How to Investigate a Sudden Increase in Failed Business Account Sign-Ins

A spike in failed sign-ins can reflect a password spray, a misconfigured application, an expired credential, or a normal user change such as a device rollout. Blocking all affected accounts without context may interrupt operations while missing the actual source.

What to check

Group events by source, target accounts, application, location, and time. Check user-agent patterns, legacy authentication, recent deployments, known service accounts, and successful sign-ins near the failures. Preserve logs and verify the detection window.

Recommended next step

Contain confirmed malicious sources and protect targeted accounts according to policy. Fix legitimate stale credentials or application configuration, then monitor whether failures stop and whether any suspicious sign-in succeeded.

How Informatix Systems can help

Informatix Systems provides security operations and incident response services. We can review the affected systems and workflow, help identify likely causes, and outline a practical implementation path. Contact us with the platform involved, when the issue began, and non-sensitive error details.