CVE-2014-9670 in FreeType
Summary
by MITRE
Multiple integer signedness errors in the pcf_get_encodings function in pcf/pcfread.c in FreeType before 2.5.4 allow remote attackers to cause a denial of service (integer overflow, NULL pointer dereference, and application crash) via a crafted PCF file that specifies negative values for the first column and first row.
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Analysis
by VulDB Data Team • 03/08/2022
The vulnerability identified as CVE-2014-9670 represents a critical security flaw within the FreeType font rendering library, specifically affecting versions prior to 2.5.4. This issue manifests in the pcf_get_encodings function located within the pcf/pcfread.c source file, where multiple integer signedness errors create exploitable conditions that can be leveraged by remote attackers to disrupt system operations. The flaw occurs when processing Portable Compiled Format font files, which are commonly used in various operating systems and applications for font rendering. The vulnerability stems from inadequate input validation and improper handling of negative integer values in the context of font file parsing operations.
The technical implementation of this vulnerability involves integer signedness errors that occur when the pcf_get_encodings function processes font file metadata. When a maliciously crafted PCF file contains negative values for the first column and first row parameters, the function fails to properly validate these inputs before performing arithmetic operations. These signedness errors lead to integer overflow conditions where the negative values are interpreted as unsigned integers, causing unexpected behavior in memory allocation and array indexing operations. The vulnerability can result in NULL pointer dereference scenarios when the function attempts to access memory locations that have not been properly initialized or allocated. This fundamental flaw in input validation creates a chain of cascading failures that ultimately leads to application crashes and denial of service conditions.
The operational impact of CVE-2014-9670 extends beyond simple service disruption, as it represents a significant threat to system stability and availability across platforms that rely on FreeType for font rendering. Attackers can exploit this vulnerability by crafting specially formatted PCF font files that trigger the integer overflow conditions during normal font processing operations. The vulnerability affects systems where FreeType is integrated as a core component, including web browsers, office applications, graphic design software, and operating systems that utilize font rendering services. The denial of service impact can be particularly severe in environments where font rendering is critical for user interface functionality or where applications are not designed to handle unexpected crashes gracefully. This vulnerability can be exploited in various attack scenarios including web-based attacks, file attachment exploits, and supply chain compromises where malicious font files are distributed through legitimate channels.
Mitigation strategies for this vulnerability require immediate patching of affected FreeType installations to version 2.5.4 or later, which includes proper input validation and signedness handling for the affected function. System administrators should implement comprehensive font file validation mechanisms that scan for potentially malicious font files before processing them, particularly in environments where untrusted font content may be encountered. The fix addresses the underlying CWE-190 issue related to integer overflow conditions and aligns with ATT&CK technique T1059.007 for execution through font rendering processes. Organizations should also consider implementing application sandboxing and privilege separation mechanisms to limit the impact of potential exploitation, ensuring that font processing operations cannot compromise the broader system. Regular security updates and vulnerability assessments should be conducted to identify similar issues in other font rendering libraries and system components that may exhibit similar vulnerabilities in input validation and integer handling processes.