Researcher With a Grudge Drops Windows 0-Day That Hands Out System Rights
Nightmare Eclipse, a researcher locked in a public feud with Microsoft, has released SignDrop, a Windows zero-day that lets ordinary users seize full System privileges. It abuses the Common Log File System and Windows Defender to turn a normal log file into a privilege-escalation weapon.
- Original source: arstechnica.com.
- The source published it on Nov 13, 2026 at 4:26 PM.
- No second outlet has reported it yet. Treat it as a single-source claim.
Nightmare Eclipse — the pseudonym of a researcher who has been publicly feuding with Microsoft — disclosed SignDrop on Tuesday. According to Ars Technica, the flaw grants local users full System rights on some versions of Windows, the highest level of access on the machine.
The bug lives 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." An attacker with nothing more than ordinary user rights can force a privileged process, such as Windows Defender, to open a crafted CLFS container, then abuse the privileged file creation to climb to System.
The trick works by chaining three things together: CLFS, Windows Defender, and Windows file permissions. The exploit leans on Defender to open a log file that a standard user created, by calling ServerMpUpdateEngineSignature — a legitimate Defender function used to process antivirus signature updates.
TopicsNightmare Eclipse · SignDrop · Microsoft · Windows · Common Log File System · Windows Defender · Ars Technica
Source: arstechnica.com
Written by Paparazzi with AI. Not financial advice.
More stories
- Tech & AIcryptobriefing.com0viewsVon der Leyen puts €500B price tag on Europe's computing gap
- Tech & AIx.com0viewsNvidia said to approach Arm CEO Rene Haas as possible Jensen Huang successor
- Tech & AInewsbtc.com0viewsHyperscalers charge nearly double the going rate for GPU hours, Fluence finds
- Tech & AIcryptobriefing.com0viewsDimon and Amodei Share a Stage as Anthropic's IPO Clock Runs Down