Adversary-in-the-Middle Phishing and Evasion Techniques That Bypass MFA
Adversary-in-the-middle (AiTM) phishing continues to undermine traditional MFA by proxying legitimate Microsoft sign-in flows in real time, allowing attackers to capture not only passwords but also session tokens and MFA responses. One investigation described how sophisticated redirect infrastructure (e.g., unusually deep redirect chains) can place the final phishing content beyond the reach of many email security scanners, and how one-time URL tokens can prevent defenders from reproducing the full chain after the fact—making in-the-moment evidence collection critical. The same analysis emphasized that phishing-resistant MFA (e.g., FIDO2/passkeys) is a more effective control because hardware-bound credentials cannot be relayed through a proxy.
Operationally, defenders are being pushed to treat modern phishing as an infrastructure and workflow problem, not just a user-awareness issue: attackers increasingly use HTTPS, branded lookalike pages/domains, redirects, and short-lived links to evade detection, including QR phishing (codes embedded in PDFs that bypass URL scanning). Additional pressure tactics like MFA fatigue (push-spam) remain effective against push-based MFA, with mitigations including number matching, contextual prompts (e.g., location), and monitoring for abnormal push rates. For earlier detection of AiTM activity, one proposed tripwire is embedding Canary Tokens in Microsoft Entra ID tenant branding (e.g., custom CSS) to alert when an AiTM proxy loads the login page, while noting this is not universally reliable across all kits.
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How this story unfolded
5 events from the most recent confirmed update back to the earliest known activity.
Sekoia confirms previously undocumented PhaaS kit behind Hopper
After the investigator shared findings with Sekoia's TDR team, the team confirmed the activity was linked to a previously undocumented phishing-as-a-service kit. This marked a new attribution development for the Hopper campaign.
Researcher rules out several known AiTM and PhaaS kits
Technical analysis using mitmproxy and observed fingerprints led the author to systematically exclude Tycoon 2FA, Mamba 2FA, Sneaky 2FA, Gabagool, and Evilginx as matches for the campaign. This narrowed attribution toward a distinct, previously undocumented kit.
Investigation documents Hopper's seven-hop redirect architecture
During analysis of a single attack, the investigator identified a seven-hop redirect chain used for tracking, anti-bot checks, token generation, victim routing, and final proxy delivery. The findings showed how incomplete redirect resolution by email security tools can miss the final phishing destination.
Hopper phishing campaign operates across sectors for multiple months
Pivoting on the unique JavaScript filename "ui-form-security.js" via urlscan.io revealed a multi-month, multi-sector adversary-in-the-middle phishing campaign later dubbed Hopper. The operation proxied real Microsoft login flows to capture credentials, MFA responses, and session tokens.
Help Net Security video outlines modern phishing evasion techniques
Gal Livschitz of Terra Security described how current phishing attacks use HTTPS, branded spoof pages, lookalike domains, redirects, and short-lived links to evade detection, and highlighted QR phishing as a growing tactic. He also warned about MFA fatigue, AI-generated phishing, and voice cloning, while recommending phishing-resistant MFA and improved training and mobile controls.
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Adversary-in-the-Middle Phishing Attacks Targeting Microsoft 365
Threat actors are increasingly leveraging adversary-in-the-middle (AitM) phishing techniques to compromise Microsoft 365 accounts. In a recent incident, attackers used a phishing email with a malicious link that mimicked the Microsoft login page, capturing both credentials and session cookies to bypass multi-factor authentication (MFA). The attackers expanded their access through password spraying, brute force attacks, and the use of VPNs and residential proxies to evade detection. Persistence was achieved by manipulating inbox rules and abusing OAuth permissions via legitimate email clients, allowing continued access to compromised accounts. Traditional detection methods, such as URL reputation and static fingerprinting, are proving ineffective against these sophisticated AitM phishing kits, which proxy the real Microsoft authentication flow and associated assets. In response, security researchers have developed new defensive measures, including browser extensions that detect AitM attacks at the point of interaction by monitoring for unexpected HTTP referers and injecting visible warnings. However, as attackers adapt and proxy more elements of the authentication process, even these advanced defenses face challenges, highlighting the need for continuous innovation in anti-phishing strategies.
Jun 29, 2026
Multi-Stage Phishing Campaigns Bypassing MFA to Steal Microsoft 365 Credentials
A wave of sophisticated phishing campaigns is targeting organizations globally to steal Microsoft 365 credentials by bypassing traditional email security gateways and multi-factor authentication (MFA) protections. Attackers are employing advanced techniques such as multi-stage payload delivery using nested PDF attachments, legitimate content delivery networks, and mouse tracking to evade detection. Once victims interact with these emails and enter their credentials on a credential harvesting site, attackers leverage legitimate Microsoft infrastructure to bypass MFA and gain immediate access to the victim’s Microsoft 365 environment. These campaigns are engineered to filter out security analysts and block standard security tools, making detection and response more challenging. In parallel, threat actors are increasingly using attacker-in-the-middle toolkits like Evilginx and hybrid phishing-as-a-service kits such as Salty2FA and Tycoon2FA to capture both user credentials and session cookies. By stealing session cookies, attackers can impersonate users and maintain access without triggering additional MFA prompts, even after successful authentication. The blending of different phishing kits into hybrid strains is making detection harder, as traditional security rules tuned to individual kits are now being evaded. Security researchers warn that static indicators are no longer sufficient, and behavioral analysis is required to spot these evolving threats.
Jun 29, 2026
Credential-Based Attacks and the Shift Toward Phishing-Resistant MFA
Recent high-profile breaches at major UK retailers, including M&S and Co-op Group, have highlighted the growing threat of identity-based attacks. Attackers used vishing techniques to obtain corporate passwords, which enabled ransomware deployment and resulted in significant financial and reputational damage. The distributed nature of modern IT environments, with resources spread across cloud and on-premises systems, has made identity the new security perimeter, increasing the value of credentials for cybercriminals. Infostealer malware and various forms of phishing, including smishing and vishing, are now primary methods for harvesting credentials, contributing to a surge in identity-related breaches across industries. To counter these threats, security experts emphasize the importance of robust multifactor authentication (MFA), particularly methods that are resistant to phishing. While traditional MFA methods such as one-time passwords (OTPs) sent via SMS or email are still widely used, they are increasingly vulnerable to social engineering and interception. The adoption of passkeys and other phishing-resistant MFA solutions is being promoted as the gold standard, with Microsoft reporting that MFA blocks over 99% of unauthorized access attempts. Organizations are urged to move beyond basic MFA and implement stronger, phishing-resistant authentication to protect against evolving identity-based attacks.
Jun 29, 2026