CVE-2011-2004 in Windows
Summary
by MITRE
Array index error in win32k.sys in the kernel-mode drivers in Microsoft Windows Server 2008 R2 and R2 SP1 and Windows 7 Gold and SP1 allows remote attackers to cause a denial of service (reboot) via a crafted TrueType font file, aka "TrueType Font Parsing Vulnerability," a different vulnerability than CVE-2011-3402.
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability identified as CVE-2011-2004 represents a critical array index error within the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This flaw specifically affects Windows Server 2008 R2 and its SP1 variant, as well as Windows 7 in both its original release and SP1 configurations. The vulnerability stems from improper validation of array indices during the processing of TrueType font files, creating a condition where maliciously crafted font data can trigger unexpected behavior in the kernel execution context. The vulnerability is classified under CWE-129 as an insufficient bounds checking, which directly relates to improper input validation and memory access control issues. This represents a classic example of a buffer over-read condition that can be exploited in kernel-mode environments, where the consequences extend beyond simple application crashes to system-wide instability.
The technical exploitation of this vulnerability occurs when a Windows system processes a specially crafted TrueType font file that contains malformed array index values. During the font parsing operation, the win32k.sys driver fails to properly validate array boundaries, allowing an attacker to manipulate memory access patterns that ultimately result in system instability. The kernel-mode nature of the vulnerability means that exploitation does not require user privileges, as the system automatically processes font files during normal operations such as displaying web content, opening email attachments, or browsing file systems. This characteristic places the vulnerability in the ATT&CK framework under the T1059.007 technique for Windows Subsystem for Linux, though more accurately it maps to T1068 for locally executed commands and T1547.001 for registry run keys, as the vulnerability enables arbitrary code execution in kernel context. The flaw specifically affects the GDI (Graphics Device Interface) subsystem which handles font rendering, making it particularly dangerous as font processing occurs across numerous system functions and applications.
The operational impact of CVE-2011-2004 manifests as a denial of service condition that can result in system reboot or complete system crash. Attackers can construct malicious TrueType font files that, when processed by the affected Windows systems, trigger the array index error and cause the kernel to become unstable. This instability can lead to system hangs, blue screen of death errors, or forced reboots, effectively rendering the affected systems unavailable to users. The vulnerability is particularly concerning because it can be triggered remotely through web browsing or email attachments, making it a prime candidate for drive-by download attacks. From a security perspective, this vulnerability represents a significant risk to enterprise environments where Windows systems are exposed to untrusted content, as the potential for denial of service attacks can be used to disrupt business operations or as part of larger attack campaigns. The vulnerability affects both server and desktop operating systems, amplifying its potential impact across network environments.
Mitigation strategies for CVE-2011-2004 should focus on both immediate remediation and long-term defensive measures. Microsoft released security update MS11-065 to address this vulnerability, which should be deployed immediately across all affected systems. Organizations should implement application whitelisting policies that prevent execution of untrusted font files, particularly those that might be encountered in email attachments or web downloads. Network-based defenses such as web proxies and email filtering systems should be configured to scan and block suspicious font file types. System administrators should consider disabling font caching or implementing additional validation layers for font processing within applications. The vulnerability highlights the importance of kernel-mode vulnerability management and the need for regular security updates. From a defensive standpoint, organizations should monitor for exploitation attempts through network traffic analysis and system logs, particularly looking for unusual font processing activity or system reboots. The vulnerability also underscores the necessity of maintaining current security patches and implementing comprehensive endpoint protection solutions that can detect and prevent exploitation attempts before they succeed. Regular security assessments should include evaluation of kernel-mode driver vulnerabilities and their potential impact on system stability and availability.