Today we are joined by Selena Larson, co-host of Only Malware in the Building and Staff Threat Researcher and Lead Intelligence Analysis and Strategy at Proofpoint, sharing their work on "Microsoft OAuth App Impersonation Campaign Leads to MFA Phishing." Proofpoint researchers have identified campaigns where threat actors use fake Microsoft OAuth apps to impersonate services like Adobe, DocuSign, and SharePoint, stealing credentials and bypassing MFA via attacker-in-the-middle phishing kits, mainly Tycoon.
These attacks redirect users to fake Microsoft login pages to capture credentials, 2FA tokens, and session cookies, targeting nearly 3,000 Microsoft 365 accounts across 900 environments in 2025. Microsoft’s upcoming security changes and strengthened email, cloud, and web defenses, along with user education, are recommended to reduce these risks.
The research can be found here:
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