Cross-source coverage
T1563.001 / ATT&CK
Remote Service Session Hijacking: SSH Hijacking
10 rules across 2 sources.
From MITRE ATT&CK 19.2
Adversaries may hijack a legitimate user's SSH session to move laterally within an environment. Secure Shell (SSH) is a standard means of remote access on Linux and macOS systems. It allows a user to connect to another system via an encrypted tunnel, commonly authenticating through a password, certificate or the use of an asymmetric encryption key pair.
In order to move laterally from a compromised host, adversaries may take advantage of trust relationships established with other systems via public key authentication in active SSH sessions by hijacking an existing connection to another system. This may occur through compromising the SSH agent itself or by having access to the agent's socket. If an adversary is able to obtain root access, then hijacking SSH sessions is likely trivial.
SSH Hijacking differs from use of SSH because it hijacks an existing SSH session rather than creating a new session using Valid Accounts.
- Tactics
- Lateral Movement
- Platforms
- Linux · macOS
- Telemetry
-
auditd:SYSCALLauditd:EXECVENSM:Connectionsmacos:unifiedlog
How MITRE says to detect it DET0256
Detection Strategy for SSH Session Hijacking
Linux Analytic 0710
Suspicious reuse of SSH agent sockets across multiple users or processes, anomalous access to ~/.ssh/ or /tmp/ssh-* sockets, and abnormal patterns of lateral movement via SSH without new authentication events. Defender view: detect when one process accesses another user's SSH agent or when an existing SSH connection is used to pivot unexpectedly.
auditd:SYSCALLopen or connect syscalls on /tmp/ssh-* or $SSH_AUTH_SOCKauditd:EXECVEExecution of ssh/scp/sftp without corresponding authentication logNSM:ConnectionsMissing new login event but session activity continues
macOS Analytic 0711
Unusual access to SSH agent sockets in /tmp/ or /private/tmp, process access to another user’s $SSH_AUTH_SOCK, and lateral SSH activity without corresponding login events. Defender view: correlation of socket access with anomalous network flows to internal systems.
macos:unifiedlogProcess opening SSH_AUTH_SOCK or /tmp/ssh-* socket not owned by same UIDmacos:unifiedlogExecution of ssh or sftp without corresponding login eventmacos:unifiedlogSession reuse without new auth event
elastic/detection-rules
8 rules| Detection | Severity | Format |
|---|---|---|
| Potential THC Tool Downloaded | High | Elastic TOML |
| Network Connection Initiated by Suspicious SSHD Child Process | Medium | Elastic TOML |
| Potential Execution via SSH Backdoor | Medium | Elastic TOML |
| SSH Authorized Key File Activity Detected via Defend for Containers | Medium | Elastic TOML |
| SSH Authorized Keys File Activity | Medium | Elastic TOML |
| Renaming of OpenSSH Binaries | Low | Elastic TOML |
| SSH Key Generated via ssh-keygen | Low | Elastic TOML |
| Unusual SSHD Child Process | Low | Elastic TOML |
elastic/protections-artifacts
2 rules| Detection | Severity | Format |
|---|---|---|
| Potential HackersChoice Tool Downloaded | Undefined | Elastic TOML |
| Unusual SSH Parent/Child Execution | Undefined | Elastic TOML |