March 2025

Security researcher Wietze Beukema revealed vulnerabilities in Windows LK shortcut files at the Wild West Hackin' Fest, which could allow attackers to deploy harmful payloads. He identified four undocumented techniques that manipulate these shortcut files, obscuring malicious targets from users. The vulnerabilities exploit inconsistencies in how Windows Explorer handles conflicting target paths, allowing for deceptive file properties. One technique involves using forbidden Windows path characters to create misleading paths, while another manipulates LinkTargetIDList values. The most sophisticated method alters the EnvironmentVariableDataBlock structure to present a false target in the properties window while executing malicious commands in the background. Microsoft declined to classify the EnvironmentVariableDataBlock issue as a security vulnerability, stating that exploitation requires user interaction and does not breach security boundaries. They emphasized that Windows recognizes shortcut files as potentially dangerous and provides warnings when opening them. However, Beukema noted that users often ignore these warnings. The vulnerabilities share similarities with CVE-2025-9491, which has been exploited by various state-sponsored and cybercrime groups. Microsoft initially did not address CVE-2025-9491 but later modified LNK files to mitigate the vulnerability after it was widely exploited.