CVE-2011-0673 in Windows
Summary
by MITRE
win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP3 allows local users to gain privileges via a crafted application that triggers a NULL pointer dereference, aka "Win32k Null Pointer De-reference Vulnerability."
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Analysis
by VulDB Data Team • 01/18/2025
The CVE-2011-0673 vulnerability represents a critical privilege escalation flaw within the Windows kernel-mode driver subsystem, specifically targeting the win32k.sys component that manages user interface elements and graphics operations. This vulnerability exists in Microsoft Windows XP Service Pack 3 and demonstrates how kernel-mode memory management flaws can be exploited to elevate privileges from standard user level to system level access. The vulnerability stems from improper handling of null pointer references within the win32k.sys driver, which is responsible for processing graphical user interface operations including window management, graphics rendering, and input handling functions that are integral to the Windows desktop experience.
The technical exploitation of this vulnerability occurs when a local attacker crafts a malicious application that triggers a NULL pointer dereference condition within the win32k.sys driver. When the driver attempts to access a null pointer during kernel execution, the system crashes or behaves unpredictably, allowing the attacker to manipulate the execution flow and potentially execute arbitrary code with elevated privileges. This type of vulnerability falls under CWE-476, which specifically addresses NULL pointer dereference conditions, and aligns with ATT&CK technique T1068, which covers exploit for privilege escalation. The flaw exploits the kernel-mode execution environment where any error in memory management can result in complete system compromise, as the driver operates with the highest privilege level in the system.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to gain full system control without requiring network connectivity or external attack vectors. Local users who can execute code on the target system can leverage this vulnerability to bypass security controls, install malware, modify system files, and establish persistent access. The vulnerability is particularly dangerous because it requires no special network access or complex attack chains, making it a preferred target for attackers seeking to establish footholds on compromised systems. The affected win32k.sys driver handles critical user interface operations that are constantly active during normal system operation, making the exploitation window frequent and persistent.
Mitigation strategies for CVE-2011-0673 primarily involve immediate application of Microsoft security patches and updates, as the vendor released specific fixes for this vulnerability through regular security updates. System administrators should implement comprehensive patch management processes to ensure all affected Windows XP systems receive the necessary updates promptly. Additional defensive measures include implementing least privilege principles to limit local user access, monitoring for suspicious process behavior related to kernel-mode operations, and deploying kernel-mode exploit detection tools that can identify attempts to trigger NULL pointer dereference conditions. Network segmentation and application whitelisting can further reduce the attack surface by limiting the ability of local attackers to execute malicious applications. Organizations should also consider migrating away from unsupported Windows XP systems, as Microsoft ended support for this operating system in 2014, leaving systems vulnerable to unpatched exploits like CVE-2011-0673.