Query: detect Detects suspicious Active Directory Replication Service (ADRS) requests originating from a machine account (SubjectUserN in logs
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 the execution of "sysctl" with specific arguments that have been used by threat actors and malware. It provides. Logsource: macos / process_creation. Rule: title: System Information Discovery Via Sysctl - MacOS id: 6ff08e55-ea53-4f27-94a1-eff92e6d9d5c status: test description: 'Detects the execution of "sysctl" with specific arguments that have been used by threat actors and malware. It provides system hardware information. This process is primarily used to detect and avoid virtualization and analysis environments. ' references: - https://www.loobins.io/binaries/sysctl/# - https://evasions.checkpoint.com/techniques/macos.html - https://www.welivesecurity.com/2019/04/09/oceanlotus-macos-malware-update/ - https://www.sentinelone.com/labs/20-common-tools-techniques-used-by-macos-threat-actors-malware/ - https://objective-see.org/blog/blog_0x1E.html - https://www.virustotal.com/gui/file/1c547a064494a35d6b5e6b459de183ab2720a22725e082bed6f6629211f7abc1/behavior - https://www.virustotal.com/gui/file/b4b1fc65f87b3dcfa35e2dbe8e0a34ad9d8a400bec332025c0a2e200671038aa/behavior author: Pratinav Chandra date: 2024-05-27 tags: - attack.stealth - attack.t1497.001 - attack.discovery - attack.t1082 logsource: product: macos category: process_creation detection: selection_img: - Image|endswith: /sysctl - CommandLine|contains: sysctl selection_cmd: CommandLine|contains: - hw. - kern. - machdep. condition: all of selection_* falsepositives: - Legitimate administrative activities level: medium