CVE-2011-0666 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-2011-0666 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 Microsoft 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 drivers that handle graphics and user interface operations, specifically within the win32k.sys driver responsible for managing windowing system components. This vulnerability is categorized under CWE-416 as a use-after-free condition, where memory that has been freed is subsequently accessed, potentially leading to arbitrary code execution or privilege escalation.
The technical exploitation of this vulnerability occurs when a malicious application manipulates driver object management incorrectly, creating a scenario where a freed memory block is accessed after being deallocated. The flaw stems from improper handling of reference counting and object lifecycle management within the kernel-mode driver, allowing local attackers to craft applications that trigger the use-after-free condition. The vulnerability is particularly dangerous because it operates at kernel level, where the attacker can leverage the flaw to escalate privileges from user-level to system-level access, effectively gaining complete control over the affected system. This type of vulnerability aligns with ATT&CK technique T1068 which covers privilege escalation through kernel-mode exploits.
The operational impact of CVE-2011-0666 is severe as it enables local privilege escalation attacks that can be exploited by malicious software or determined attackers with user-level access. Once successfully exploited, the vulnerability allows attackers to execute arbitrary code with the highest privileges available on the system, potentially leading to full system compromise. The widespread affected versions mean that organizations running any of the targeted Windows operating systems are vulnerable, creating a significant attack surface. The vulnerability's classification as a "Win32k Use After Free Vulnerability" distinguishes it from other related vulnerabilities such as those mentioned in MS11-034, which addresses different types of kernel-mode flaws. Security researchers have noted that this vulnerability is particularly challenging to exploit due to the complex nature of kernel-mode memory management and the sophisticated techniques required to achieve reliable privilege escalation.
Mitigation strategies for CVE-2011-0666 primarily focus on immediate patching through Microsoft's security updates, as the vulnerability was addressed in the Microsoft Security Bulletin MS11-034. Organizations should prioritize deployment of the relevant security patches across all affected systems to eliminate the risk. Additionally, implementing security measures such as kernel-mode exploit protection, application whitelisting, and restricting user privileges can help reduce the attack surface. The vulnerability's nature makes it particularly susceptible to exploitation through social engineering or by leveraging other initial access vectors, making comprehensive security hygiene essential. System administrators should also monitor for any signs of exploitation attempts and consider implementing network segmentation to limit potential lateral movement if a system is compromised. The vulnerability's presence in multiple Windows versions underscores the importance of maintaining up-to-date security patches and following Microsoft's recommended security practices for all operating systems in use.