CVE-2016-10244 in FreeType
Summary
by MITRE
The parse_charstrings function in type1/t1load.c in FreeType 2 before 2.7 does not ensure that a font contains a glyph name, which allows remote attackers to cause a denial of service (heap-based buffer over-read) or possibly have unspecified other impact via a crafted file.
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Analysis
by VulDB Data Team • 12/24/2024
The vulnerability identified as CVE-2016-10244 resides within the FreeType 2 font rendering library, specifically in the parse_charstrings function located in type1/t1load.c. This critical flaw affects versions prior to 2.7 and represents a significant security concern for systems that process untrusted font files. The vulnerability stems from inadequate validation of font structure elements, particularly the absence of proper checks for glyph name existence within font files. FreeType is widely deployed across operating systems, web browsers, and applications that handle font rendering, making this vulnerability particularly dangerous as it can be exploited through various attack vectors involving malicious font files.
The technical implementation of this vulnerability involves a heap-based buffer over-read condition that occurs when the parse_charstrings function processes Type 1 font files without verifying that glyph names are present in the font structure. This flaw allows attackers to craft specially designed font files that trigger memory access violations when the library attempts to read beyond allocated buffer boundaries. The function fails to validate the integrity of font data before processing, specifically neglecting to ensure that font glyphs contain the expected name attributes. When such malformed font files are processed, the library's memory management system becomes compromised, potentially leading to application crashes, memory corruption, or in more severe cases, arbitrary code execution depending on the system's memory layout and security mitigations in place. This type of vulnerability falls under CWE-125, which specifically addresses out-of-bounds read conditions.
The operational impact of CVE-2016-10244 extends across numerous computing environments where FreeType is utilized for font processing. Attackers can exploit this vulnerability through various means including email attachments, web content, document files, or any medium that delivers font data to systems running affected FreeType versions. The vulnerability is particularly concerning in web browsers where font rendering is frequently processed, as users may inadvertently trigger the exploit through normal browsing activities. The remote nature of the attack means that exploitation can occur without user interaction, making it especially dangerous for automated attack scenarios. Additionally, the potential for unspecified other impacts suggests that beyond simple denial of service, there may be opportunities for privilege escalation or information disclosure depending on the target system configuration and the specific memory corruption patterns that result from the buffer over-read.
Mitigation strategies for this vulnerability require immediate patching of affected FreeType installations to version 2.7 or later, which includes proper validation of font structure elements and implementation of bounds checking for glyph name attributes. System administrators should prioritize updating all applications that depend on FreeType, including web browsers, office suites, and operating systems that utilize this library for font rendering. Network security controls such as email filtering and web content scanning should be enhanced to detect and block potentially malicious font files. The vulnerability demonstrates the importance of input validation and proper memory management in font processing libraries, aligning with ATT&CK technique T1203 which covers the exploitation of memory corruption vulnerabilities. Organizations should also implement monitoring for unusual application crashes or memory access patterns that could indicate exploitation attempts, while ensuring that font processing components are isolated and hardened against potential buffer overflow conditions through stack canaries, address space layout randomization, and other memory safety mechanisms.