CVE-2011-1242 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 • 11/02/2021
The CVE-2011-1242 vulnerability represents a critical use-after-free flaw in the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This vulnerability affects a wide range of Windows versions 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 resides in the kernel-mode driver object management within the Windows graphics subsystem, specifically in how the win32k.sys driver handles reference counting and memory deallocation for kernel objects. The vulnerability is classified under CWE-416 as a Use After Free condition, where a program continues to reference memory after it has been freed, leading to potential memory corruption and arbitrary code execution.
The technical exploitation of this vulnerability occurs when a malicious application manipulates the kernel-mode driver's object management routines to trigger a use-after-free condition. Attackers can craft applications that create and manipulate graphics objects in such a way that when the win32k.sys driver processes these objects, it attempts to access memory that has already been freed and potentially reallocated. This memory corruption can be leveraged to execute arbitrary code with kernel-level privileges, effectively allowing local users to escalate their privileges from standard user level to SYSTEM level access. The vulnerability differs from other "Vulnerability Type 1" CVEs referenced in MS11-034 due to its specific implementation in the win32k.sys driver rather than other kernel components, making it particularly dangerous as it operates within the graphics subsystem which is frequently accessed by user applications.
The operational impact of this vulnerability is severe and multifaceted. Local attackers with standard user privileges can exploit this flaw to achieve privilege escalation, gaining SYSTEM-level access that would otherwise require administrative credentials or more sophisticated attack vectors. Once escalated, attackers can perform actions such as installing malware, modifying system files, creating new user accounts, disabling security features, and accessing sensitive data across the entire system. The vulnerability affects the fundamental security model of Windows operating systems by undermining the kernel-mode protection mechanisms that are designed to prevent user-mode applications from executing privileged operations. This makes the exploitation particularly attractive for attackers seeking persistent access to compromised systems, as the elevated privileges allow for complete system compromise and data exfiltration.
Mitigation strategies for CVE-2011-1242 primarily focus on applying the Microsoft security update released as part of MS11-034, which addresses the specific use-after-free condition in win32k.sys. System administrators should prioritize patching all affected Windows systems, particularly those running older versions such as Windows XP and Windows Server 2003 that are no longer receiving extended support. Additional protective measures include implementing application whitelisting policies to prevent unauthorized applications from executing, disabling unnecessary graphics services, and monitoring for suspicious kernel-mode activity that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" and T1059 which covers "Command and Scripting Interpreter" as attackers often leverage privilege escalation to establish persistent access and execute further malicious activities. Organizations should also consider implementing endpoint detection and response solutions that can identify anomalous behavior patterns associated with kernel-mode exploitation attempts, as traditional antivirus solutions may not detect such low-level vulnerabilities effectively.