Suspicious DNS Query Indicating Kerberos Coercion via DNS Object SPN Spoofing
Detects DNS queries containing patterns associated with Kerberos coercion attacks via DNS object spoofing. The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure. Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts. 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.
Sigma rule (View on GitHub)
1title: Suspicious DNS Query Indicating Kerberos Coercion via DNS Object SPN Spoofing
2id: e7a21b5f-d8c4-4ae5-b8d9-93c5d3f28e1c
3related:
4 - id: b07e58cf-cacc-4135-8473-ccb2eba63dd2 # Potential Kerberos Coercion via DNS Object Spoofing
5 type: similar
6 - id: 5588576c-5898-4fac-bcdd-7475a60e8f43 # Suspicious DNS Query Indicating Kerberos Coercion via DNS Object Spoofing - Network
7 type: similar
8status: experimental
9description: |
10 Detects DNS queries containing patterns associated with Kerberos coercion attacks via DNS object spoofing.
11 The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure.
12 Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts.
13 It is one of the strong indicators of a Kerberos coercion attack, where adversaries manipulate DNS records
14 to spoof Service Principal Names (SPNs) and redirect authentication requests like CVE-2025-33073.
15references:
16 - https://www.synacktiv.com/publications/ntlm-reflection-is-dead-long-live-ntlm-reflection-an-in-depth-analysis-of-cve-2025
17 - https://googleprojectzero.blogspot.com/2021/10/using-kerberos-for-authentication-relay.html
18author: Swachchhanda Shrawan Poudel (Nextron Systems)
19date: 2025-06-20
20tags:
21 - attack.credential-access
22 - attack.persistence
23 - attack.privilege-escalation
24 - attack.t1557.001
25 - attack.t1187
26logsource:
27 product: windows
28 category: dns_query
29detection:
30 selection:
31 QueryName|contains|all:
32 - 'UWhRCA'
33 - 'BAAAA'
34 condition: selection
35falsepositives:
36 - Unknown
37level: high
References
Related rules
- Attempts of Kerberos Coercion Via DNS SPN Spoofing
- Suspicious DNS Query Indicating Kerberos Coercion via DNS Object SPN Spoofing - Network
- Potential Kerberos Coercion by Spoofing SPNs via DNS Manipulation
- Potential PetitPotam Attack Via EFS RPC Calls
- Application AppID Uri Configuration Changes