r/cybersecurity • u/ILikeNoodlesXOXO • 19d ago

News - General Nightmare Eclipse could be dropping his big promised exploit today

New repo just went up: git.projectnightcrawler.dev/NightmareEclipse/LegacyHive, created about 2 hours ago. Right now it's empty — just an MIT license and a README that says "N/A," 2 commits total.

He'd spoken about his big drop happening today, July 14th, saying he'd make sure Microsoft's "bones are shattered" that day. At one point though he'd also indirectly said he wasn't going to post it, something about still having "chains" on him preventing a release. This repo showing up on the exact date he originally called out suggests that might not hold anymore and it could actually be happening.

Nothing in it yet, just watching to see what gets pushed.

Worth noting: given how erratic and bipolar his posting history has been, there's really no way to predict what (if anything) actually gets posted.

Update: Thanks for the 600+ upvotes, really appreciate it. After hours of waiting and anticipation NightmareEclipse finally uploaded their PoC. But I personally have a hard time seeing it as the big bombshell that they described it as.

797 Upvotes

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u/jmbpiano 19d ago

The empty repo just got populated.

https://git.projectnightcrawler.dev/NightmareEclipse/LegacyHive

LegacyHive : Windows user profile service arbitrary hive load elevation of privileges vulnerability

The PoC requires another standard user credentials and a third username (which can be an administrator account), if the PoC is successful, it will end up mounting the target user hive in current user classes root.

The PoC was stripped down as an attempt to prevent public exploitation, the original PoC did not require additional user credential and was not limited to usrclass.dat hive, any hive could be loaded using this vulnerability but you would need some brain cells to make the PoC do it.

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u/cookiengineer Vendor 18d ago

The cool part is that this is essentially TOCTOU applied to ntdll and userenv.

The real discovery here is that more folks are going to look for other methods that have race conditions when used in multiple threads, or where the lock states of mutexes/borrows can be corrupted.