Potential MFA Bypass Using Legacy Client Authentication

Detects successful authentication from potential clients using legacy authentication via user agent strings. This could be a sign of MFA bypass using a password spray attack.

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 2 ATT&CK techniques it maps to.
Log source product: azure
Log source service: signinlogs

Known benign triggers

Known Legacy 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
web.archive.org/web/20230217071802/https://blooteem.com/march-2022	Unclassified	Only this detection cites it
www.microsoft.com/en-us/security/blog/2021/10/26/protect-your-business-from-password-sprays-with-microsoft-dart-recommendations/	Threat report	Only this detection cites it

Detection rules

Potential MFA Bypass Using Legacy Client Authentication

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules