Varonis Threat Labs detailed a post-compromise technique it calls TrustSink, in which an attacker holding a highly privileged Microsoft Entra account registers a rogue External Authentication Method as an external MFA provider. During normal sign-ins, Entra redirects users to the rogue provider to complete the second factor, and the attacker inserts a convincing Microsoft password prompt that captures the password in plaintext before returning a valid signed token, so the login completes with no error. In testing, every sign-in succeeded while the attacker server logged passwords with source IPs. Resetting a captured password does not remove the rogue provider, which persists in the configuration and works against any external provider model.
Okta warns of a campaign that phones Microsoft 365 users and talks them through what looks like setting up a passkey, but is actually a phishing kit that hands their account to the attacker. Active since April, the operators register passkey-themed domains and call targets, exploiting unfamiliarity with how passkeys really work. The kit mimics Microsoft's passkey enrollment without registering a real passkey, and pushes the victim to "save a recovery key" that the attacker controls, capturing the access needed to take over the account. The campaign, aimed at extortion, notably targets the passkey adoption process itself, turning a security upgrade into a social-engineering opening.
TrustStrike Labs