Setgid Bit Set via chmod

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An adversary may add the setgid bit to a file or directory in order to run a file with the privileges of the owning group. An adversary can take advantage of this to either do a shell escape or exploit a vulnerability in an application with the setgid bit to get code running in a different user’s context. Additionally, adversaries can use this mechanism on their own malware to make sure they’re able to execute in elevated contexts in the future.

Rule type: query

Rule indices:

  • auditbeat-*
  • logs-endpoint.events.*

Severity: low

Risk score: 21

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 33

Tags:

  • Elastic
  • Host
  • Linux
  • Threat Detection
  • Privilege Escalation

Version: 4 (version history)

Added (Elastic Stack release): 7.8.0

Last modified (Elastic Stack release): 7.10.0

Rule authors: Elastic

Rule license: Elastic License

Rule query

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event.category:process AND event.type:(start or process_started) AND
process.name:chmod AND process.args:(g+s OR /2[0-9]{3}/) AND NOT
user.name:root

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 4 (7.10.0 release)
  • Formatting only
Version 3 (7.9.1 release)
  • Formatting only
Version 2 (7.9.0 release)
  • Updated query, changed from:

    event.action:(executed OR process_started) AND process.name:chmod AND
    process.args:(g+s OR /2[0-9]{3}/) AND NOT user.name:root