#VU53910 Security restrictions bypass in Windows and Windows Server - CVE-2021-31201

Vulnerability identifier: #VU53910

Vulnerability risk: Medium

CVSSv4.0: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:A/U:Green]

CVE-ID: CVE-2021-31201

CWE-ID: CWE-264

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Windows
Operating systems & Components / Operating system
Windows Server
Operating systems & Components / Operating system

Vendor: Microsoft

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to improperly imposed security restrictions in Microsoft Enhanced Cryptographic Provider. A local user can bypass implemented security restrictions and read or modify otherwise restricted information.

Note, the vulnerability is being actively exploited in the wild and related to a zero-day vulnerability in Adobe Reader #VU53125 (CVE-2021-28550) patched on May 11.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Windows: 7, 8.1 RT - 8.1, 10 20H2 10.0.19042.572, 10 21H1 10.0.19043.985, 10 1607 10.0.14393.10, 10 1809 10.0.17763.1, 10 1909 10.0.18363.476, 10 2004 10.0.19041.264, 10

Windows Server: 2008 R2 - 2008, 2012 R2 - 2012, 2016 10.0.14393.10, 2019 10.0.17763.1 - 2019 2004

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External links
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31201

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.