CVE-2012-1129 in iOS
Summary
by MITRE
FreeType before 2.4.9, as used in Mozilla Firefox Mobile before 10.0.4 and other products, allows remote attackers to cause a denial of service (invalid heap read operation and memory corruption) or possibly execute arbitrary code via a crafted SFNT string in a Type 42 font.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability identified as CVE-2012-1129 represents a critical heap-based buffer overflow issue within the FreeType font rendering library version 2.4.8 and earlier. This flaw exists in the processing of Type 42 fonts which are a specific font format that combines PostScript and TrueType technologies. The vulnerability manifests when the FreeType library encounters a malformed SFNT (Scalable Font Number Table) string within a Type 42 font file, creating a condition where memory operations exceed allocated boundaries. The flaw stems from inadequate input validation and bounds checking during font parsing operations, specifically affecting how the library handles certain font table structures and their associated data fields.
The technical execution of this vulnerability occurs through a carefully crafted malicious font file that contains malformed SFNT string data. When a vulnerable application such as Mozilla Firefox Mobile processes this font, the FreeType library attempts to parse the invalid string data without proper boundary checks. This results in an invalid heap read operation that can lead to memory corruption, potentially allowing attackers to manipulate memory contents or cause application crashes. The vulnerability's severity is amplified by the fact that it can be triggered through web content, making it particularly dangerous in browser environments where users may unknowingly encounter malicious font files. The flaw operates at the intersection of memory safety and font processing, where improper handling of font metadata can lead to arbitrary code execution, as classified under CWE-125 for out-of-bounds read and CWE-787 for out-of-bounds write operations.
The operational impact of CVE-2012-1129 extends beyond simple denial of service to potentially enable remote code execution in affected systems. In mobile environments like Firefox Mobile, this vulnerability could allow attackers to execute malicious code on devices simply by visiting a compromised website or downloading malicious content. The vulnerability affects not only Firefox Mobile but also other applications that utilize FreeType 2.4.8 or earlier versions for font rendering, including various operating systems and software platforms that depend on this library for displaying text and graphics. The attack vector is particularly concerning because it requires no user interaction beyond normal browsing or content consumption, making it an ideal candidate for drive-by download attacks and zero-day exploitation. This vulnerability demonstrates how font processing libraries can serve as attack surfaces for sophisticated exploitation techniques, particularly when they handle untrusted input without proper sanitization.
Mitigation strategies for CVE-2012-1129 focus primarily on updating to patched versions of FreeType library, specifically version 2.4.9 or later, where the vulnerability has been addressed through improved input validation and bounds checking mechanisms. Organizations should immediately upgrade all affected systems, including browsers, mobile applications, and any software platforms that utilize FreeType for font rendering. Additionally, implementing web content filtering and sandboxing measures can provide defense-in-depth protection against exploitation attempts. Security configurations should include disabling font embedding where possible and implementing strict input validation for all font-related content. The vulnerability highlights the importance of maintaining up-to-date font libraries and implementing proper software supply chain security practices. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and remote code execution through software exploitation, specifically targeting the application layer and system libraries. Organizations should also consider implementing network monitoring to detect potential exploitation attempts and ensure comprehensive patch management processes are in place to prevent similar vulnerabilities from affecting their environments.