Attempts of Kerberos Coercion Via DNS SPN Spoofing

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

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.

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	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `selection`

CommandLine|contains: BAAAA
CommandLine|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.