Linux Restricted Shell Breakout via env Shell Evasion

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Linux Restricted Shell Breakout via env Shell Evasion

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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 OS which is used to print a list of environment variables and the activity of spawning 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: 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: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule query

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process where event.type == "start" and process.name : "env" and process.args_count == 2 and process.args : ("/bin/sh", "/bin/bash", "sh", "bash")

Framework: MITRE ATT&CKTM