CVE-2011-1235 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-2011-1235 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 management system where improper handling of driver objects creates conditions that allow malicious code to exploit the vulnerability. The vulnerability is classified under CWE-416 as a use-after-free condition, which occurs when a program continues to use a pointer after the memory it points to has been freed, leading to potential arbitrary code execution. This specific vulnerability operates at the kernel level, making it particularly dangerous as it can escalate privileges from user-level to system-level access.
The technical exploitation of this vulnerability requires a local attacker to craft a malicious application that can manipulate the win32k.sys driver object management. The flaw manifests when the kernel-mode driver fails to properly validate or manage references to driver objects, creating a scenario where freed memory can be accessed and manipulated by an attacker. This particular vulnerability differs from other "Vulnerability Type 1" CVEs referenced in MS11-034, indicating it follows a distinct exploitation pattern that leverages the specific object management mechanisms within the win32k.sys driver. The attack vector is local, meaning an attacker must already have user-level access to the system to exploit this vulnerability, but the successful exploitation results in privilege escalation to kernel mode. The vulnerability operates within the Windows graphical subsystem, specifically targeting the windowing system components that handle user interface elements and graphics operations.
The operational impact of CVE-2011-1235 is severe as it provides local attackers with a pathway to achieve system-level compromise without requiring network access or external exploitation vectors. Once successfully exploited, the vulnerability allows attackers to execute arbitrary code with the highest privileges available on the system, effectively granting complete control over the affected machine. This privilege escalation capability means that an attacker who has already gained user-level access to a system can leverage this vulnerability to bypass security controls and gain unauthorized access to sensitive system resources. The vulnerability's presence in multiple Windows versions from XP through Windows 7 makes it particularly concerning for organizations with legacy systems, as it provides a consistent attack vector across a wide range of operating systems. The impact extends beyond individual system compromise to potentially enable broader network infiltration when combined with other exploitation techniques.
Mitigation strategies for CVE-2011-1235 primarily involve applying the Microsoft security update released as part of MS11-034, which addresses the underlying use-after-free condition in the win32k.sys driver. Organizations should prioritize patching all affected systems, particularly those running older Windows versions where the vulnerability remains unpatched. Additional defensive measures include implementing application whitelisting policies to prevent unauthorized applications from running, enabling kernel-mode exploit protection mechanisms, and conducting regular security assessments to identify systems running vulnerable versions of Windows. Network segmentation and privilege separation can help limit the potential impact of successful exploitation attempts, while monitoring for suspicious process behavior and memory access patterns can aid in early detection of exploitation attempts. The vulnerability's classification under the ATT&CK framework as a privilege escalation technique emphasizes the importance of maintaining least-privilege access controls and regular system hardening practices to reduce the attack surface and limit potential damage from successful exploitation attempts.