CVE-2012-4786 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, R2, and R2 SP1, Windows 7 Gold and SP1, Windows 8, Windows Server 2012, and Windows RT allow remote attackers to execute arbitrary code via a crafted TrueType Font (TTF) file, aka "TrueType Font Parsing Vulnerability."
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2012-4786 represents a critical kernel-mode buffer overflow flaw in Microsoft Windows operating systems that affects a wide range of platforms including Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2, Windows 7 Gold and SP1, Windows 8, Windows Server 2012, and Windows RT. This vulnerability specifically targets the TrueType font parsing functionality within the kernel-mode drivers, creating a pathway for remote code execution that can be exploited through maliciously crafted TTF files. The flaw stems from insufficient validation of font file structures during the parsing process, allowing attackers to manipulate memory layout and potentially gain system-level privileges.
The technical implementation of this vulnerability involves the exploitation of improper bounds checking within the Windows font rendering subsystem. When a Windows system processes a malicious TTF file, the kernel-mode driver responsible for handling font parsing fails to properly validate the font structure parameters, particularly the font table offsets and sizes. This deficiency creates a condition where an attacker can craft a font file with malformed table entries that cause buffer overflows when the system attempts to read and process the font data. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which directly enables attackers to overwrite adjacent memory locations and potentially redirect execution flow to malicious code. The attack surface is particularly broad since font files are commonly encountered during normal system operations, including web browsing, email attachments, and document processing.
The operational impact of CVE-2012-4786 extends far beyond simple remote code execution, as it represents a privilege escalation vector that can be leveraged to achieve complete system compromise. Attackers can exploit this vulnerability by delivering malicious TTF files through various attack vectors including email attachments, malicious websites, or compromised software downloads. The vulnerability is particularly dangerous because it operates at kernel level, meaning successful exploitation results in SYSTEM-level privileges without requiring user interaction or elevated permissions. This makes the vulnerability highly attractive to threat actors and aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation." The attack can be executed remotely without user interaction, making it particularly effective for automated exploitation campaigns and zero-day attacks.
Mitigation strategies for this vulnerability require immediate patch management and system hardening measures. Microsoft released security updates addressing this vulnerability through Windows Update and Microsoft Security Bulletin MS12-072, which should be deployed immediately across all affected systems. Organizations should implement additional protective measures including disabling automatic font installation, implementing application whitelisting policies, and monitoring for suspicious font file usage patterns. Network-based defenses can include filtering of TTF file attachments and implementing sandboxing techniques for font processing. The vulnerability highlights the importance of maintaining up-to-date security patches and demonstrates the critical nature of kernel-mode vulnerabilities in modern operating systems. Organizations should also consider implementing security awareness training to help users recognize potentially malicious font files and establish incident response procedures specifically addressing kernel-level exploits. Proper system monitoring and logging of font processing activities can help detect exploitation attempts and provide forensic evidence for security investigations.