1200KM / sigma-rule
Attempts of Kerberos Coercion Via DNS SPN Spoofing — Sigma Rule
Sigma rule 0ed99dda-6a35-11ef-8c99-0242ac120002. Attempts of Kerberos Coercion Via DNS SPN Spoofing — Sigma Rule. Detects the presence of "UWhRC....AAYBAAAA" pattern in command line. 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 in CVE-2025-33073. If you see this pattern in the command line, it is likely an attempt to add spoofed Service Principal Names (SPNs) to DNS records, or checking for the presence of such records through the `nslookup` command.
Rule metadata and linked tags
Author: Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: high. Source dates: 2025-06-20 / not supplied.
{
"category": "process_creation",
"product": "windows"
}Pinned original Sigma rule · Detection Rule License 1.1
Source SHA-256: 224582f857a4b1d4df8e496629c409378837037c98fb9d9e34c4a2771e419cf4
Detection logic
Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.
title: Attempts of Kerberos Coercion Via DNS SPN Spoofing
id: 0ed99dda-6a35-11ef-8c99-0242ac120002
related:
- id: b07e58cf-cacc-4135-8473-ccb2eba63dd2
type: similar
status: experimental
description: |
Detects the presence of "UWhRC....AAYBAAAA" pattern in command line.
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 in CVE-2025-33073.
If you see this pattern in the command line, it is likely an attempt to add spoofed Service Principal Names (SPNs) to DNS records,
or checking for the presence of such records through the `nslookup` command.
references:
- https://www.synacktiv.com/publications/ntlm-reflection-is-dead-long-live-ntlm-reflection-an-in-depth-analysis-of-cve-2025
- https://googleprojectzero.blogspot.com/2021/10/using-kerberos-for-authentication-relay.html
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-06-20
tags:
- attack.collection
- attack.credential-access
- attack.persistence
- attack.privilege-escalation
- attack.t1557.001
- attack.t1187
logsource:
category: process_creation
product: windows
detection:
selection:
CommandLine|contains|all:
- 'UWhRCA'
- 'BAAAA'
condition: selection
falsepositives:
- Unknown
level: high
False positives
- Unknown
Source references
Connected ecosystem references
Exact source-tagged techniques
Telemetry review
Read the original logsource above, then inspect the linked detection workspaces for technique-level sensor context. No per-rule telemetry equivalence is inferred.
Pinned research references. No browser attack runner, live simulation result or validated detector is asserted. Source mappings and validation limits are preserved. ATT&CK / Atomic provenance · Detection provenance.