HighRansomwareCVE-2025-29824
Windows SignDrop 0-Day Exploit Lets Attackers Gain SYSTEM Privileges Through CLFS Protection
Cyber Security News·Source published ·1 min read
What happened?
A public exploit called SignDrop targets a Windows security feature meant to stop attacks on the Common Log File System (CLFS). It claims to turn a normal user account into a SYSTEM account, the highest level of control on Windows. The flaw has no CVE number and no patch as of November 11, 2026. Microsoft has also not confirmed the claims. Windows SignDrop zero-day exploit A researcher using the handle MSNightmare, also known as Nightmare Eclipse, posted the proof-of-concept on GitHub on November 10, 2026. The researcher has a history of public Windows exploit drops.
Key details
- SignDrop is a local privilege escalation exploit targeting Windows CLFS driver.
- HMAC authentication was added to CLFS log files in October 2025 updates.
- Systems in learning mode or enforcement mode are claimed vulnerable.
- Attacker must already have normal user code execution on the target.
Fixes and mitigations
- Keep Windows updated and maintain standard account controls.
What to look for
- Watch for odd file creation by high-privilege processes like Windows Defender.
- Look for unexpected CLFS error codes such as ERROR_LOG_METADATA_CORRUPT.
Summarised by SecOraLens from Cyber Security News. Always read the original source before acting. How SecOraLens verifies advisories.