CVE-2014-9674 in FreeType
Summary
by MITRE
The Mac_Read_POST_Resource function in base/ftobjs.c in FreeType before 2.5.4 proceeds with adding to length values without validating the original values, which allows remote attackers to cause a denial of service (integer overflow and heap-based buffer overflow) or possibly have unspecified other impact via a crafted Mac font.
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Analysis
by VulDB Data Team • 03/09/2022
The vulnerability identified as CVE-2014-9674 resides within the FreeType font rendering library, specifically in the Mac_Read_POST_Resource function located in base/ftobjs.c. This critical flaw affects FreeType versions prior to 2.5.4 and represents a classic integer overflow vulnerability that can be exploited remotely to cause denial of service or potentially more severe consequences. The vulnerability manifests when the function processes Mac font resources without proper validation of length parameters, creating conditions where maliciously crafted font files can trigger unexpected behavior in the font processing pipeline.
The technical implementation of this vulnerability stems from inadequate input validation within the font resource parsing logic. When FreeType encounters a Mac font file, it attempts to read the POST resource section which contains information about the font's glyph data. The Mac_Read_POST_Resource function fails to validate the length values extracted from this section before using them in subsequent memory allocation or buffer operations. This lack of validation allows attackers to craft font files with deliberately corrupted length fields that, when processed, result in integer overflow conditions. The overflow occurs when the computed length values exceed the maximum representable value for the integer type used in the calculation, leading to unexpected behavior in memory management.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more sophisticated attacks. When integer overflow occurs during buffer allocation, it can result in heap-based buffer overflows that may allow attackers to manipulate memory layout or potentially execute arbitrary code. The vulnerability affects systems that process Mac font files through FreeType, including web browsers, desktop applications, and operating systems that rely on this library for font rendering. Attackers can leverage this vulnerability by delivering maliciously crafted font files through various attack vectors such as email attachments, web pages, or downloadable content, making it particularly dangerous in environments where users frequently encounter untrusted font resources.
From a cybersecurity perspective, this vulnerability aligns with CWE-190, which describes integer overflow conditions, and demonstrates the importance of proper input validation in security-critical code sections. The ATT&CK framework categorizes this as a vulnerability exploitation technique that can be used for privilege escalation or persistent access, particularly when combined with other attack vectors. The vulnerability's remote exploitability makes it especially concerning for web-based environments where font files are commonly served and rendered automatically. Organizations using FreeType in their applications should prioritize immediate patching to address this vulnerability, as the potential for remote code execution through heap corruption makes it a high-severity threat. The remediation strategy involves updating to FreeType version 2.5.4 or later, where proper input validation has been implemented to prevent the overflow conditions that enable this attack.