#VU48060 Buffer overflow in Windows and Windows Server - CVE-2020-17087

Vulnerability identifier: #VU48060

Vulnerability risk: High

CVSSv4.0: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Amber]

CVE-ID: CVE-2020-17087

CWE-ID: CWE-119

Exploitation vector: Local

Exploit availability: Yes

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 privilege son the system.

The vulnerability exists due to a boundary error within the Windows Kernel Cryptography Driver cng.sys, which exposes a "\Device\CNG" device to user-mode programs and supports a variety of IOCTLs with non-trivial input structures. A local user can run a specially crafted program to trigger memory corruption and execute arbitrary code on the system with elevated privileges.

Note, this vulnerability is being actively exploited in the wild.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Windows: 7 SP1 - 7, 8 - 8.1, 10 Gold, 10 1511 10.0.10586.3, 10 1703 10.0.15063.138, 10 1709 10.0.16299.19, 10 1803 10.0.17134.48, 10 1809 10.0.17763.1, 10 1903 10.0.18362.116, 10 1909 10.0.18363.476, 10 2004 10.0.19041.264, 10

Windows Server: 2008 R2 SP1 - 2008, 2012 Gold - 2012, 2016 10.0.14393.10, 2019 10.0.17763.1 - 2019 2004

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External links
https://bugs.chromium.org/p/project-zero/issues/detail?id=2104
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-17087

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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.