Linux Restricted Shell Breakout via env Shell Evasion
editLinux Restricted Shell Breakout via env Shell Evasion
editIdentifies 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 query
editprocess where event.type == "start" and process.name : "env" and
process.args_count == 2 and process.args : ("/bin/sh", "/bin/bash",
"sh", "bash")
Threat mapping
editFramework: 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/