Payroll Pirate Uses Microsoft Graph and AiTM Session Theft to Redirect Salaries
Attackers in the Payroll Pirate campaign are targeting HR, payroll, finance, and administrative staff by using adversary-in-the-middle phishing pages to steal active Microsoft 365 session tokens and take over accounts without needing passwords or defeating MFA directly. Researchers linked the activity to Microsoft-tracked clusters Storm-2755 and Storm-2657, which have targeted organizations across sectors including healthcare, manufacturing, and food services to alter direct-deposit details and reroute employee pay to attacker-controlled bank accounts.
After gaining access, the actors use Microsoft Graph API queries to enumerate directory users and identify payroll-related roles, leaving little or no endpoint evidence and shifting detection to Microsoft Entra sign-in telemetry and Graph activity logs. Investigators observed authentication traffic from U.S. mobile carrier IP ranges and follow-on directory reconnaissance from Canadian residential ISP addresses, suggesting proxy-backed operations; defenders were urged to enable Graph logging, revoke compromised sessions and tokens, tighten Conditional Access, deploy phishing-resistant MFA such as FIDO2 or Windows Hello for Business, audit OAuth consent and enterprise applications for persistence, and review payroll changes made during the compromise window.
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2 events from the most recent confirmed update back to the earliest known activity.
Microsoft links campaign activity to Storm-2755 and Storm-2657
Microsoft attributed the observed Microsoft 365 and Graph-based reconnaissance activity to the threat clusters Storm-2755 and Storm-2657. The reporting says these actors have targeted multiple industries, including healthcare, manufacturing, and food services, for direct financial theft.
SRA identifies active Payroll Pirate campaign targeting payroll functions
SecurityRisk Advisors reported an active campaign dubbed Payroll Pirate that uses phishing and adversary-in-the-middle session hijacking to compromise Microsoft 365 accounts tied to HR, payroll, administrative, and finance functions in order to redirect employee salary payments. After takeover, the attackers use Microsoft Graph API queries to enumerate directories and identify payroll-related personnel while leaving little or no endpoint footprint.
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Storm-2755 Hijacks Microsoft 365 Sessions to Redirect Payroll Deposits
Microsoft said the financially motivated threat actor **Storm-2755** targeted Canadian employees in payroll diversion attacks by compromising Microsoft 365 accounts and changing salary payments to attacker-controlled bank accounts. The campaign used SEO poisoning and malvertising to lure victims to `bluegraintours[.]com`, where an adversary-in-the-middle phishing flow captured credentials, session cookies, and OAuth tokens, allowing the attackers to bypass MFA through token replay and gain persistent access to victim accounts. After entering compromised tenants, Storm-2755 searched for payroll and HR workflows, created inbox rules to hide messages about direct-deposit or banking changes, and in some cases manually accessed HR SaaS platforms such as **Workday** to alter payment details. Microsoft reported indicators including Entra error code `50199`, a user-agent shift to **Axios 1.7.9** with the same session ID, and recurring non-interactive **OfficeHome** sign-ins about every 30 minutes; the company said it assisted affected organizations, carried out tenant takedowns, and urged defenses including phishing-resistant MFA, token revocation, Conditional Access, continuous access evaluation, suspicious inbox-rule monitoring, and device compliance enforcement.
May 25, 2026
Payroll Pirate Phishing Attacks Targeting US University Employees
Cybercriminals identified as 'payroll pirates' have launched a targeted phishing campaign against US universities, aiming to divert salary payments from employees to accounts under their control. Microsoft Threat Intelligence reported that since March 2025, at least 11 accounts across three universities were successfully compromised, with phishing emails sent to nearly 6,000 recipients at 25 different universities. The attackers primarily targeted third-party platforms such as Workday, which are commonly used for HR and payroll management in higher education institutions. The phishing emails often contained malicious links and were crafted to steal multifactor authentication (MFA) codes, enabling the attackers to bypass security measures and hijack employee accounts. Once inside a compromised account, the threat actors established inbox rules to automatically delete warning emails from Workday, thereby concealing unauthorized changes to bank account information. This allowed the attackers to redirect salary payments without immediate detection by the victims. The phishing lures were varied, with some emails referencing COVID-19 exposure or faculty misconduct, and often included links to Google Docs to increase credibility. In one instance, a phishing email about illness exposure was sent to 500 individuals at a single organization. Microsoft attributed the campaign to a group it tracks as Storm-2657 and has proactively contacted affected customers with mitigation advice. The campaign demonstrates a sophisticated understanding of university HR processes and leverages social engineering themes relevant to academic environments. The attackers' use of MFA code theft highlights the evolving tactics used to bypass common security controls. Microsoft emphasized that while Workday was a primary target, other HR and payment systems could also be at risk. The scale of the campaign, with thousands of potential victims, underscores the need for heightened vigilance and improved security awareness among university staff. The incident has raised concerns about the security of third-party platforms used for payroll and HR functions in the education sector. Workday, the platform most frequently targeted, did not respond to requests for comment regarding the incident. Microsoft’s response included sharing technical indicators and recommended best practices to help organizations defend against similar attacks. The campaign is ongoing, and universities are urged to review their security protocols, especially around MFA and email filtering. The incident highlights the persistent threat of phishing and the importance of layered security defenses in protecting sensitive financial information.
May 1, 2026
Microsoft phishing campaign stole auth tokens from 35,000 users
Microsoft disclosed a large-scale phishing campaign that targeted more than **35,000 users** at over **13,000 organizations** across **26 countries**, with most victims in the United States and concentrations in healthcare, life sciences, financial services, professional services, and technology. The operation used code-of-conduct and compliance-themed emails delivered through legitimate email services, including abuse of platforms such as Amazon SES, to make messages appear trustworthy and help them pass common email authentication checks. Victims received PDF attachments containing links that led through fake CAPTCHA and document-review pages before landing on spoofed Microsoft sign-in portals. Microsoft said the attackers used an **adversary-in-the-middle** phishing flow to capture credentials and authentication tokens in real time, allowing them to bypass weak multifactor authentication and gain immediate account access. The company described the activity as one of the most sophisticated code-of-conduct-themed credential theft campaigns it has observed and said it reflects broader trends including CAPTCHA-gated phishing, QR-code phishing, and phishing-as-a-service ecosystems such as **Tycoon 2FA**, **Kratos**, and **EvilTokens**. Microsoft urged organizations to strengthen defenses with Defender for Office 365, SmartScreen-enabled browsers, phishing awareness training, stronger authentication, conditional access policies, and automated attack disruption in Defender XDR.
May 5, 2026