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CISA Urges Organizations to Patch Exploited Windows Vulnerability

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has expanded its list of vulnerabilities known to be exploited in malicious attacks with a recently addressed Windows zero-day flaw.

Tracked as CVE-2022-21882, the high-severity security hole was fixed on January 2022 Patch Tuesday, when Microsoft said it was aware of limited, targeted exploitation attempts.

Identified in the Win32k.sys driver, the issue is described as an elevation of privilege bug that could allow a local, authenticated attacker to obtain system or administrative rights.

Security researcher RyeLv, who received acknowledgement for the find, says CVE-2022-21882 is in fact a bypass for the patch that Microsoft released in February 2021 for CVE-2021-1732, another exploited Win32k vulnerability.

CVE-2022-21882, the researcher explains, allows an attacker to call a GUI API in user mode to make calls to specific kernel functions, intercept the triggered callback, and then modify the window type.

Because no check was in place to identify window type changes, the wrong data was being referenced due to type confusion, and the attacker could cause an out-of-bounds read and write.

An attacker can trigger the vulnerability to “modify the kernel object of another window to obtain the kernel arbitrary address read and write primitive,” the researcher explains.

Microsoft’s patch adds the necessary check to identify window type changes.

[READ: Patch Tuesday: Microsoft Calls Attention to 'Wormable' Windows Flaw]

Roughly two weeks after the patches were released, Gil Dabah, founder and CEO of Privacy Piiano, released proof-of-concept (PoC) code targeting the security flaw. He claims he identified the bug a couple of years ago but did not report it.

In April 2020, the Israeli security researcher published a paper on more than 25 vulnerabilities affecting the user interface win32 kernel (win32k) component, warning that all versions of Windows are impacted.

Approximately one week after Dabah made the PoC public, CISA announced it has added CVE-2022-21882 to its ‘Must Patch’ vulnerability catalog, urging federal agencies and other organizations to apply the available patch as soon as possible.

“These types of vulnerabilities are a frequent attack vector for malicious cyber actors of all types and pose significant risk to the federal enterprise,” CISA says.

In line with binding operational directive (BOD) 22-01, which was released alongside the Known Exploited Vulnerabilities Catalog, federal agencies have two weeks to patch their systems against CVE-2022-21882.

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