Linux Restricted Shell Breakout via the expect command
editLinux Restricted Shell Breakout via the expect command
editIdentifies Linux binary expect command abuse to break out from restricted environments by spawning an interactive system shell. The expect utility allows us to automate control of interactive applications such as Telnet, FTP, SSH and others. The activity of spawning shell is not a standard use of this binary for a user or system administrator and could potentially indicate malicious actor attempting to improve the capabilities or stability of their access.
Rule type: eql
Rule indices:
- logs-endpoint.events.*
Severity: medium
Risk score: 47
Runs every: 5m
Searches indices from: now-9m (Date Math format, see also Additional look-back time)
Maximum alerts per execution: 100
References:
Tags:
- Elastic
- Host
- Linux
- Threat Detection
- Execution
- GTFOBins
Version: 2
Rule authors:
- Elastic
Rule license: Elastic License v2
Rule query
editprocess where event.type == "start" and process.name in ("bash", "sh", "dash") and
process.parent.name == "expect" and process.parent.args == "-c" and
process.parent.args in ("spawn /bin/sh;interact", "spawn /bin/bash;interact", "spawn /bin/dash;interact", "spawn sh;interact", "spawn bash;interact", "spawn dash;interact")
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
-
Technique:
- Name: Command and Scripting Interpreter
- ID: T1059
- Reference URL: https://attack.mitre.org/techniques/T1059/
-
Sub-technique:
- Name: Unix Shell
- ID: T1059.004
- Reference URL: https://attack.mitre.org/techniques/T1059/004/