CVE-2012-1867 in Windows
Summary
by MITRE
Integer 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 local users to gain privileges via a crafted TrueType font file that triggers incorrect memory allocation, aka "Font Resource Refcount Integer Overflow Vulnerability."
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Analysis
by VulDB Data Team • 10/17/2024
The CVE-2012-1867 vulnerability represents a critical integer overflow flaw within the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This vulnerability specifically targets the font resource reference counting mechanism that manages how TrueType font files are processed and allocated within the Windows kernel space. The flaw exists in the way the system handles memory allocation when processing crafted font files, creating a condition where an integer overflow occurs during the calculation of memory requirements for font resources. This vulnerability affects a broad range of Microsoft Windows versions including XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 variants, and Windows 7 Gold and SP1 editions, making it particularly dangerous due to its widespread impact across multiple operating system generations.
The technical exploitation of this vulnerability occurs when a local attacker crafts a specially designed TrueType font file that triggers the integer overflow condition within the win32k.sys driver. During normal font processing operations, the system calculates memory requirements for font resources based on font file parameters, but the integer overflow causes the calculation to produce a value that exceeds the maximum representable integer, resulting in unexpected memory allocation behavior. This overflow condition leads to improper memory handling where the system allocates insufficient memory for the font resource structure, potentially creating memory corruption that can be leveraged by malicious code. The vulnerability is classified as a CWE-190 Integer Overflow or Wraparound, which is a well-documented weakness in software security where arithmetic operations produce values that exceed the maximum or minimum limits of the data type being used.
From an operational perspective, this vulnerability creates a significant privilege escalation vector that allows local users to elevate their privileges from standard user level to SYSTEM level access. The attack requires local system access to execute the malicious font file, but once successful, the attacker gains complete control over the affected system. The exploitation process typically involves loading the crafted font file through normal Windows font handling mechanisms, which then triggers the overflow condition in the kernel driver. This vulnerability is particularly concerning because it operates at the kernel level where the attacker can bypass normal user-mode security controls and access system resources that would otherwise be protected. The impact extends beyond individual system compromise as it can enable further lateral movement within networks and facilitate the deployment of additional malicious tools or persistence mechanisms.
Mitigation strategies for CVE-2012-1867 focus primarily on immediate patch application through Microsoft's security updates, which address the integer overflow condition in the win32k.sys driver. Organizations should prioritize deployment of the relevant security patches as they provide direct remediation for the underlying flaw. System hardening measures include restricting font installation privileges and implementing strict file execution policies that prevent unauthorized font file execution. Network segmentation and least privilege access controls can limit the potential impact of successful exploitation by reducing the attack surface and preventing lateral movement. Monitoring for suspicious font file loading activities and anomalous memory allocation patterns can help detect exploitation attempts. Additionally, implementing application whitelisting solutions can prevent execution of unauthorized font processing code, while regular security assessments should verify that all affected systems have received proper patching. The vulnerability demonstrates the importance of kernel-mode security and highlights the critical need for robust input validation in system drivers, as this flaw could be exploited by malware or advanced persistent threats to establish persistent system compromise with elevated privileges.