CVE-2012-1137 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 header in a BDF font.
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Analysis
by VulDB Data Team • 05/01/2018
The vulnerability identified as CVE-2012-1137 represents a critical heap memory corruption issue within the FreeType font rendering library that affects multiple software products including Mozilla Firefox Mobile. This vulnerability stems from improper handling of malformed BDF (Bitmap Distribution Format) font headers during the font parsing process. The flaw enables remote attackers to craft specially designed font files that, when processed by affected applications, trigger invalid heap read operations and subsequent memory corruption. The vulnerability specifically impacts FreeType versions prior to 2.4.9 and affects mobile browsers and applications that utilize this font rendering library for displaying text content.
The technical exploitation of this vulnerability occurs through the manipulation of BDF font headers, which contain metadata about bitmap font characteristics including dimensions, encoding, and other structural information. When FreeType processes these malformed headers without proper validation, the font parsing routine attempts to read from invalid memory locations or performs operations on corrupted heap memory segments. This improper memory management creates opportunities for attackers to either cause application crashes through denial of service conditions or potentially execute arbitrary code by carefully crafting the malicious font data to overwrite critical memory areas. The vulnerability falls under CWE-125, which describes "Out-of-bounds Read" conditions, and CWE-787, which covers "Out-of-bounds Write" scenarios that can result in memory corruption.
The operational impact of CVE-2012-1137 extends beyond simple service disruption to potentially enable remote code execution in affected systems. Mobile browsers that rely on FreeType for font rendering become particularly vulnerable since users may encounter malicious font files through various attack vectors including email attachments, web pages, or downloaded content. The vulnerability's exploitation can lead to complete system compromise when successful, as attackers can leverage the memory corruption to inject and execute malicious code within the application context. This makes the vulnerability particularly dangerous in mobile environments where users may have limited security awareness and where applications have elevated privileges for rendering content. The ATT&CK framework categorizes this vulnerability under T1059 for command and script injection, as successful exploitation could allow attackers to execute arbitrary commands on the affected system.
Mitigation strategies for this vulnerability require immediate patching of affected FreeType installations to version 2.4.9 or later, which includes proper input validation and memory boundary checks for BDF font headers. Organizations should implement comprehensive software update policies to ensure all affected applications, particularly mobile browsers and embedded systems, receive timely security patches. Additional defensive measures include implementing font file validation mechanisms that scan for malformed BDF headers before processing, deploying network-based intrusion detection systems that can identify suspicious font-related traffic patterns, and configuring application sandboxing to limit the potential impact of successful exploitation attempts. System administrators should also consider disabling support for BDF font formats in applications where this functionality is not critical, thereby reducing the attack surface for this particular vulnerability.