Linux Restricted Shell Breakout via busybox Shell Evasion

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Linux Restricted Shell Breakout via busybox Shell Evasion

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Identifies Linux binary busybox abuse to break out from restricted environments by spawning an interactive system shell.The busybox is software utility suite that provides several Unix utilities in a single executable file and the activity of spawing a shell is not a standard use of this binary by 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 == "busybox" and process.args_count == 2 and process.args in ("/bin/sh", "/bin/ash", "sh", "ash")

Framework: MITRE ATT&CKTM