Enumeration of Privileged Local Groups Membership

  1[metadata]
  2creation_date = "2020/10/15"
  3integration = ["system", "windows"]
  4maturity = "production"
  5updated_date = "2026/05/04"
  6
  7[transform]
  8[[transform.osquery]]
  9label = "Osquery - Retrieve DNS Cache"
 10query = "SELECT * FROM dns_cache"
 11
 12[[transform.osquery]]
 13label = "Osquery - Retrieve All Services"
 14query = "SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services"
 15
 16[[transform.osquery]]
 17label = "Osquery - Retrieve Services Running on User Accounts"
 18query = """
 19SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services WHERE
 20NOT (user_account LIKE '%LocalSystem' OR user_account LIKE '%LocalService' OR user_account LIKE '%NetworkService' OR
 21user_account == null)
 22"""
 23
 24[[transform.osquery]]
 25label = "Osquery - Retrieve Service Unsigned Executables with Virustotal Link"
 26query = """
 27SELECT concat('https://www.virustotal.com/gui/file/', sha1) AS VtLink, name, description, start_type, status, pid,
 28services.path FROM services JOIN authenticode ON services.path = authenticode.path OR services.module_path =
 29authenticode.path JOIN hash ON services.path = hash.path WHERE authenticode.result != 'trusted'
 30"""
 31
 32
 33[rule]
 34author = ["Elastic"]
 35description = """
 36Identifies instances of an unusual process enumerating built-in Windows privileged local groups membership like
 37Administrators or Remote Desktop users.
 38"""
 39from = "now-9m"
 40index = ["winlogbeat-*", "logs-system.security*", "logs-windows.forwarded*"]
 41language = "kuery"
 42license = "Elastic License v2"
 43name = "Enumeration of Privileged Local Groups Membership"
 44note = """## Triage and analysis
 45
 46### Investigating Enumeration of Privileged Local Groups Membership
 47
 48After successfully compromising an environment, attackers may try to gain situational awareness to plan their next steps. This can happen by running commands to enumerate network resources, users, connections, files, and installed security software.
 49
 50This rule looks for the enumeration of privileged local groups' membership by suspicious processes, and excludes known legitimate utilities and programs installed. Attackers can use this information to decide the next steps of the attack, such as mapping targets for credential compromise and other post-exploitation activities.
 51
 52> **Note**:
 53> This investigation guide uses the [Osquery Markdown Plugin](https://www.elastic.co/guide/en/security/current/invest-guide-run-osquery.html) introduced in Elastic Stack version 8.5.0. Older Elastic Stack versions will display unrendered Markdown in this guide.
 54
 55#### Possible investigation steps
 56
 57- Identify the process, host and user involved on the event.
 58- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
 59- Investigate other alerts associated with the user/host during the past 48 hours.
 60- Investigate any abnormal account behavior, such as command executions, file creations or modifications, and network connections.
 61- Examine the host for derived artifacts that indicate suspicious activities:
 62  - Analyze the process executable using a private sandboxed analysis system.
 63  - Observe and collect information about the following activities in both the sandbox and the alert subject host:
 64    - Attempts to contact external domains and addresses.
 65      - Use the Elastic Defend network events to determine domains and addresses contacted by the subject process by filtering by the process' `process.entity_id`.
 66      - Examine the DNS cache for suspicious or anomalous entries.
 67        - $osquery_0
 68    - Use the Elastic Defend registry events to examine registry keys accessed, modified, or created by the related processes in the process tree.
 69    - Examine the host services for suspicious or anomalous entries.
 70      - $osquery_1
 71      - $osquery_2
 72      - $osquery_3
 73  - Retrieve the files' SHA-256 hash values using the PowerShell `Get-FileHash` cmdlet and search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.
 74- Investigate potentially compromised accounts. Analysts can do this by searching for login events (for example, 4624) to the target host after the registry modification.
 75
 76### False positive analysis
 77
 78- Discovery activities are not inherently malicious if they occur in isolation. As long as the analyst did not identify suspicious activity related to the user or host, such alerts can be dismissed.
 79- If this rule is noisy in your environment due to expected activity, consider adding exceptions — preferably with a combination of user and command line conditions.
 80
 81### Response and remediation
 82
 83- Initiate the incident response process based on the outcome of the triage.
 84- Isolate the involved hosts to prevent further post-compromise behavior.
 85- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services.
 86- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
 87- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
 88- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
 89"""
 90risk_score = 47
 91rule_id = "291a0de9-937a-4189-94c0-3e847c8b13e4"
 92setup = """## Setup
 93
 94Audit Security Group Management must be enabled to generate the events used by this rule.
