Microsoft released several patches for multiple vulnerabilities during the Patch Tuesday for August 2024. One of the vulnerabilities listed by Microsoft was the CVE-2024-38106.
This vulnerability is associated with Windows Kernel Privilege Escalation affecting multiple Microsoft Windows OSes including Windows 10, 11 and Windows Server (2016, 2019, 2022).
Moreover, Microsoft stated that this vulnerability was actively exploited by threat actors.
As a matter of fact, Microsoft also mentioned that no user interaction was required for exploiting this vulnerability.
The severity for this vulnerability was given as 7.0 (High).
Technical Analysis – CVE-2024-38106
According to the reports shared with Cyber Security News, CVE-2024-38106 was linked to a race condition.
Successful exploitation of this vulnerability could lead to the threat actor gaining SYSTEM level privileges on the affected system.
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Further, it was stated that the vulnerability was a little complex to exploit.
Researchers at Pixiepoint investigated the patch for this vulnerability. It was revealed that the fix was made on the ntoskrnl.exe that was also responsible for several other bugs fixed by Microsoft.
On analyzing further, there were two security changes made to the functions VslGetSetSecureContext() and NtSetInformationWorkerFactory().
VslGetSetSecureContext() was implemented with a fix to mitigate a race condition. This was done by making the function properly lock the VslpEnterIumSecureMode() operation that was related to the VBS secure kernel.
NtSetInformationWorkerFactory() was implemented with a similar fix for mitigating a race condition.
However, here it was done by adding a flag inside NtShutdownWorkerFactory() –> ExpShutdownWorkerFactory():
However, the proof of concept code can be found below. As per the proof of concept, it triggers calling the NtClose() on worker factory object handles to achieve a vulnerable state.
This will result in reaching KiInsertTimer2WithCollectionLockHeld() worker factory object and freeing the associated timer.
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Organizations should apply the necessary patches to vulnerable products to prevent them from being exploited.
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