Cybersecurity researchers have disclosed details of a new adversary-in-the-middle (AitM) phishing toolkit called NovaCookies that's used as a proxy to redirect Microsoft 365 sign-ins, while capturing authenticated sessions in the process.

In a report shared with The Hacker News ahead of publication, Island characterized the $320/month service as a subscription-based phishing platform that facilitates real-time Microsoft 365 session theft. The kit has been used to target hundreds of organizations across multiple sectors in the U.S., the U.K., Canada, Germany, Israel, and the U.A.E. to date.

"Observed campaigns used genuine Docusign envelopes to carry counterfeit document-share lures, with some clicks routed through legitimate Microsoft or Google sign-in endpoints as redirect hops before reaching the kit," Island said. "The message, document service and redirect can therefore appear trustworthy until the browser reaches attacker-controlled infrastructure."

Like other AitM phishing kits, NovaCookies is designed to relay Microsoft 365 authentication through attacker-controlled infrastructure, allowing it to act as a proxy and harvest the resulting session after victims enter their passwords and multi-factor authentication (MFA) codes.