AI-Powered Phishing Attack Targets Microsoft 365 Accounts, Experts Warn

Cybersecurity researchers uncovered a sophisticated phishing campaign that exploited a legitimate artificial intelligence platform to steal corporate Microsoft 365 credentials. The attack, detailed by Cato Networks and reported by Cyber Security News, demonstrated how cybercriminals increasingly leverage the trust placed in AI tools to bypass traditional defenses. At least one U.S.-based investment company was affected before the campaign was shut down, highlighting the growing risks of AI-enabled attacks.

The operation began with carefully crafted phishing emails impersonating executives from a global pharmaceutical distributor. To enhance credibility, attackers used real logos and verified LinkedIn profiles, making the communications appear authentic. These emails contained password-protected PDF attachments, a tactic that allowed them to evade automated security scanners. The password, conveniently included in the message body, gave the appearance of a routine corporate practice.

Once opened, the documents redirected recipients to Simplified AI, a legitimate marketing platform widely recognized and trusted in corporate environments. The attackers cleverly manipulated the platform to display the pharmaceutical company’s branding alongside Microsoft 365 design elements. This combination reinforced the illusion of legitimacy and lowered suspicion among users.

The final stage involved redirecting victims to a fraudulent Microsoft 365 login portal that closely replicated the official page. Any credentials entered there were harvested by attackers, granting them unauthorized access to sensitive corporate accounts. According to Cato Networks, the use of a legitimate AI service provided attackers with cover, allowing them to hide malicious activity within normal enterprise traffic.

Security experts stress that this incident reflects a broader trend. Cybercriminals no longer need to rely on suspicious domains or poorly maintained servers; instead, they exploit the reputation of trusted platforms, making detection significantly more difficult. The campaign illustrates how “shadow AI” adoption—when employees use unsanctioned tools without oversight—creates additional vulnerabilities for organizations.

To mitigate risks, experts recommend adopting a layered defense strategy. Key measures include enabling multifactor authentication for all critical services, training employees to treat password-protected attachments with caution, and monitoring the use of AI platforms, including unauthorized applications. Continuous inspection of AI-related traffic and deployment of advanced threat detection solutions capable of identifying unusual behavior patterns are also strongly advised.

Filed in Cellphones >Computers >Tablets >Web. Read more about AI (Artificial Intelligence), Microsoft and Phishing.