CVE-2013-3894 in Windows
Summary
by MITRE
The kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows Server 2012, and Windows RT allow remote attackers to execute arbitrary code via a crafted CMAP table in a TrueType font (TTF) file, aka "TrueType Font CMAP Table Vulnerability."
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Analysis
by VulDB Data Team • 01/17/2025
The vulnerability identified as CVE-2013-3894 represents a critical kernel-mode memory corruption flaw in Microsoft Windows operating systems that affects multiple versions from Windows XP through Windows 8. This vulnerability specifically targets the handling of CMAP tables within TrueType font files, which are commonly used for text rendering across the Windows ecosystem. The flaw exists in the kernel-mode drivers responsible for processing font data, making it particularly dangerous as it operates at the highest privilege level of the operating system. Attackers can exploit this vulnerability by crafting malicious CMAP tables within specially designed TrueType font files, which when processed by the vulnerable system can lead to arbitrary code execution with kernel-level privileges.
The technical nature of this vulnerability stems from improper validation of CMAP table structures within TrueType font files during the font rendering process. When a Windows system processes a maliciously crafted TTF file containing an oversized or malformed CMAP table, the kernel-mode driver fails to properly bounds-check the data structure, leading to memory corruption that can be exploited to gain control over the system. This flaw aligns with CWE-121, which describes heap-based buffer overflow conditions, and specifically represents a classic case of improper input validation in kernel-mode components. The vulnerability is particularly insidious because it can be triggered through various attack vectors including email attachments, web downloads, or network shares, making it highly accessible to remote attackers. The attack chain typically involves the victim opening or previewing a malicious font file, which then triggers the vulnerable kernel driver to process the malformed CMAP table and execute attacker-controlled code.
The operational impact of CVE-2013-3894 is severe and far-reaching across the affected Windows platform ecosystem. Since the vulnerability operates at kernel level, successful exploitation results in complete system compromise without requiring user interaction beyond the initial triggering of the vulnerable font processing functionality. This makes it particularly dangerous for enterprise environments where users may inadvertently encounter malicious font files through various attack vectors including phishing campaigns, compromised websites, or malicious file sharing. The vulnerability affects all supported versions of Windows from XP SP2 through Windows 8, representing a massive attack surface that spans nearly a decade of operating system releases. Organizations running these vulnerable systems face significant risk of persistent malware installation, data exfiltration, and lateral movement within their networks, as attackers can leverage the kernel-level privileges to establish backdoors, disable security features, or escalate privileges to SYSTEM level access. The vulnerability also impacts Windows Server environments, making it particularly concerning for server administrators who may not have immediate access to patch management systems.
Mitigation strategies for CVE-2013-3894 must address both immediate protection and long-term remediation approaches to secure affected systems. Microsoft released security patches for this vulnerability through the regular monthly patch Tuesday updates, but organizations should prioritize immediate deployment of these patches across all affected systems. In environments where patching cannot be immediately deployed, administrators can implement several protective measures including disabling font rendering for untrusted content, implementing application whitelisting policies to prevent execution of potentially malicious font files, and configuring network security controls to block suspicious font file types. The ATT&CK framework categorizes this vulnerability under T1068, which describes Exploitation for Privilege Escalation, highlighting the need for layered security approaches that include network segmentation, endpoint protection, and user education. Additional protective measures include implementing strict file type validation for font files, monitoring for unusual font processing activity, and maintaining current antivirus signatures that specifically detect malicious font files. Organizations should also consider implementing security awareness training to help users recognize potentially malicious font files, particularly those encountered in email attachments or downloaded from untrusted sources. Regular vulnerability assessments and penetration testing should be conducted to identify systems that may still be running vulnerable versions of Windows, as the widespread nature of this vulnerability means that even small segments of an organization's infrastructure could be compromised.