#VU1116 Privilege escalation in Windows and Windows Server - CVE-2016-7255

Vulnerability identifier: #VU1116

Vulnerability risk: Medium

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:Green]

CVE-ID: CVE-2016-7255

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 gain elevated privileges on the target system.

The weakness is due to improper handling of objects in memory by win32k.sys. By sending a specially crafted system call NtSetWindowLongPtr(), a local attacker can set index GWLP_ID to WS_CHILD value on a window handle with GWL_STYLE and execute arbitrary code with system privileges.

Successful explotation of the vulnerability results in privilege escalation.

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

Mitigation
Install update from vendor's website.

Vulnerable software versions

Windows: Vista, 7, 8.1 RT - 8.1, 10

Windows Server: 2008 R2 - 2008, 2012 R2 - 2012, 2016 10.0.14393.10

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External links
https://security.googleblog.com/2016/10/disclosing-vulnerabilities-to-protect.html
https://technet.microsoft.com/library/security/MS16-135

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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.