Microsoft has warned of several phishing campaigns exploiting tax-related themes to distribute malware and steal credentials. These campaigns use URL shorteners, QR codes, and malicious attachments to evade detection. The attacks leverage phishing-as-a-service (PhaaS) platforms, such as RaccoonO365, and distribute remote access trojans like Remcos RAT, as well as other post-exploitation malware such as Latrodectus, AHKBot, and GuLoader.
One campaign, identified in February 2025, sent hundreds of tax-themed phishing emails aimed at U.S. targets.
The phishing emails often included PDF attachments with links redirecting users to fake Docusign pages. These pages attempted to trick victims into downloading malware like BRc4 or Latrodectus via JavaScript files and MSI installers. In one attack, the victim’s system or IP address determined whether they were redirected to a benign PDF or exposed to malware. Microsoft also detected a second wave of phishing emails targeting over 2,300 U.S. organizations, with a particular focus on IT, engineering, and consulting sectors.
In another form of phishing, emails contained QR codes that linked to phishing pages mimicking Microsoft 365 login screens, tricking users into entering credentials.
Other campaigns used AHKBot and GuLoader to deploy additional malware. AHKBot infections began with malicious Microsoft Excel files containing macros that, when enabled, downloaded an AutoHotKey script. This script captured screenshots and exfiltrated them to remote servers, while GuLoader delivered a .bat file and installed Remcos.
These attacks are part of a broader surge in phishing and social engineering tactics that have targeted Europe and the U.S. over the past few weeks. Researchers have also observed a rise in campaigns using QR codes to disguise malicious URLs, redirecting victims via open redirects on legitimate websites. To defend against these threats, experts advise adopting phishing-resistant authentication methods and using security tools that block malicious domains and websites
