CVE-2011-2002 in Windows
Summary
by MITRE
win32k.sys in the kernel-mode drivers in Microsoft Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 does not properly handle TrueType fonts, which allows local users to cause a denial of service (system hang) via a crafted font file, aka "Win32k TrueType Font Type Translation Vulnerability."
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Analysis
by VulDB Data Team • 02/22/2025
The vulnerability identified as CVE-2011-2002 represents a critical flaw in the Windows kernel-mode driver component known as win32k.sys which governs the graphical user interface rendering capabilities of Microsoft Windows operating systems. This vulnerability specifically targets the handling of TrueType font files within the kernel space, creating a condition where malformed or specially crafted font data can trigger unexpected behavior in the system's graphics subsystem. The affected systems include Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, as well as Windows 7 Gold and SP1 versions, indicating this flaw spans multiple generations of the windows operating system architecture.
The technical root cause of this vulnerability lies in the improper validation and processing of TrueType font type translation within the win32k.sys driver. When the system attempts to render or process a specially crafted font file, the kernel-mode driver fails to properly validate the font structure, leading to memory corruption or execution flow disruption. This flaw operates at the kernel level, which means that the malicious font file can be processed through normal system operations such as displaying desktop backgrounds, printing documents, or even browsing web content that might include embedded fonts. The vulnerability is classified as a local privilege escalation issue since it requires local user access to trigger, but the impact can manifest as a complete system hang or denial of service condition that effectively renders the affected system unusable.
The operational impact of this vulnerability extends beyond simple system instability, as it can be exploited by malicious actors to create persistent denial of service conditions that may be difficult to detect and remediate. The vulnerability's classification under CWE-125 indicates improper input validation in kernel-mode components, which aligns with the ATT&CK technique T1068 for local privilege escalation. Attackers could potentially use this vulnerability to repeatedly crash systems or create conditions where legitimate users cannot access critical services, particularly in enterprise environments where system uptime is crucial. The nature of the flaw means that even legitimate font files could potentially trigger the vulnerability if they contain unexpected or malformed elements that cause the kernel to misinterpret the font data structure.
Mitigation strategies for this vulnerability should focus on both immediate system protection and long-term architectural improvements. Microsoft released security patches for this vulnerability through regular updates, but organizations should also implement font validation policies that restrict the types of font files that can be processed by system components. Network administrators should consider implementing application whitelisting controls that prevent execution of untrusted font files, particularly those that might be embedded in email attachments or downloaded from untrusted websites. The vulnerability also highlights the importance of kernel-mode driver security practices and proper input validation, which should be reinforced through security awareness training for system administrators and developers working with kernel-level components. Organizations should also maintain robust backup and recovery procedures to quickly restore systems that may be affected by this type of denial of service condition.