CVE-2012-2556 in Windows
Summary
by MITRE
The OpenType Font (OTF) driver 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, Windows 7 Gold and SP1, Windows 8, Windows Server 2012, and Windows RT allows remote attackers to execute arbitrary code via a crafted OpenType font file, aka "OpenType Font Parsing Vulnerability."
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Analysis
by VulDB Data Team • 04/20/2021
The CVE-2012-2556 vulnerability represents a critical kernel-mode buffer overflow flaw within Microsoft Windows operating systems that affects multiple versions from Windows XP through Windows 8. This vulnerability specifically targets the OpenType Font driver component, which is responsible for processing font files within the Windows kernel space. The flaw arises from insufficient bounds checking during the parsing of OpenType font files, creating a condition where maliciously crafted font data can trigger memory corruption. The vulnerability is particularly dangerous because it operates at the kernel level, meaning successful exploitation can lead to complete system compromise with the highest privileges available to the compromised process.
The technical implementation of this vulnerability stems from improper input validation within the font parsing code that handles OpenType format files. When the kernel-mode driver processes a specially crafted OTF file, it fails to properly validate the size and structure of various font table elements, leading to a buffer overflow condition. This overflow occurs in kernel memory space, which allows attackers to overwrite critical memory locations and potentially execute arbitrary code with kernel-level privileges. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, though it manifests in kernel space rather than user space applications. The attack vector requires a user to interact with a malicious font file, typically through normal system operations such as browsing directories, viewing web content, or opening email attachments that contain embedded fonts.
The operational impact of this vulnerability extends far beyond simple code execution, as it enables attackers to achieve complete system compromise without requiring user interaction beyond the initial triggering of the vulnerable font processing. Attackers can leverage this vulnerability to install persistent backdoors, escalate privileges, modify system files, and access sensitive data across all affected Windows versions. The widespread presence of this vulnerability across multiple Windows operating systems makes it particularly attractive to threat actors, as it provides broad exploitation capabilities. According to ATT&CK framework, this vulnerability maps to T1059.007 for process injection and T1068 for exploit for privilege escalation, with the potential for T1547.001 for persistence mechanisms. The vulnerability affects not just individual systems but entire enterprise networks, as it can be exploited through various attack vectors including web browsing, email attachments, and network shares.
Mitigation strategies for CVE-2012-2556 require immediate patch application from Microsoft, as the vulnerability was addressed through security updates released in the Microsoft Security Bulletin MS12-043. Organizations should prioritize deployment of these patches across all affected systems, particularly given the kernel-level nature of the exploit. Additional defensive measures include implementing strict font file filtering policies, disabling automatic font installation, and monitoring for suspicious font-related activities in system logs. Network administrators should consider implementing application whitelisting solutions to prevent execution of untrusted font files and deploy intrusion detection systems that can identify exploitation attempts. The vulnerability also highlights the importance of secure coding practices in kernel-mode drivers and demonstrates the critical need for thorough input validation and bounds checking in system-level components. Security teams should also consider implementing endpoint detection and response solutions that can monitor for kernel-level anomalies that may indicate exploitation attempts.