Query: Sigma rule for Detects modifications to DNS records in Active Directory where the Distinguished Name (DN) contains a base64-encoded blo
Matching passage: Sigma rule: Detects modifications to DNS records in Active Directory where the Distinguished Name (DN) contains a base64-encoded blo. Logsource: windows / security. Rule: title: Potential Kerberos Coercion by Spoofing SPNs via DNS Manipulation id: b07e58cf-cacc-4135-8473-ccb2eba63dd2 related: - id: e7a21b5f-d8c4-4ae5-b8d9-93c5d3f28e1c type: similar - id: 5588576c-5898-4fac-bcdd-7475a60e8f43 type: similar - id: 0ed99dda-6a35-11ef-8c99-0242ac120002 type: similar status: experimental description: 'Detects modifications to DNS records in Active Directory where the Distinguished Name (DN) contains a base64-encoded blob matching the pattern "1UWhRCAAAAA...BAAAA". This pattern corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure, commonly used in Kerberos coercion attacks. Adversaries may exploit this to coerce victim systems into authenticating to attacker-controlled hosts by spoofing SPNs via DNS. It is one of the strong indicators of a Kerberos coercion attack,. where adversaries manipulate DNS records to spoof Service Principal Names (SPNs) and redirect authentication requests like CVE-2025-33073. Please investigate the user account that made the changes, as it is likely a low-privileged account that has been compromised. ' references: - https://googleprojectzero.blogspot.com/2021/10/using-kerberos-for-authentication-relay.html - https://www.synacktiv.com/publications/ntlm-reflection-is-dead-long-live-ntlm-reflection-an-in-depth-analysis-of-cve-2025 author: Swachchhanda Shrawan Poudel (Nextron Systems) date: 2025-06-20 tags: - attack.collection - attack.credential-access - attack.t1557.003 - attack.persistence - attack.privilege-escalation logsource: product: windows service: security definition: 'By default these events are not logged by default for MicrosoftDNS objects in Active Directory. To enable detection, configure an AuditRule on the DNS object container with the "CreateChild" permission for the "Everyone" principal. This can be accomplished using tools such as Set-AuditRule (see https://github.com/OTRF/Set-AuditRule). ' detection: selection_directory_service_changes: EventID: - 5136 - 5137 ObjectClass: dnsNode ObjectDN|contains|all: - UWhRCA - BAAAA - CN=MicrosoftDNS selection_directory_service_access: EventID: 4662 AdditionalInfo|contains|all: - UWhRCA - BAAAA - CN=MicrosoftDNS condition: 1 of selection_* falsepositives: - Unknown level: high
Near-miss passage: Sigma rule: Detects calls to cmdlets that are used to export certificates from the local certificate store. Threat actors were seen. Logsource: windows / process_creation. Rule: title: Certificate Exported Via PowerShell id: 9e716b33-63b2-46da-86a4-bd3c3b9b5dfb related: - id: aa7a3fce-bef5-4311-9cc1-5f04bb8c308c type: similar status: test description: Detects calls to cmdlets that are used to export certificates from the local certificate store. Threat actors were seen abusing this to steal private keys from compromised machines. references: - https://us-cert.cisa.gov/ncas/analysis-reports/ar21-112a - https://learn.microsoft.com/en-us/powershell/module/pki/export-pfxcertificate?view=windowsserver2022-ps - https://www.splunk.com/en_us/blog/security/breaking-the-chain-defending-against-certificate-services-abuse.html author: Nasreddine Bencherchali (Nextron Systems) date: 2023-05-18 tags: - attack.credential-access - attack.execution - attack.t1552.004 - attack.t1059.001 logsource: product: windows category: process_creation detection: selection: CommandLine|contains: - 'Export-PfxCertificate ' - 'Export-Certificate ' condition: selection falsepositives: - Legitimate certificate exports by administrators. Additional filters might be required. level: medium