Name:Azure AD User ImmutableId Attribute Updated id:0c0badad-4536-4a84-a561-5ff760f3c00e version:4 date:2024-09-30 author:Mauricio Velazco, Gowthamaraj Rajendran, Splunk status:production type:TTP Description:The following analytic identifies the modification of the SourceAnchor (ImmutableId) attribute for an Azure Active Directory user. This detection leverages Azure AD audit logs, specifically monitoring the "Update user" operation and changes to the SourceAnchor attribute. This activity is significant as it is a step in setting up an Azure AD identity federation backdoor, allowing an adversary to establish persistence. If confirmed malicious, the attacker could impersonate any user, bypassing password and MFA requirements, leading to unauthorized access and potential data breaches. Data_source:
-Azure Active Directory Update user
search:`azure_monitor_aad` operationName="Update user" properties.targetResources{}.modifiedProperties{}.displayName=SourceAnchor | rename properties.* as * | rename initiatedBy.user.userPrincipalName as initiatedBy | rename targetResources{}.modifiedProperties{}.newValue as modifiedProperties | stats count min(_time) as firstTime max(_time) as lastTime values(user) as user values(modifiedProperties) as modifiedProperties by initiatedBy, src_ip, result, operationName | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `azure_ad_user_immutableid_attribute_updated_filter`
how_to_implement:You must install the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase(https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Active Directory events into your Splunk environment. This analytic was written to be used with the azure:monitor:aad sourcetype leveraging the AuditLog log category. known_false_positives:The SourceAnchor (also called ImmutableId) Azure AD attribute has legitimate uses for directory synchronization. Investigate and filter as needed. References: -https://docs.microsoft.com/en-us/azure/active-directory/hybrid/plan-connect-design-concepts -https://www.mandiant.com/resources/remediation-and-hardening-strategies-microsoft-365-defend-against-apt29-v13 -https://o365blog.com/post/federation-vulnerability/ -https://www.inversecos.com/2021/11/how-to-detect-azure-active-directory.html -https://www.mandiant.com/resources/blog/detecting-microsoft-365-azure-active-directory-backdoors -https://attack.mitre.org/techniques/T1098/ drilldown_searches: name:'View the detection results for - "$user$"' search:'%original_detection_search% | search user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Azure Active Directory Persistence' asset_type:Azure Active Directory confidence:90 impact:50 message:The SourceAnchor or ImmutableID attribute has been modified for user $user$ by $initiatedBy$ mitre_attack_id: - 'T1098' observable: name:'user' type:'User' - role: - 'Victim' name:'initiatedBy' type:'User' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' risk_score:45 security_domain:threat
