CVE-2011-1240 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-2011-1240 vulnerability represents a critical use-after-free condition within the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This flaw exists in the windowing subsystem that manages graphical user interface elements including windows, menus, and other visual components. The 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, making it one of the most widespread kernel-mode vulnerabilities of its era. The vulnerability falls under CWE-416, which categorizes use-after-free flaws as a fundamental memory safety issue where freed memory is accessed, potentially leading to arbitrary code execution.
The technical exploitation of this vulnerability occurs through incorrect management of driver objects within the win32k.sys kernel driver. When a malicious application creates and manipulates window objects in a specific sequence, it can cause the kernel driver to free memory associated with a window object while still maintaining references to that memory location. This creates a scenario where subsequent operations on the freed memory can be controlled by an attacker, leading to potential privilege escalation. The vulnerability operates at the kernel level, meaning successful exploitation can result in SYSTEM-level privileges, allowing attackers to bypass standard user access controls and execute arbitrary code with the highest possible system permissions.
The operational impact of CVE-2011-1240 is severe and has been extensively documented in various threat intelligence reports. Attackers typically leverage this vulnerability through local privilege escalation exploits that require minimal user interaction, often appearing as legitimate application behavior to avoid detection by security controls. The vulnerability's presence in multiple Windows versions and service packs created a massive attack surface, with exploitation techniques being widely shared in underground forums and malware kits. Security researchers have noted that this vulnerability was frequently used in targeted attacks and advanced persistent threat campaigns due to its reliability and the high privileges it can grant. The vulnerability's classification as a different "Vulnerability Type 1" from MS11-034 demonstrates its distinct exploitation characteristics and memory management flaws.
Mitigation strategies for CVE-2011-1240 primarily focus on immediate patching of affected systems, as Microsoft released security updates through MS11-034 that addressed the underlying memory management issues in win32k.sys. Organizations should prioritize deployment of these patches across all affected Windows systems, particularly those running older service pack versions that were more vulnerable. Additionally, implementing security controls such as kernel mode exploit prevention mechanisms, application whitelisting, and restricting local user privileges can significantly reduce the risk of exploitation. Network segmentation and monitoring for suspicious windowing subsystem activity can help detect potential exploitation attempts. The vulnerability's exploitation patterns align with ATT&CK technique T1068, which covers 'Local Privilege Escalation', and T1059, 'Command and Scripting Interpreter', as attackers often combine this vulnerability with other techniques to establish persistent access. System administrators should also consider implementing endpoint detection and response solutions that can identify anomalous memory access patterns consistent with use-after-free exploitation attempts, as these tools can provide additional layers of defense against such sophisticated kernel-mode attacks.