the PuTTY and Plink tools for lateral movement.16
G0036 GCMAN GCMAN uses Putty for lateral movement.18
S0599 Kinsing Kinsing has used SSH for lateral movement.3
G0032 Lazarus Group Lazarus Group used SSH and the PuTTy PSCP utility to gain access to a restricted segment of a compromised network.14
G0065 Leviathan Leviathan used ssh for internal reconnaissance.6
G0045 menuPass menuPass has used Putty Secure Copy Client (PSCP) to transfer data.7
G0049 OilRig OilRig has used Putty to access compromised systems.8
G0106 Rocke Rocke has spread its coinminer via SSH.9
G0139 TeamTNT TeamTNT has used SSH to connect back to victim machines.13 TeamTNT has also used SSH to transfer tools and payloads onto victim hosts and execute them.12
G0088 TEMP.Veles TEMP.Veles has relied on encrypted SSH-based tunnels to transfer tools and for remote command/program execution.17

Mitigations

ID Mitigation Description
M1042 Disable or Remove Feature or Program Disable the SSH daemon on systems that do not require it. For macOS ensure Remote Login is disabled under Sharing Preferences.1
M1032 Multi-factor Authentication Require multi-factor authentication for SSH connections wherever possible, such as password protected SSH keys.
M1018 User Account Management Limit which user accounts are allowed to login via SSH.

Detection

ID Data Source Data Component
DS0028 Logon Session Logon Session Creation
DS0029 Network Traffic Network Connection Creation
DS0009 Process Process Creation

References

  1. Sarah Edwards. (2020, April 30). Analysis of Apple Unified Logs: Quarantine Edition [Entry 6] – Working From Home? Remote Logins. Retrieved August 19, 2021. ↩

  2. Schroeder, W., Warner, J., Nelson, M. (n.d.). Github PowerShellEmpire. Retrieved April 28, 2016. ↩

  3. Singer, G. (2020, April 3). Threat Alert: Kinsing Malware Attacks Targeting Container Environments. Retrieved April 1, 2021. ↩

  4. Cobalt Strike. (2017, December 8). Tactics, Techniques, and Procedures. Retrieved December 20, 2017. ↩

  5. Strategic Cyber LLC. (2020, November 5). Cobalt Strike: Advanced Threat Tactics for Penetration Testers. Retrieved April 13, 2021. ↩

  6. Plan, F., et al. (2019, March 4). APT40: Examining a China-Nexus Espionage Actor. Retrieved March 18, 2019. ↩

  7. PwC and BAE Systems. (2017, April). Operation Cloud Hopper. Retrieved April 5, 2017. ↩

  8. Unit42. (2016, May 1). Evasive Serpens Unit 42 Playbook Viewer. Retrieved February 6, 2023. ↩

  9. Anomali Labs. (2019, March 15). Rocke Evolves Its Arsenal With a New Malware Family Written in Golang. Retrieved April 24, 2019. ↩

  10. Loui, E. and Reynolds, J. (2021, August 30). CARBON SPIDER Embraces Big Game Hunting, Part 1. Retrieved September 20, 2021. ↩

  11. Hawley et al. (2019, January 29). APT39: An Iranian Cyber Espionage Group Focused on Personal Information. Retrieved February 19, 2019. ↩

  12. Darin Smith. (2022, April 21). TeamTNT targeting AWS, Alibaba. Retrieved August 4, 2022. ↩

  13. Fishbein, N. (2020, September 8). Attackers Abusing Legitimate Cloud Monitoring Tools to Conduct Cyber Attacks. Retrieved September 22, 2021. ↩

  14. Vyacheslav Kopeytsev and Seongsu Park. (2021, February 25). Lazarus targets defense industry with ThreatNeedle. Retrieved October 27, 2021. ↩

  15. Threat Intelligence. (2020, September 29). Palmerworm: Espionage Gang Targets the Media, Finance, and Other Sectors. Retrieved March 25, 2022. ↩

  16. CISA. (2020, September 15). Iran-Based Threat Actor Exploits VPN Vulnerabilities. Retrieved December 21, 2020. ↩

  17. Miller, S, et al. (2019, April 10). TRITON Actor TTP Profile, Custom Attack Tools, Detections, and ATT&CK Mapping. Retrieved April 16, 2019. ↩

  18. Kaspersky Lab’s Global Research & Analysis Team. (2016, February 8). APT-style bank robberies increase with Metel, GCMAN and Carbanak 2.0 attacks. Retrieved April 20, 2016. ↩