Data Sharing Arbitrary Windows File Delete 0-day Exploit Demo

This is an exploit by @SandboxEscaper who shared it in Twitter (https://twitter.com/SandboxEscaper/status/1054744201244692485). The vulnerability allows a local attacker to cause DoS condition (as seen on the exploit demo video wherein the system file was deleted upon running the POC by a local user) on the target system, though it's possible to use for local privilege escalation via DLL hijacking.

The vulnerability exists due to improper access control on Data Sharing Service (dssvc.dll). A non-admin attacker can then abuse a new Windows service not checking permissions again to delete OS files or DLLs, replace them with malicious versions and crash the operating system.

#deletebug POC is available at: https://github.com/SandboxEscaper/randomrepo/blob/master/DeleteBug1.rar

Bug description (from exploit author @SandboxEscaper):

RpcDSSMoveFromSharedFile(handle,L"token",L"c:\\blah1\\pci.sys");

This function exposed over alpc, has a arbitrary delete vuln.

Hitting the timing was pretty annoying. But my PoC will keep rerunning until c:\windows\system32\drivers\pci.sys is deleted.

I believe it’s impossible to hit the timing on a single core VM. I was able to trigger it using 4 cores on my VM. (Sadly I wasn’t able to use OPLOCKS with this particular bug)

Root cause is basically just a delete without impersonation because of an early revert to self. Should be straight forward to fix it…

Exploitation wise.. you either try to trigger dll hijacking issues in 3rd party software.. or delete temp files used by a system service in c:\windows\temp and hijack them and hopefully do some evil stuff.

https://ethicalhackers.club