Query: detection rule: Detects suspicious Active Directory Replication Service (ADRS) requests originating from a machine account (SubjectUserN
Matching passage: Sigma rule: Detects suspicious Active Directory Replication Service (ADRS) requests originating from a machine account (SubjectUserN. Logsource: windows / security. Rule: title: Suspicious Machine Account Replication - DcSync Indicator id: 611eab06-a145-4dfa-a295-3ccc5c20f59a related: - id: 17d619c1-e020-4347-957e-1d1207455c93 type: similar status: test description: 'Detects suspicious Active Directory Replication Service (ADRS) requests originating from a machine account (SubjectUserName ending in ''$'') rather than a legitimate Domain Controller. Under normal operation, only Domain Controllers initiate replication requests carrying the DS-Replication-Get-Changes-All right. If a threat actor obtains valid machine account credentials — for example by abusing certificate-based authentication (PKINIT) to impersonate a DC after exploiting a CA vulnerability such as CVE-2026-54121 (Certighost), where a temporary machine account is created to request a DC certificate and then used to perform DCSync — they can dump all domain credential material including the krbtgt hash. ' references: - https://twitter.com/gentilkiwi/status/1003236624925413376 - https://gist.github.com/gentilkiwi/dcc132457408cf11ad2061340dcb53c2 - https://blog.blacklanternsecurity.com/p/detecting-dcsync?s=r - https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/auditing/event-4662 - https://github.com/aniqfakhrul/CVE-2026-54121 author: Benjamin Delpy, Florian Roth (Nextron Systems), Scott Dermett, Sorina Ionescu date: 2018-06-03 modified: 2026-07-30 tags: - attack.credential-access - attack.s0002 - attack.t1003.006 - cve.2026-54121 logsource: product: windows service: security definition: 'Requirements: A SACL must be configured on the domain NC root object (e.g. DC=domain,DC=com) to generate Event 4662. Add via ADSI Edit: navigate to the domain NC root → Properties → Security → Advanced → Auditing → add an ACE for Everyone, Type: Success, Applies to: This object only, rights: DS-Replication-Get-Changes and DS-Replication-Get-Changes-All. The OS audit subcategory must also be enabled: auditpol /set /subcategory:"Directory Service Access" /success:enable ' detection: selection: EventID: 4662 Properties|contains: - 1131f6ad-9c07-11d1-f79f-00c04fc2dcd2 - 1131f6aa-9c07-11d1-f79f-00c04fc2dcd2 - 9923a32a-3607-11d2-b9be-0000f87a36b2 - 89e95b76-444d-4c62-991a-0facbeda640c SubjectUserName|endswith: $ filter_main_subject_usersid: SubjectUserSid|startswith: S-1-5-18 condition: selection and not 1 of filter_main_* falsepositives: - Valid DC Sync that is not covered by the filters; please report level: medium
Near-miss passage: Sigma rule: Detects presence of a potentially xor encoded powershell command. Logsource: windows / process_creation. Rule: title: Suspicious XOR Encoded PowerShell Command id: bb780e0c-16cf-4383-8383-1e5471db6cf9 related: - id: 5b572dcf-254b-425c-a8c5-d9af6bea35a6 type: obsolete status: test description: Detects presence of a potentially xor encoded powershell command references: - https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=65 - https://redcanary.com/blog/yellow-cockatoo/ - https://zero2auto.com/2020/05/19/netwalker-re/ - https://mez0.cc/posts/cobaltstrike-powershell-exec/ author: Sami Ruohonen, Harish Segar, Tim Shelton, Teymur Kheirkhabarov, Vasiliy Burov, oscd.community, Nasreddine Bencherchali date: 2018-09-05 modified: 2023-01-30 tags: - attack.execution - attack.stealth - attack.t1059.001 - attack.t1140 - attack.t1027 logsource: category: process_creation product: windows detection: selection_img: - Image|endswith: - \powershell.exe - \pwsh.exe - OriginalFileName: - PowerShell.EXE - pwsh.dll - Description: Windows PowerShell - Product: PowerShell Core 6 selection_cli_xor: CommandLine|contains: bxor selection_cli_other: CommandLine|contains: - ForEach - for( - 'for ' - '-join ' - -join' - -join" - -join` - ::Join - '[char]' condition: all of selection_* falsepositives: - Unknown level: medium