CVE-2011-1233 in Windows
Summary
by MITRE
win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 allows local users to gain privileges via a crafted application that triggers a NULL pointer dereference, a different vulnerability than other "Vulnerability Type 2" CVEs listed in MS11-034, aka "Win32k Null Pointer De-reference Vulnerability."
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Analysis
by VulDB Data Team • 04/20/2025
The vulnerability identified as CVE-2011-1233 represents a critical privilege escalation flaw within the Windows kernel-mode driver component known as win32k.sys. This vulnerability affects multiple versions of Microsoft Windows including Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, R2, and R2 SP1, as well as Windows 7 Gold and SP1. The flaw manifests specifically within the kernel-mode drivers that handle user interface operations, making it particularly dangerous as it operates at the most privileged level of the operating system. The vulnerability is categorized under CWE-476 which specifically addresses NULL pointer dereference conditions, a fundamental programming error that can lead to system instability and unauthorized privilege escalation. This classification aligns with the broader ATT&CK framework's privilege escalation techniques where adversaries seek to gain higher-level permissions within the target system.
The technical mechanism of this vulnerability involves a crafted application that triggers a NULL pointer dereference within the win32k.sys driver. When the operating system processes certain user interface operations through this kernel driver, it fails to properly validate pointer references, leading to a situation where a NULL pointer is dereferenced. This condition occurs in the context of kernel-mode execution where the system's memory management and privilege controls are actively engaged. The flaw specifically exploits how the win32k.sys driver handles certain input parameters during user interface rendering operations, particularly when dealing with window management functions. The vulnerability is distinct from other "Vulnerability Type 2" issues referenced in MS11-034, indicating that while related, this particular flaw has unique triggering conditions and execution paths that make it particularly susceptible to exploitation by local attackers who can craft malicious applications to trigger the specific memory access violation.
The operational impact of CVE-2011-1233 is severe and directly affects the security posture of affected systems. Local attackers who successfully exploit this vulnerability can achieve privilege escalation from standard user level to kernel-level execution, effectively granting them complete control over the target system. This elevation of privileges allows attackers to bypass all standard security controls, including user access controls, file permissions, and other system-level protections. Once exploited, the attacker can execute arbitrary code with the highest system privileges, potentially leading to complete system compromise, data exfiltration, or establishment of persistent backdoors. The vulnerability's presence in multiple Windows versions means that organizations running any of the affected operating systems are at risk, with the potential for widespread impact across enterprise networks where these systems are deployed. The fact that this is a local privilege escalation vulnerability means that attackers do not require network access or external attack vectors to exploit the flaw, making it particularly concerning for environments where user access is not strictly controlled.
Mitigation strategies for CVE-2011-1233 should focus on immediate patch deployment as the primary defense mechanism, with Microsoft releasing security updates through the regular patching cycle. Organizations should prioritize patching all affected Windows systems, particularly those running the supported versions mentioned in the vulnerability description. Additionally, implementing application whitelisting policies can help prevent the execution of malicious applications designed to trigger this vulnerability. System administrators should also consider implementing enhanced monitoring for unusual kernel-mode activities and user interface operations that might indicate exploitation attempts. The vulnerability's nature as a kernel-mode flaw means that traditional endpoint protection solutions may not provide complete coverage, requiring more comprehensive security approaches including regular system hardening practices, network segmentation, and strict access control policies. Organizations should also maintain current threat intelligence feeds to stay informed about any exploitation attempts targeting this specific vulnerability, as the ATT&CK framework suggests that adversaries often leverage such vulnerabilities for initial access or privilege escalation within compromised environments.