MediumSplunk security content Mauricio Velazco +1

Windows Multiple Users Failed To Authenticate From Host Using NTLM

Description

The following analytic identifies a single source endpoint failing to authenticate with 30 unique valid users using the NTLM protocol. It leverages EventCode 4776 from Domain Controller logs, focusing on error code 0xC000006A, which indicates a bad password. This behavior is significant as it may indicate a Password Spraying attack, where an adversary attempts to gain initial access or elevate privileges. If confirmed malicious, this activity could lead to unauthorized access to sensitive information or further compromise of the Active Directory environment.

Detection logic

Detection requirements

Platform: Containers ESXi IaaS Identity Provider Linux macOS Network Devices Office Suite SaaS Windows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
Log source category: windows_event_log_security_4776

Known benign triggers

A host failing to authenticate with multiple valid domain users is not a common behavior for legitimate systems. Possible false positive scenarios include but are not limited to vulnerability scanners and missconfigured systems. If this detection triggers on a host other than a Domain Controller, the behavior could represent a password spraying attack against the host's local accounts.

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
attack.mitre.org/techniques/T1110/003/	Taxonomy	40
docs.microsoft.com/en-us/windows/security/threat-protection/auditing/audit-credential-validation	Product documentation	4
docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4776	Product documentation	4
github.com/redcanaryco/atomic-red-team/blob/388942adbd9641f4dfdcf079d7efe9a75ec0ac43/atomics/T1110.003/T1110.003.yaml#L55	Detection test	Only this detection cites it

Detection rules

Windows Multiple Users Failed To Authenticate From Host Using NTLM

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules