Multiple users authenticated with weak NTLM to a host

Synopsis

Field	Value
Activation Period	14 Days
Training Period	30 Days
Test Period	1 Hour
Deduplication Period	1 Day
Required Data	XDR Agent
Detection Modules	Identity Analytics
ATT&CK Tactic	Lateral Movement (TA0008)
ATT&CK Technique	Use Alternate Authentication Material (T1550)
Severity	Informational

Description

Multiple user accounts authenticated to a host via NTLMv1 or LM authentication for the first time in the past 30 days. This may be a result of an NTLM downgrade attack A downgrade attack may force the client to authenticate with a weaker hash/protocol (such as NTLMv1 or even LM) instead of NTLMv2.

Attacker's Goals

The attacker attempts to gain access to the accounts.

Investigative actions

• Audit all login events with a weaker protocol and review any anomalous usage.
• Investigate the mentioned host for additional suspicious activity.