CVE-2017-8666 in Windows
Summary
by MITRE
Microsoft Win32k in 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 1703, and Windows Server 2016 allows an information disclosure vulnerability when it fails to properly handle objects in memory, aka "Win32k Information Disclosure Vulnerability".
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Analysis
by VulDB Data Team • 01/08/2021
The CVE-2017-8666 vulnerability represents a critical information disclosure flaw within the Windows kernel-mode driver subsystem known as Win32k.sys. This vulnerability affects a broad range of Microsoft Windows operating systems including server and client versions from Windows Server 2008 through Windows 10 version 1703. The flaw resides in how the Win32k component processes memory objects, specifically failing to properly validate or handle certain kernel-mode structures during normal operation. The vulnerability is categorized under CWE-200, which represents "Information Exposure" and aligns with the broader category of privilege escalation vulnerabilities that can lead to unauthorized access to sensitive system information.
The technical implementation of this vulnerability occurs within the graphics subsystem of Windows, where Win32k.sys manages user interface objects and graphics rendering operations. When the system processes certain graphics operations or handles memory objects in an improper state, the kernel fails to properly validate memory access patterns, leading to potential information disclosure. Attackers can exploit this by crafting malicious graphics operations or user interface interactions that trigger the flawed memory handling code path. The vulnerability does not require elevated privileges to exploit and can be triggered through normal user interactions with graphics-intensive applications or by manipulating the graphics subsystem through legitimate system interfaces.
From an operational impact perspective, this vulnerability poses significant security risks to enterprise environments and individual users alike. The information disclosure aspect means that an attacker could potentially extract sensitive kernel memory contents including credentials, encryption keys, or other confidential system data. The vulnerability's presence across multiple Windows versions creates widespread exposure, affecting both server and desktop environments. According to ATT&CK framework, this vulnerability maps to T1068 "Exploitation for Privilege Escalation" and T1005 "Data from Local System" techniques, as it enables attackers to extract information from system memory that could facilitate further exploitation or lateral movement within networks. Organizations running affected systems face potential data breaches and compromise of sensitive information.
Mitigation strategies for CVE-2017-8666 primarily involve applying Microsoft security updates released in August 2017 as part of the monthly patch Tuesday cycle. Organizations should prioritize immediate deployment of the relevant security patches, particularly for systems handling sensitive data or serving as targets for advanced persistent threats. Additional defensive measures include implementing network segmentation to limit lateral movement, monitoring for suspicious graphics-related system calls, and deploying endpoint protection solutions that can detect anomalous behavior in kernel-mode operations. The vulnerability's exploitation potential makes it a high-priority target for threat actors, particularly in environments where traditional security controls may be insufficient to prevent exploitation. System administrators should also consider implementing application whitelisting policies to prevent execution of potentially malicious graphics processing operations that could trigger the vulnerability.