Suspicious DNS Query Indicating Kerberos Coercion via DNS Object SPN Spoofing

Severity: high
Author: Swachchhanda Shrawan Poudel (Nextron Systems)
Source: upstream

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.

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1187` Forced Authentication, `T1557.001` Adversary-in-the-Middle: LLMNR/NBT-NS Poisoning and SMB Relay
Collection	`T1557.001` Adversary-in-the-Middle: LLMNR/NBT-NS Poisoning and SMB Relay

Event coverage

Provider	Event ID	Title
Sysmon	22	DNSEvent (DNS query)

Stages and Predicates

Stage 1: `selection`

QueryName|contains: BAAAA
QueryName|contains: UWhRCA

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.