Nightmare Eclipse, the pseudonym of a researcher with an ongoing, very public beef with Microsoft, has dropped yet another Windows zero-day.
On Tuesday, Nightmare Eclipse disclosed SignDrop, a vulnerability that gives local users full System rights on some versions of Windows. The vulnerability resides in the Common Log File System, which Microsoft describes as a “general-purpose logging service used by software clients running in user-mode or kernel-mode.” By forcing a privileged process such as Windows Defender to open a crafted CLFS container, an attacker with ordinary user rights can abuse the privileged file creation to elevate privileges to System.
