Potential Kerberos Coercion by Spoofing SPNs via DNS Manipulation

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.

title: Potential Kerberos Coercion by Spoofing SPNs via DNS Manipulation
id: b07e58cf-cacc-4135-8473-ccb2eba63dd2
related:
    - id: e7a21b5f-d8c4-4ae5-b8d9-93c5d3f28e1c # Suspicious DNS Query Indicating Kerberos Coercion via DNS Object Spoofing
      type: similar
    - id: 5588576c-5898-4fac-bcdd-7475a60e8f43 # Suspicious DNS Query Indicating Kerberos Coercion via DNS Object Spoofing - Network
      type: similar
    - id: 0ed99dda-6a35-11ef-8c99-0242ac120002 # Kerberos Coercion Via DNS SPN Spoofing Attempt
      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: # ObjectDN">DC=foo-11UWhRCAAAAAAAAAAAAAAAAAAAAAAAAAAAAwbEAYBAAAA,DC=domain.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=domain,DC=com</Data>
            - 'UWhRCA'
            - 'BAAAA'
            - 'CN=MicrosoftDNS'
    selection_directory_service_access:
        EventID: 4662
        AdditionalInfo|contains|all: # AdditionalInfo">DC=foo-11UWhRCAAAAAAAAAAAAAAAAAAAAAAAAAAAAwbEAYBAAAA,DC=domain.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=domain,DC=com</Data>
            - 'UWhRCA'
            - 'BAAAA'
            - 'CN=MicrosoftDNS'
    condition: 1 of selection_*
falsepositives:
    - Unknown
level: high

• T1557.003DHCP Spoofing

• 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↗