CVE-2016-7211 in Windows
Summary
by MITRE
The kernel-mode drivers in 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, and Windows 10 Gold, 1511, and 1607 allow local users to gain privileges via a crafted application, aka "Win32k Elevation of Privilege Vulnerability." a different vulnerability than CVE-2016-3266, CVE-2016-3376, and CVE-2016-7185.
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Analysis
by VulDB Data Team • 09/23/2022
The vulnerability identified as CVE-2016-7211 represents a critical privilege escalation flaw within the Windows kernel-mode drivers, specifically affecting multiple versions of the microsoft windows operating system. This vulnerability resides in the win32k.sys driver which handles user-mode graphics operations and is responsible for managing the windows graphical subsystem. The flaw allows local attackers with standard user privileges to execute malicious code that can elevate their privileges to system level, effectively compromising the entire operating system. This vulnerability is particularly concerning because it operates at the kernel level where all system operations are processed, making it a prime target for exploitation by malware authors and advanced persistent threat actors.
The technical implementation of this vulnerability stems from improper validation of user-mode input within the win32k.sys driver. When a crafted application interacts with the graphics subsystem, it can trigger a memory corruption condition that allows an attacker to manipulate kernel memory structures. This flaw specifically relates to how the driver processes certain graphics objects and handles memory allocation during user-mode to kernel-mode transitions. The vulnerability is classified under common weakness enumeration CWE-121 as a heap-based buffer overflow, where insufficient bounds checking allows an attacker to overwrite adjacent memory locations. The exploitation mechanism relies on the ability to control memory layout through carefully crafted graphics operations that bypass normal input validation procedures.
The operational impact of CVE-2016-7211 is severe and multifaceted, as it provides attackers with complete system compromise capabilities. Once successfully exploited, the vulnerability enables attackers to execute arbitrary code with kernel-level privileges, allowing them to bypass all standard security controls including user access control, data execution prevention, and other operating system security mechanisms. This privilege escalation can result in full system compromise, data exfiltration, persistence mechanisms installation, and the ability to manipulate system files and registry entries. The vulnerability affects a broad range of windows operating systems including vista, server 2008, windows 7, 8.1, and various server editions, making it particularly dangerous in enterprise environments where these systems are commonly deployed. The attack vector requires local access but does not require network connectivity, making it difficult to detect through traditional network-based monitoring systems.
Mitigation strategies for CVE-2016-7211 should prioritize immediate patch deployment as microsoft released security updates addressing this vulnerability through regular security bulletins. Organizations should implement comprehensive patch management processes to ensure all affected systems receive the necessary updates promptly. Additional defensive measures include enabling exploit protection features such as application control policies, disabling unnecessary graphics services, and implementing monitoring for suspicious graphics-related processes. The vulnerability aligns with tactics described in the attack framework under technique t1068 for exploit for privilege escalation, and t1059 for command and scripting interpreter. Network administrators should monitor for unusual graphics processing activity and implement user behavior analytics to detect potential exploitation attempts. System hardening practices such as disabling legacy graphics drivers, restricting user privileges, and implementing least privilege access controls can significantly reduce the attack surface for this vulnerability. Organizations should also consider implementing intrusion detection systems that can identify anomalous behavior patterns consistent with privilege escalation attacks targeting kernel-mode components.