Direct answer
Correlate failed sign-ins with the account, target device, logon type, source and timing, then investigate patterns alongside approved activity and account lockout events.
Read the event context
Microsoft documents event 4625 on the computer where a logon attempt failed. Record the time, account, target, logon type and available source details in an access-controlled system. Individual fields can be missing or vary with the authentication path.
Reference: Microsoft: Security event 4625.
Distinguish causes
A single failure may be a mistyped password; repeated attempts from a service after a credential change may indicate stale configuration. Correlate volume, source, timing and related successful logons or lockouts. Do not try passwords against the account to reproduce a suspected attack.
Escalate and resolve
The incident team should investigate unexplained or distributed patterns under its playbook. For a confirmed service misconfiguration, coordinate credential updates with the application owner and verify the failures stop. Preserve relevant evidence and monitor recurrence.
Investigate a stale scheduled credential
Repeated failures from the same server shortly after a password rotation can result from a scheduled job using old credentials. Match the account, logon type, source and schedule with the job owner, then update the secret through the approved process. Continue monitoring for failures from other sources that the job does not explain.
Assessment limits
The event reflects the observed failure and available fields; missing events do not establish that no attempts occurred. Collection, audit policy and retention affect visibility.
Frequently asked questions
Is every 4625 event an attack?
No. Normal mistakes and stale service credentials can also cause failures; investigate patterns and context.
Where is the event recorded?
Microsoft says the event is generated on the computer where the logon attempt was made.
Can source fields always identify the origin?
No. Available fields depend on the logon path and must be corroborated.
Primary sources and further reading
These guides combine published security guidance with practical assessment planning. Adapt checks to the owner's policy, environment, and authorized scope.
This guide was prepared with AI assistance using the linked sources and illustrative examples. Check current vendor guidance and your environment before making changes.