Threat Actors Target Microsoft 365 Accounts In OAuth Token Theft Operation

Threat Actors Target Microsoft 365 Accounts In OAuth Token Theft Operation

Why This Matters Now: In December 2023, threat actors launched a sophisticated OAuth token theft operation targeting Microsoft 365 accounts. This breach exposed thousands of tokens, putting sensitive data at risk. If you’re using OAuth for Microsoft 365 integrations, understanding and addressing this threat is crucial. 🚨 Breaking: Over 5,000 OAuth tokens stolen in recent Microsoft 365 breach. Validate your client configurations and rotate secrets immediately. 5,000+Tokens Stolen 24hrsTime to Act Understanding the Attack Vector Threat actors exploited a misconfigured OAuth client application within a Microsoft 365 environment. The attackers used a combination of social engineering and configuration weaknesses to obtain unauthorized access to OAuth tokens. These tokens grant access to various resources within the Microsoft 365 ecosystem, including email, calendar, and file storage. ...

Feb 23, 2026 · 4 min · 785 words · IAMDevBox