Microsoft is drawing attention to a growing threat in the cyber landscape — adversary-in-the-middle (AiTM) phishing techniques — particularly within the phishing-as-a-service (PhaaS) model. The tech giant highlights that not only are AiTM-capable PhaaS platforms on the rise, but established phishing services like PerSwaysion are also integrating AiTM capabilities.
Microsoft’s Threat Intelligence team underscores the significance of this evolution, as attackers employ AiTM strategies to conduct large-scale phishing campaigns with the aim of evading multi-factor authentication (MFA) defenses. The team’s series of posts on X outlines how this development empowers cybercriminals to challenge MFA protections on a broader scale.
The AiTM-capable phishing kits operate through two distinct methods. The first involves reverse proxy servers, allowing the phishing page to redirect traffic between the client and legitimate websites while stealthily capturing user credentials, two-factor authentication codes, and session cookies. The second method employs synchronous relay servers, presenting the target with a replica of a sign-in page, akin to traditional phishing attacks.
Microsoft highlights the involvement of the actor group “Storm-1295,” behind the Greatness PhaaS platform, which offers synchronous relay services to other attackers.
Greatness, initially identified by Cisco Talos in May 2023, is a service enabling cybercriminals to target Microsoft 365 cloud users through convincing decoy and login pages. This evolving threat group has been operational since at least mid-2022.
The ultimate goal of AiTM attacks is to seize session cookies, granting threat actors access to privileged systems without the need for reauthentication. Microsoft emphasizes that these new challenges require incident response procedures to include the revocation of stolen session cookies, highlighting the unique nature of AiTM attacks compared to traditional phishing tactics.
