Setuid / Setgid Bit Set via chmod

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 (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

edit

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&CK^TM

Tactic:
- Name: Privilege Escalation
- ID: TA0004
- Reference URL: https://attack.mitre.org/tactics/TA0004/
Technique:
- Name: Abuse Elevation Control Mechanism
- ID: T1548
- Reference URL: https://attack.mitre.org/techniques/T1548/
Sub-technique:
- Name: Setuid and Setgid
- ID: T1548.001
- Reference URL: https://attack.mitre.org/techniques/T1548/001/
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/

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