Name:Windows AD Replication Request Initiated by User Account id:51307514-1236-49f6-8686-d46d93cc2821 version:5 date:2024-11-28 author:Dean Luxton status:production type:TTP Description:The following analytic detects a user account initiating an Active Directory replication request, indicative of a DCSync attack. It leverages EventCode 4662 from the Windows Security Event Log, focusing on specific object types and replication permissions. This activity is significant because it can allow an attacker with sufficient privileges to request password hashes for any or all users within the domain. If confirmed malicious, this could lead to unauthorized access, privilege escalation, and potential compromise of the entire domain. Data_source:
-Windows Event Log Security 4662
search:`wineventlog_security` EventCode=4662 ObjectType IN ("%{19195a5b-6da0-11d0-afd3-00c04fd930c9}", "domainDNS") AND Properties IN ("*Replicating Directory Changes All*", "*{1131f6ad-9c07-11d1-f79f-00c04fc2dcd2}*", "*{9923a32a-3607-11d2-b9be-0000f87a36b2}*","*{1131f6ac-9c07-11d1-f79f-00c04fc2dcd2}*") AND AccessMask="0x100" AND NOT (SubjectUserSid="NT AUT*" OR SubjectUserSid="S-1-5-18" OR SubjectDomainName="Window Manager" OR SubjectUserName="*$") | stats min(_time) as _time, count by SubjectDomainName, SubjectUserName, Computer, Logon_ID, ObjectName, ObjectServer, ObjectType, OperationType, status | rename SubjectDomainName as Target_Domain, SubjectUserName as user, Logon_ID as TargetLogonId, _time as attack_time | appendpipe [| map search="search `wineventlog_security` EventCode=4624 TargetLogonId=$TargetLogonId$"] | table attack_time, AuthenticationPackageName, LogonProcessName, LogonType, TargetUserSid, Target_Domain, user, Computer, TargetLogonId, status, src_ip, src_category, ObjectName, ObjectServer, ObjectType, OperationType | stats min(attack_time) as _time values(TargetUserSid) as TargetUserSid, values(Target_Domain) as Target_Domain, values(user) as user, values(Computer) as Computer, values(status) as status, values(src_category) as src_category, values(src_ip) as src_ip by TargetLogonId | `windows_ad_replication_request_initiated_by_user_account_filter`
how_to_implement:To successfully implement this search, you need to be ingesting eventcode `4662`. The Advanced Security Audit policy settings `Audit Directory Services Access` within `DS Access` needs to be enabled, as well as the following SACLs applied to the domain root and all descendant objects. The principals `everybody`, `Domain Computers`, and `Domain Controllers` auditing the permissions `Replicating Directory Changes`, `Replicating Directory Changes All`, and `Replicating Directory Changes In Filtered Set` known_false_positives:Azure AD Connect syncing operations. References: -https://adsecurity.org/?p=1729 -https://www.linkedin.com/pulse/mimikatz-dcsync-event-log-detections-john-dwyer -https://github.com/SigmaHQ/sigma/blob/0.22-699-g29a5c6278/rules/windows/builtin/security/win_security_dcsync.yml drilldown_searches: name:'View the detection results for - "$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: - 'Compromised Windows Host' - 'Sneaky Active Directory Persistence Tricks' - 'Credential Dumping' asset_type:Endpoint confidence:100 impact:100 message:Windows Active Directory Replication Request Initiated by User Account $user$ at $src_ip$ mitre_attack_id: - 'T1003.006' - 'T1003' observable: name:'user' type:'User' - role: - 'Victim' name:'src_ip' type:'IP Address' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'EventCode' - 'ObjectType' - 'Properties' - 'AccessMask' - 'SubjectDomainName' - 'SubjectUserName' - 'SubjectUserSid' - 'Computer' - 'Logon_ID' - 'ObjectName' - 'ObjectServer' - 'ObjectType' - 'OperationType' - 'status' risk_score:100 security_domain:endpoint
