Detection rule
NTLM logon from an unknown computer detection (T1078)
A domain controller got an NTLM network logon from an address no domain computer signs in from, with a workstation or domain the directory doesn't hold. Tools run from Linux hosts or containers look like this, and so do devices that aren't joined to the domain. GraphnAI raises an alert when it sees this in your domain controllers' security events.
How GraphnAI finds it
An OpenTelemetry collector sends the Windows Security log from your domain controllers to your GraphnAI server. GraphnAI checks each batch of events against every active rule.
This rule reads 2 events:
- 4624An account was successfully logged on
- 4625An account failed to log on
One matching event raises the alert.
The alert names the source. Triage assesses the most privileged account it targeted, and that account's paths to Tier 0.
Tiered Fidelity™ level: Validated
Telemetry saw the activity itself. The alert names a source address rather than an account, so it marks no identity in the graph.
- TheoreticalConfigured in the directory. Nothing else checked.
- ConstrainedA constraint on it has been checked.
- ValidatedThis alertTelemetry has seen it in use.
How you respond with Select Fire™
The alert is keyed by its source address, so it has no Select Fire button.
- Full-AutoTriage never acts on it automatically. An attacker chooses the accounts it names, so acting on one would let the attacker pick the account to lock out.
MITRE ATT&CK® technique names: © The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. ATT&CK® is a registered trademark of The MITRE Corporation.
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