Linux Restricted Shell Breakout via c89/c99 Shell evasionedit

Identifies Linux binary c89/c99 abuse to break out from restricted environments by spawning an interactive system shell.The c89/c99 utility is an interface to the standard C compilation system 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:


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



  • Elastic
  • Host
  • Linux
  • Threat Detection
  • Execution
  • GTFOBins

Version: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule queryedit

process where event.type == "start" and in ("sh", "dash", "bash") and in ("c89","c99") and process.parent.args == "-wrapper" and
  process.parent.args in ("sh,-s", "bash,-s", "dash,-s", "/bin/sh,-s", "/bin/bash,-s", "/bin/dash,-s")