Microsoft 365 Token-Replay Attacks Compromise 97 Accounts at 79 Organizations: The Hacker News Research

Executive Summary

According to security intelligence published by The Hacker News, Cybersecurity researchers have disclosed a Microsoft 365 campaign that has been observed leveraging an adversary-in-the-middle (AitM) relay to capture sign-in sessions and then replay the stolen tokens to break into email accounts at 79 organizations.

Huntress, which observed the activity between July 14 and September 22, 2026, said it detected 497 successful Microsoft 365 sign-in events across the victim organizations from over 200,000 login attempts, with the attackers ultimately compromising 97 accounts and registering 48 rogue Entra devices.

"Rather than guessing passwords, the attacker replayed sign-in tokens stolen from victims, and we've traced more than 200,000 failed login attempts from the campaign window back to the 193.26.115[.]0/24 IP range," Huntress researchers Andrea Hatcher, Susannah Matt, Matt Poto, and Andrew Schwartz said.

Technical Context

Security advisories and threat research published by The Hacker News highlight the importance of auditing distributed microservices, validating automated integrations, and eliminating unintended public service exposures.

Key Considerations for Infrastructure Teams

• Service Discovery & Exposure Audits: Continuously scan internet-facing assets and microservices to detect unintended public exposure.
• Authentication & Protocol Hardening: Enforce strict mutual TLS (mTLS) or robust token-based authentication on all management interfaces.
• Vulnerability Lifecycle Management: Maintain automated dependency tracking and rapid patching protocols for third-party protocols and libraries.

Recommended Mitigation Steps

1. Review internal systems and endpoints matching the advisory scope disclosed by The Hacker News.
2. Restrict external network access and implement least-privilege network controls for background services.
3. Conduct deep endpoint audits using automated testing tooling to verify secure handshake and header configurations.

Editorial Notice: This bulletin is an independent editorial summary based on reporting and disclosures published by The Hacker News. CertificateGuardian curates industry intelligence to assist infrastructure teams in securing web endpoints.