CVE-2011-1231 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 • 02/02/2025
The vulnerability described in CVE-2011-1231 represents a critical privilege escalation flaw within the Windows kernel-mode driver subsystem, specifically affecting the win32k.sys component that handles graphics and user interface operations. This vulnerability exists in multiple Windows operating systems including 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 when a malicious application triggers a NULL pointer dereference condition within the win32k.sys driver, allowing local attackers to execute code with kernel-level privileges. This represents a classic kernel-mode vulnerability that leverages the trust relationship between user-mode applications and kernel-mode drivers, enabling attackers to bypass standard security boundaries and elevate their privileges from standard user to SYSTEM level access. The vulnerability is categorized under CWE-476 as a NULL pointer dereference, which occurs when software attempts to access a memory location through a pointer that has been initialized to NULL, leading to system crashes or privilege escalation opportunities. From an operational perspective, this vulnerability enables attackers to gain complete control over affected systems, as the win32k.sys driver is responsible for critical user interface functions including window management, graphics rendering, and input handling, making it a prime target for privilege escalation attacks. The impact extends beyond individual system compromise, as successful exploitation can lead to full network infiltration, data exfiltration, and persistence mechanisms. The vulnerability is particularly concerning because it operates at the kernel level, meaning that any application running with standard user privileges can potentially exploit this weakness to gain administrative access to the system. This makes it especially dangerous in enterprise environments where users may have legitimate access to systems but lack administrative rights. The attack vector requires local access to the target system, as the vulnerability cannot be exploited remotely, but this limitation does not diminish its severity given that local access can be gained through various means including phishing attacks, social engineering, or exploitation of other remote vulnerabilities. The vulnerability's classification as a "Win32k Null Pointer De-reference Vulnerability" distinguishes it from other related vulnerabilities such as those referenced in MS11-034, which focused on different aspects of the same kernel subsystem. This particular flaw aligns with ATT&CK technique T1068 which describes the use of local privilege escalation techniques to gain system-level access. Microsoft addressed this vulnerability through security updates that patched the NULL pointer dereference condition in the win32k.sys driver, requiring system administrators to apply these patches to prevent exploitation. The remediation process involves applying the appropriate security updates from Microsoft, which typically include modifications to the driver's memory management routines to properly validate pointer values before dereferencing. Organizations should implement comprehensive patch management processes to ensure timely deployment of these security updates across all affected systems, particularly given the widespread impact of this vulnerability across multiple Windows versions. The vulnerability demonstrates the critical importance of kernel-mode security in operating systems, as flaws in core system components can provide attackers with direct pathways to system compromise. Security professionals should monitor for exploitation attempts of this vulnerability through network intrusion detection systems and endpoint protection solutions, as attackers may attempt to use this vulnerability as part of broader attack campaigns. The vulnerability's persistence across multiple Windows versions highlights the need for organizations to maintain awareness of legacy systems that may continue to run unsupported operating systems, as these systems remain at risk for exploitation of known vulnerabilities. Additionally, this vulnerability underscores the necessity of maintaining up-to-date security patches and implementing defense-in-depth strategies that include application whitelisting, privilege separation, and regular security assessments to identify and remediate similar weaknesses in system components.