O365 Multiple AppIDs and UserAgents Authentication Spike
The following analytic identifies unusual authentication activity in an O365 environment, where a single user account experiences more than 8 authentication attempts using 3 or more unique application IDs and over 5…
Description
The following analytic identifies unusual authentication activity in an O365 environment, where a single user account experiences more than 8 authentication attempts using 3 or more unique application IDs and over 5 unique user agents within a short timeframe. It leverages O365 audit logs, focusing on authentication events and applying statistical thresholds. This behavior is significant as it may indicate an adversary probing for multi-factor authentication weaknesses. If confirmed malicious, it suggests a compromised account, potentially leading to unauthorized access, privilege escalation, and data exfiltration. Early detection is crucial to prevent further exploitation.
Detection logic
Detection requirements
- Platform
- ContainersESXiIaaSIdentity ProviderLinuxmacOSNetwork DevicesOffice SuiteSaaSWindows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- o365_userloggedino365_userloginfailed
Known benign triggers
- Rapid authentication from the same user using more than 5 different user agents and 3 application IDs is highly unlikely under normal circumstances. However, there are potential scenarios that could lead to false positives.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| attack.mitre.org/techniques/T1078/ | 8from 2 sources |
| github.com/dafthack/MFASweep | 2 |
| www.blackhillsinfosec.com/exploiting-mfa-inconsistencies-on-microsoft-services/ | 3 |
| www.youtube.com/watch?v=SK1zgqaAZ2E | 2 |
From the source
- At source
- Open at source
- Upstream identifier
- 66adc486-224d-45c1-8e4d-9e7eeaba988f
- Tagged by the source as
- Office 365 Account TakeoverO365 TenantcloudSplunk CloudSplunk EnterpriseSplunk Enterprise Securityidentity
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1