Enumeration of Privileged Local Groups Membership

Elastic Stack Serverless Security

Identifies instances of an unusual process enumerating built-in Windows privileged local groups membership like Administrators or Remote Desktop users.

Rule type: eql

Rule indices:

• winlogbeat-*
• logs-system.*

Severity: medium

Risk score: 43

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: 100

References: None

Tags:

• Elastic
• Host
• Windows
• Threat Detection
• Discovery

Version: 3

Rule authors:

• Elastic

Rule license: Elastic License v2

This will require Windows security event 4799 by enabling audit success for the Windows Account Management category and
the Security Group Management subcategory.

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define event.ingested and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate event.ingested to @timestamp for this rule to work.

iam where event.action == "user-member-enumerated" and

 /* noisy and usual legit processes excluded */
 not winlog.event_data.CallerProcessName:
              ("?:\\Windows\\System32\\VSSVC.exe",
               "?:\\Windows\\System32\\SearchIndexer.exe",
               "?:\\Windows\\System32\\CompatTelRunner.exe",
               "?:\\Windows\\System32\\oobe\\msoobe.exe",
               "?:\\Windows\\System32\\net1.exe",
               "?:\\Windows\\System32\\svchost.exe",
               "?:\\Windows\\System32\\Netplwiz.exe",
               "?:\\Windows\\System32\\msiexec.exe",
               "?:\\Windows\\System32\\CloudExperienceHostBroker.exe",
               "?:\\Windows\\System32\\wbem\\WmiPrvSE.exe",
               "?:\\Windows\\System32\\SrTasks.exe",
               "?:\\Windows\\System32\\lsass.exe",
               "?:\\Windows\\System32\\diskshadow.exe",
               "?:\\Windows\\System32\\dfsrs.exe",
               "?:\\Program Files\\*.exe",
               "?:\\Program Files (x86)\\*.exe") and
  /* privileged local groups */
 (group.name:("admin*","RemoteDesktopUsers") or
  winlog.event_data.TargetSid:("S-1-5-32-544","S-1-5-32-555"))

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Discovery
  • ID: TA0007
  • Reference URL: https://attack.mitre.org/tactics/TA0007/

• Technique:

  • Name: Permission Groups Discovery
  • ID: T1069
  • Reference URL: https://attack.mitre.org/techniques/T1069/

• Sub-technique:

  • Name: Local Groups
  • ID: T1069.001
  • Reference URL: https://attack.mitre.org/techniques/T1069/001/