Microsoft 365 Mailbox Rules Are Being Weaponized
Microsoft 365 mailbox rules are being weaponized as a core technique behind $2.77 billion in annual Business Email Compromise losses, and attackers are creating hidden rules that survive password resets, MFA enrollment, and session invalidation. A new Proofpoint report reveals that 10% of all compromised Microsoft 365 accounts get malicious inbox rules installed within seconds of the initial breach, targeting 400+ million users worldwide by abusing built-in email functionality no security tool will ever flag as suspicious. 😏









