CVE-2011-2003 in Windows
Summary
by MITRE
Buffer overflow in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 allows remote attackers to execute arbitrary code via a crafted .fon file, aka "Font Library File Buffer Overrun Vulnerability."
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Analysis
by VulDB Data Team • 03/16/2025
The vulnerability described in CVE-2011-2003 represents a critical buffer overflow condition within the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This flaw specifically affects the font library handling functionality where the system processes .fon font files, creating a scenario where maliciously crafted font files can trigger memory corruption during kernel-level operations. The vulnerability exists in multiple Windows versions including XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2, and Windows 7 Gold and SP1, indicating a widespread impact across the Windows ecosystem. The flaw stems from insufficient bounds checking when processing font library files, allowing attackers to overflow buffers in kernel memory space.
The technical exploitation of this vulnerability occurs when a Windows system processes a specially crafted .fon file that contains malformed data structures designed to exceed the allocated buffer space in the win32k.sys driver. This buffer overflow can be triggered through various attack vectors including email attachments, web downloads, or network shares where the system automatically processes font files. The kernel-mode nature of the vulnerability means that successful exploitation results in privilege escalation from user-level to kernel-level execution, providing attackers with complete system compromise. This type of vulnerability directly maps to CWE-121, which describes heap-based buffer overflow conditions, and specifically aligns with CWE-125, representing out-of-bounds read conditions that can lead to memory corruption.
The operational impact of CVE-2011-2003 is severe as it enables remote code execution without requiring user interaction, making it particularly dangerous for enterprise environments. Attackers can leverage this vulnerability to install malware, establish backdoors, or perform data exfiltration from compromised systems. The vulnerability's presence in widely deployed Windows versions means that organizations with legacy systems or those not promptly patched face significant exposure. From an attack framework perspective, this vulnerability would typically be classified under the ATT&CK technique T1059.007 for command and scripting interpreter, and potentially T1068 for exploit for privilege escalation, as attackers can leverage the kernel-level access to execute arbitrary code with system privileges. The vulnerability's exploitation requires minimal user interaction, making it particularly dangerous for targeted attacks.
Mitigation strategies for this vulnerability involve immediate patching of affected systems through Microsoft's security updates, as the primary solution. Organizations should ensure comprehensive patch management processes are in place to address such kernel-level vulnerabilities promptly. Additional mitigations include implementing application whitelisting policies to prevent execution of untrusted font files, network segmentation to limit exposure, and monitoring for suspicious font file processing activities. The vulnerability's nature as a kernel-mode buffer overflow also necessitates enhanced memory protection mechanisms and regular security assessments of system components. Security teams should also consider implementing intrusion detection systems that can identify potential exploitation attempts targeting this specific vulnerability, as well as maintaining detailed logs of font file processing activities for forensic analysis purposes.