 95Setup instructions: https://ela.st/audit-security-group-management
 96"""
 97severity = "medium"
 98tags = [
 99    "Domain: Endpoint",
100    "OS: Windows",
101    "Use Case: Threat Detection",
102    "Tactic: Discovery",
103    "Resources: Investigation Guide",
104    "Data Source: Windows Security Event Logs",
105]
106timestamp_override = "event.ingested"
107type = "new_terms"
108
109query = '''
110host.os.type:windows and event.category:iam and event.action:user-member-enumerated and 
111  (
112    group.name:(*Admin* or "RemoteDesktopUsers") or
113    winlog.event_data.TargetSid:("S-1-5-32-544" or "S-1-5-32-555")
114  ) and 
115  not (
116    winlog.event_data.SubjectUserName: *$ or
117    winlog.event_data.SubjectUserSid: ("S-1-5-19" or "S-1-5-20") or 
118    winlog.event_data.CallerProcessName:("-" or 
119                                       C\:\\Windows\\System32\\VSSVC.exe or 
120                                       C\:\\Windows\\System32\\SearchIndexer.exe or 
121                                       C\:\\Windows\\System32\\CompatTelRunner.exe or 
122                                       C\:\\Windows\\System32\\oobe\\msoobe.exe or
123                                       C\:\\Windows\\System32\\net1.exe or 
124                                       C\:\\Windows\\System32\\svchost.exe or 
125                                       C\:\\Windows\\System32\\Netplwiz.exe or 
126                                       C\:\\Windows\\System32\\msiexec.exe or
127                                       C\:\\Windows\\System32\\CloudExperienceHostBroker.exe or
128                                       C\:\\Windows\\System32\\RuntimeBroker.exe or
129                                       C\:\\Windows\\System32\\wbem\\WmiPrvSE.exe or
130                                       C\:\\Windows\\System32\\SrTasks.exe or
131                                       C\:\\Windows\\System32\\diskshadow.exe or
132                                       C\:\\Windows\\System32\\dfsrs.exe or
133                                       C\:\\Windows\\System32\\vssadmin.exe or
134                                       C\:\\Windows\\System32\\dllhost.exe or
135                                       C\:\\Windows\\System32\\mmc.exe or
136                                       C\:\\Windows\\System32\\SettingSyncHost.exe or
137                                       C\:\\Windows\\System32\\inetsrv\\w3wp.exe or
138                                       C\:\\Windows\\System32\\wsmprovhost.exe or
139                                       C\:\\Windows\\System32\\mstsc.exe or
140                                       C\:\\Windows\\System32\\esentutl.exe or
141                                       C\:\\Windows\\System32\\RecoveryDrive.exe or
142                                       C\:\\Windows\\System32\\SystemPropertiesComputerName.exe or
143                                       C\:\\Windows\\SysWOW64\\msiexec.exe or
144                                       C\:\\Windows\\System32\\taskhostw.exe or
145                                       C\:\\Windows\\ImmersiveControlPanel\\SystemSettings.exe or
146                                       C\:\\Windows\\Temp\\rubrik_vmware*\\snaptool.exe or
147                                       C\:\\Windows\\VeeamVssSupport\\VeeamGuestHelper.exe or
148                                       C\:\\WindowsAzure\\*WaAppAgent.exe or
149                                       C\:\\$WINDOWS.~BT\\Sources\\*.exe
150                                      )
151  )
152'''
153
154
155[[rule.filters]]
156
157[rule.filters.meta]
158negate = true
159[rule.filters.query.wildcard."winlog.event_data.CallerProcessName"]
160case_insensitive = true
161value = "C:\\\\Program Files (x86)\\\\*.exe"
162[[rule.filters]]
163
164[rule.filters.meta]
165negate = true
166[rule.filters.query.wildcard."winlog.event_data.CallerProcessName"]
167case_insensitive = true
168value = "C:\\\\Program Files\\\\*.exe"
169[[rule.threat]]
170framework = "MITRE ATT&CK"
171[[rule.threat.technique]]
172id = "T1069"
173name = "Permission Groups Discovery"
174reference = "https://attack.mitre.org/techniques/T1069/"
175[[rule.threat.technique.subtechnique]]
176id = "T1069.001"
177name = "Local Groups"
178reference = "https://attack.mitre.org/techniques/T1069/001/"
179
180
181
182[rule.threat.tactic]
183id = "TA0007"
184name = "Discovery"
185reference = "https://attack.mitre.org/tactics/TA0007/"
186
187[rule.new_terms]
188field = "new_terms_fields"
189value = ["winlog.event_data.CallerProcessName"]
190[[rule.new_terms.history_window_start]]
191field = "history_window_start"
192value = "now-5d"