Linux Restricted Shell Breakout via env Shell Evasionedit
Identifies Linux binary env abuse to break out from restricted environments by spawning an interactive system shell. The env utility is a shell command for Unix-like operating systems and is used to print a list of environment variables. The activity of spawning a shell is not a standard use of this binary for a user or system administrator. It indicates a potentially 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: 5 minutes
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: 1
Added (Elastic Stack release): 8.2.0
Rule authors: Elastic
Rule license: Elastic License v2
Rule queryedit
process where event.type == "start" and process.name : "env" and process.args_count == 2 and process.args : ("/bin/sh", "/bin/bash", "sh", "bash")
Threat mappingedit
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/