CVE-2016-7255

Deeper analysis

The vulnerability is an elevation of privilege flaw in the kernel-mode drivers of the Win32k component, tracked as CVE-2016-7255. It affects Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold/1511/1607, and Windows Server 2016. The issue permits local users to gain privileges through a crafted application, carrying a CVSS 3.1 base score of 7.8 under an AV:L/AC:L/PR:N/UI:R vector.

Local attackers with the ability to run code on an affected system can exploit the flaw to escalate privileges, typically by supplying a malicious application that triggers improper handling in win32k.sys. Successful exploitation yields higher access rights on the target host, potentially enabling further actions such as installing persistent malware or accessing sensitive resources.

Microsoft security bulletin MS16-135 addresses the issue with patches for the listed Windows versions. Additional references, including Trend Micro analysis and public exploit disclosures on Packet Storm, indicate that mitigation centers on applying the vendor updates promptly, as no configuration workarounds are highlighted in the primary advisory.

The vulnerability has seen real-world exploitation, with public reports documenting in-the-wild attacks leveraging the one-bit manipulation technique in win32k to achieve privilege escalation on unpatched systems.