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.
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How this story unfolded
4 events from the most recent confirmed update back to the earliest known activity.
Microsoft responds to Storm-2755 campaign with takedowns and guidance
By April 9, 2026, Microsoft said it had worked with affected organizations and carried out tenant takedowns related to the Storm-2755 activity. It also published detection details and recommended mitigations including phishing-resistant MFA, token revocation, Conditional Access, continuous access evaluation, and monitoring for suspicious inbox rules.
Storm-2755 conducts payroll diversion attacks against Canadian users
Microsoft reported that threat actor Storm-2755 targeted Canadian employees by luring them through SEO poisoning and malvertising to a phishing domain, then stealing credentials, session cookies, and OAuth tokens to access Microsoft 365 accounts and redirect payroll deposits. After compromise, the actor searched for payroll and HR processes, created inbox rules to hide banking-change messages, and in some cases accessed HR SaaS platforms such as Workday to alter payment details.
Dark Storm claims responsibility for attack on X
After the March 10 outages, the pro-Palestinian hacktivist group Dark Storm claimed on Telegram that it had carried out a DDoS attack against X and shared Check Host screenshots as purported evidence. The reporting noted that the claim did not independently verify attribution.
X suffers multiple outages amid suspected DDoS attack
On March 10, 2025, X experienced multiple service outages that Elon Musk said were caused by a massive cyberattack, possibly involving a large coordinated group or a country.
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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.
Jun 15, 2026
Storm-2949 Turned Entra ID Account Takeovers Into a Cloud-Wide Azure Breach
Microsoft reported that **Storm-2949** used social engineering and abuse of Microsoft **Self-Service Password Reset (SSPR)** to compromise multiple **Microsoft Entra ID** accounts, including accounts tied to IT staff and senior leadership, then expanded access across **Microsoft 365** and **Azure**. After the initial identity takeover, the actor conducted tenant discovery through the **Microsoft Graph API**, exfiltrated data from **OneDrive** and **SharePoint**, and sought persistence by re-registering MFA methods and attempting to abuse service principal credentials. The intrusion then moved deeper into Azure, where Storm-2949 relied on legitimate management-plane operations and privileged **Azure RBAC** roles to access **App Services**, **Key Vault**, **SQL databases**, **Storage accounts**, and **virtual machines**. Microsoft said the actor used publish profiles, Key Vault permission changes, SQL firewall rule modifications, storage key listing, **VMAccess**, and **Run Command** to harvest credentials, execute code, deploy **ScreenConnect** on VMs, weaken Microsoft Defender Antivirus, and exfiltrate large volumes of data while blending into normal administrative activity; the group also cleared event logs and deleted artifacts to hinder detection.
May 23, 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