Since October 2024, Microsoft Defender Experts has observed and helped multiple customers address campaigns leveraging Node.js to deliver malware and other payloads that ultimately lead to information theft and data exfiltration.
Exchange Server and SharePoint Server are business-critical assets and considered crown-jewels for many organizations, making them attractive targets for attacks.
Microsoft Threat Intelligence Center (MSTIC) and Microsoft Security Response Center (MSRC) have discovered post-compromise exploitation of a newly discovered zero-day vulnerability in the Windows Common Log File System (CLFS) against a small number of targets. Microsoft released security updates to address the vulnerability, tracked as CVE 2025-29824, on April 8, 2025.
As Tax Day approaches in the United States on April 15, Microsoft has detected several tax-themed phishing campaigns employing various tactics. These campaigns use malicious hyperlinks and attachments to deliver credential phishing and malware including RaccoonO365, AHKBot, Latrodectus, BruteRatel C4 (BRc4), and Remcos.
Using Microsoft Security Copilot to expedite the discovery process, Microsoft has uncovered several vulnerabilities in multiple open-source bootloaders impacting all operating systems relying on Unified Extensible Firmware Interface (UEFI) Secure Boot.
Microsoft Incident Response uncovered a novel remote access trojan (RAT) named StilachiRAT, which demonstrates sophisticated techniques to evade detection, persist in the target environment, and exfiltrate sensitive data. This blog primarily focuses on analysis of the WWStartupCtrl64.
Starting in December 2024, leading up to some of the busiest travel days, Microsoft Threat Intelligence identified a phishing campaign that impersonates online travel agency Booking.com and targets organizations in the hospitality industry. The campaign uses a social engineering technique called ClickFix to deliver multiple credential-stealing malware in order to conduct financial fraud and theft.
Microsoft Threat Intelligence has uncovered a new variant of XCSSET, a sophisticated modular macOS malware that infects Xcode projects, in the wild. Its first known variant since 2022, this latest XCSSET malware features enhanced obfuscation methods, updated persistence mechanisms, and new infection strategies.
Microsoft detected a large-scale malvertising campaign in early December 2024 that impacted nearly one million devices globally. The attack originated from illegal streaming websites embedded with malvertising redirectors and ultimately redirected users to GitHub to deliver initial access payloads as the start of a modular and multi-stage attack chain.
Silk Typhoon is a Chinese state actor focused on espionage campaigns targeting a wide range of industries in the US and throughout the world. In recent months, Silk Typhoon has shifted to performing IT supply chain attacks to gain access to targets.
Microsoft Threat Intelligence Center discovered an active and successful device code phishing campaign by a threat actor we track as Storm-2372. Our ongoing investigation indicates that this campaign has been active since August 2024 with the actor creating lures that resemble messaging app experiences including WhatsApp, Signal, and Microsoft Teams.
Microsoft is publishing for the first time our research into a subgroup within the Russian state actor Seashell Blizzard and its multiyear initial access operation, tracked by Microsoft Threat Intelligence as the “BadPilot campaign”.
