CVE-2014-9667 in FreeType
Summary
by MITRE
sfnt/ttload.c in FreeType before 2.5.4 proceeds with offset+length calculations without restricting the values, which allows remote attackers to cause a denial of service (integer overflow and out-of-bounds read) or possibly have unspecified other impact via a crafted SFNT table.
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Analysis
by VulDB Data Team • 03/08/2022
The vulnerability identified as CVE-2014-9667 affects the FreeType font rendering library version 2.5.3 and earlier, specifically within the sfnt/ttload.c component responsible for processing SFNT (Simple Font Table) font structures. This flaw represents a critical security issue that demonstrates poor input validation and arithmetic handling in font parsing operations. The vulnerability occurs when the library processes font tables without proper bounds checking on offset and length calculations, creating opportunities for malicious input to trigger unexpected behavior in the font rendering process. The issue stems from the library's failure to validate the mathematical operations used to determine memory access boundaries during font table processing, which directly relates to CWE-190, Integer Overflow or Wraparound, and CWE-129, Improper Validation of Array Index.
When a maliciously crafted SFNT font table is processed by the vulnerable FreeType library, the absence of proper bounds checking allows attackers to manipulate offset and length values in ways that result in integer overflow conditions. These overflow conditions can lead to out-of-bounds memory reads where the library attempts to access memory locations beyond the allocated buffer boundaries. The vulnerability manifests as a denial of service condition when the library crashes due to invalid memory access, but it could potentially be exploited further to achieve arbitrary code execution depending on the specific memory layout and the environment in which FreeType operates. The impact extends beyond simple service disruption as this type of vulnerability can be leveraged in broader exploitation scenarios, particularly in environments where font rendering is used as part of document processing or web browsing.
The operational impact of CVE-2014-9667 is significant across multiple attack vectors since FreeType is widely used across operating systems, web browsers, and applications for font rendering. Attackers can exploit this vulnerability by delivering malicious font files through various delivery mechanisms including email attachments, web pages, or document files that trigger font rendering. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript and T1203 for Exploitation for Client Execution, as the exploitation involves manipulating font rendering processes to achieve code execution or denial of service. The vulnerability affects systems where FreeType is integrated into applications, particularly those that handle untrusted font content, including web browsers, document viewers, and graphic applications. The integer overflow and out-of-bounds read conditions can be particularly dangerous in server environments where font processing might occur during document conversion or web content rendering.
Mitigation strategies for CVE-2014-9667 require immediate patching of FreeType libraries to version 2.5.4 or later, which implements proper bounds checking and arithmetic validation for offset and length calculations. System administrators should also implement application whitelisting and sandboxing measures to limit the impact of potential exploitation attempts. Input validation should be enhanced at multiple layers including font file validation, buffer size checking, and memory access boundary enforcement. The fix addresses the root cause by implementing proper integer overflow detection and ensuring that all offset and length calculations are validated against maximum buffer sizes before proceeding with memory operations. Additionally, organizations should conduct security audits of systems using FreeType to identify and remediate potential exposure points, particularly in web-facing applications and document processing systems that may be vulnerable to this class of exploitation through font rendering components.