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Setuid / Setgid Bit Set via chmod

Elastic Stack Serverless Security

An adversary may add the setuid or setgid bit to a file or directory in order to run a file with the privileges of the owning user or group. An adversary can take advantage of this to either do a shell escape or exploit a vulnerability in an application with the setuid or 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: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 33

References: None

Tags:

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

Version: 101

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule query

event.category:process AND event.type:(start OR process_started) AND
 process.name:chmod AND process.args:("+s" OR "u+s" OR /4[0-9]{3}/ OR g+s OR /2[0-9]{3}/) AND
 NOT process.args:
           (
             /.*\/Applications\/VirtualBox.app\/.+/ OR
             /\/usr\/local\/lib\/python.+/ OR
             /\/var\/folders\/.+\/FP.*nstallHelper/ OR
             /\/Library\/Filesystems\/.+/ OR
             /\/usr\/lib\/virtualbox\/.+/ OR
             /\/Library\/Application.*/ OR
             "/run/postgresql" OR
             "/var/crash" OR
             "/var/run/postgresql" OR
             /\/usr\/bin\/.+/ OR /\/usr\/local\/share\/.+/ OR
             /\/Applications\/.+/ OR /\/usr\/libexec\/.+/ OR
             "/var/metrics" OR /\/var\/lib\/dpkg\/.+/ OR
             /\/run\/log\/journal\/.*/ OR
             \/Users\/*\/.minikube\/bin\/docker-machine-driver-hyperkit
           ) AND
 NOT process.parent.executable:
           (
             /\/var\/lib\/docker\/.+/ OR
             "/System/Library/PrivateFrameworks/PackageKit.framework/Versions/A/XPCServices/package_script_service.xpc/Contents/MacOS/package_script_service" OR
             "/var/lib/dpkg/info/whoopsie.postinst"
           )

Framework: MITRE ATT&CKTM