CVE-2011-1877 in Windows
Summary
by MITRE
Use-after-free vulnerability in win32k.sys in the kernel-mode drivers in Microsoft 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, aka "Win32k Use After Free Vulnerability."
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Analysis
by VulDB Data Team • 11/14/2021
The CVE-2011-1877 vulnerability represents a critical use-after-free condition in the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This flaw exists within the windowing subsystem that manages graphical user interface elements and handles user input processing. The vulnerability specifically manifests in Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, R2, and R2 SP1, as well as Windows 7 Gold and SP1 versions, making it a widespread issue affecting multiple Windows generations. The vulnerability is categorized under CWE-416 as a use-after-free condition, which occurs when a program continues to reference memory after it has been freed, creating opportunities for malicious code execution.
The technical exploitation of this vulnerability stems from improper management of driver objects within the win32k.sys kernel driver. When a malicious application creates and manipulates window objects, it can trigger a race condition or improper memory deallocation sequence that leads to a use-after-free scenario. This occurs during the handling of user interface events where kernel-mode code processes window messages and manages graphical resources. Attackers can craft specific applications that abuse this behavior to cause the kernel to execute arbitrary code with elevated privileges, effectively bypassing user-mode restrictions and gaining system-level access. The vulnerability leverages the kernel-mode execution context to escalate privileges from user-level to kernel-level, representing a fundamental breach in Windows security boundaries.
The operational impact of this vulnerability is severe as it allows local attackers to achieve privilege escalation without requiring network access or complex exploitation techniques. Once exploited, the vulnerability provides attackers with complete system control, enabling them to install malicious software, modify system files, access sensitive data, or establish persistent backdoors. The attack vector requires only local system access, making it particularly dangerous in environments where users may have legitimate access to systems but could be compromised or where privilege escalation is needed to perform malicious activities. This vulnerability aligns with ATT&CK technique T1068 which describes local privilege escalation and T1543 which covers creating or modifying system processes, both of which can be achieved through this kernel-level exploitation.
Mitigation strategies for CVE-2011-1877 primarily involve applying the official Microsoft security patches released in May 2011 as part of the security update bulletin MS11-046. Organizations should prioritize immediate deployment of these patches across all affected Windows systems, particularly those running the vulnerable Windows versions mentioned in the vulnerability description. System administrators should also implement additional security measures including disabling unnecessary user privileges, implementing application whitelisting policies, and monitoring for suspicious process behavior that might indicate exploitation attempts. The vulnerability demonstrates the importance of kernel-mode security and highlights why maintaining up-to-date system patches is crucial for protecting against zero-day exploits. Regular security assessments and vulnerability scanning should be conducted to identify systems that may not have received the necessary patches, as this vulnerability has been widely exploited in the wild and represents a significant risk to unpatched systems.