Attackers Windows vulnerability to gain admin privilege.

THREAT LEVEL: Red.

For a detailed advisory, download the pdf file here.

Microsoft fixed a privilege escalation vulnerability, CVE-2022-21882, in their January 2022 patch Tuesday release that impacts Windows 10 and Windows Server 2019 if successfully exploited.

CVE-2022-21882 is a vulnerability that allows an attacker with limited access to a compromised device to get administrative privileges, propagate across the network, create new administrators, and execute privileged commands. This is a workaround for the previously patched and actively exploited flaw CVE-2021-1732, which was fixed a year ago that affects Windows 10, Windows 11, Windows Server 2019, and Windows Server 2022. Full exploits, on the other hand, only affected Windows 10 and Windows Server 2019. A Proof of Concept(PoC) for this vulnerability has recently been released by the researchers due to their frustration with Microsoft’s bug bounty program.

The following is the exploitation flow:

1. To exploit the issue and obtain an out-of-bounds write, change the cbWndExtra of the window object to 0x0FFFEFFF, allowing the window object WndExtra to access huge amounts of memory.

2. Change the WS_CHILD flag of another window and assign it a specially generated Menu (fake menu).

3. Using the GetMenuBarInfo API and a false menu, get any arbitrary read primitive.

4. To obtain an arbitrary write primitive, use the SetWindowLongPtrA API to alter the ExtraBytes of another window object.

5. Using EPROCESS ActiveProcessLinks, detect the system eprocess with PID 4.

6. Replace the current process token with the system token.

Organizations should apply the patches as soon as possible to avoid exploitation.