CVE-2011-1238 in Windows
Summary
by MITRE
Use-after-free vulnerability in 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 leverages incorrect driver object management, a different vulnerability than other "Vulnerability Type 1" CVEs listed in MS11-034, aka "Win32k Use After Free Vulnerability."
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Analysis
by VulDB Data Team • 03/22/2025
The CVE-2011-1238 vulnerability represents a critical use-after-free flaw in the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This vulnerability specifically affects 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 resides in the kernel-mode driver responsible for managing user interface components and graphics operations, making it a prime target for privilege escalation attacks. The vulnerability stems from improper management of driver objects within the win32k.sys module, which creates conditions where freed memory locations can be accessed and potentially exploited by malicious code.
The technical implementation of this vulnerability involves a race condition or improper memory management within the kernel-mode driver that handles user interface operations. When a legitimate application interacts with the win32k.sys driver through specific graphics or user interface calls, the driver fails to properly validate or manage object references, leading to a situation where memory that has been freed is still accessible and potentially writable. This use-after-free condition allows attackers to manipulate the freed memory location and execute arbitrary code with kernel-level privileges. The vulnerability operates at the kernel level, bypassing typical user-mode security controls and making it particularly dangerous for system compromise.
From an operational perspective, this vulnerability enables local users to escalate their privileges from standard user level to SYSTEM level execution, providing complete control over the affected system. Attackers can leverage this flaw by crafting malicious applications that trigger the vulnerable code path in win32k.sys, causing the driver to free memory that is subsequently accessed by the attacker's code. The impact extends beyond individual systems to potentially compromise entire networks if exploited in conjunction with other attack vectors or if the compromised system serves as a foothold for further lateral movement. This vulnerability was particularly significant as it affected multiple versions of Windows, creating widespread exposure across enterprise environments and making it a high-priority target for exploit development.
The mitigation strategies for CVE-2011-1238 primarily involve applying Microsoft security updates and patches that address the underlying memory management issues in the win32k.sys driver. Organizations should prioritize patching all affected systems and implement additional security controls such as kernel-mode driver validation, application whitelisting, and enhanced monitoring of system calls related to graphics and user interface operations. The vulnerability aligns with CWE-416, which describes the use of freed memory conditions, and represents a classic example of how improper resource management in kernel-mode code can lead to privilege escalation. Security professionals should also consider implementing the ATT&CK framework's privilege escalation techniques and ensure that systems are configured to minimize the attack surface through proper access controls and security hardening measures.