CVE-2012-1138 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 vectors involving the MIRP instruction in a TrueType font.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability identified as CVE-2012-1138 represents a critical security flaw within the FreeType font rendering library that affects numerous applications including Mozilla Firefox Mobile versions prior to 10.0.4. This vulnerability stems from improper handling of the MIRP (Move Indirect Relative) instruction within TrueType font files, creating a pathway for remote attackers to exploit memory corruption issues. The flaw exists in FreeType versions before 2.4.9, making it a persistent threat across multiple software implementations that rely on this font rendering engine. The vulnerability demonstrates the inherent risks associated with font processing libraries, which are frequently targeted due to their widespread use and the complex nature of font file parsing.
The technical implementation of this vulnerability involves the manipulation of the MIRP instruction within TrueType font structures, which controls how font metrics are processed during rendering. When a maliciously crafted font file is processed by affected software, the improper validation of MIRP parameters leads to invalid heap read operations that can result in memory corruption. This memory corruption occurs because the font rendering engine fails to properly bounds-check the parameters associated with the MIRP instruction, allowing attackers to manipulate memory locations beyond the intended font data structures. The vulnerability can be exploited through various attack vectors including web browsing, email attachments, and document processing, making it particularly dangerous in environments where users frequently encounter untrusted font content. The flaw maps directly to CWE-125, which describes out-of-bounds read conditions in software implementations, and represents a classic example of memory safety issues in font processing code.
The operational impact of CVE-2012-1138 extends beyond simple denial of service scenarios to potentially enable remote code execution, making it a severe threat to affected systems. When exploited successfully, the vulnerability allows attackers to execute arbitrary code on vulnerable systems with the privileges of the affected application, typically resulting in full system compromise. The attack requires minimal user interaction, often succeeding through simple web page loading or document opening operations, which makes it particularly dangerous in mobile environments where users may be less cautious about content sources. The vulnerability affects not only Firefox Mobile but also other products that utilize FreeType for font rendering, creating a widespread attack surface. According to ATT&CK framework, this vulnerability aligns with T1203 (Exploitation for Client Execution) and T1059 (Command and Scripting Interpreter) tactics, as it enables attackers to execute malicious code through client-side exploitation mechanisms.
Mitigation strategies for CVE-2012-1138 primarily focus on updating affected software to versions that include patched FreeType libraries. System administrators should prioritize updating Mozilla Firefox Mobile to version 10.0.4 or later, while also ensuring that other applications using FreeType are updated to versions containing FreeType 2.4.9 or higher. Additional protective measures include implementing strict font validation policies, disabling automatic font downloading in web browsers, and employing sandboxing techniques to limit the potential impact of successful exploitation attempts. Network-level protections such as web application firewalls and content filtering systems can help detect and block malicious font files before they reach vulnerable applications. Security monitoring should include detection of unusual font processing activities and memory access patterns that might indicate exploitation attempts. Organizations should also consider implementing principle of least privilege configurations and regular security assessments to identify and remediate similar vulnerabilities in their font processing pipelines. The vulnerability serves as a reminder of the importance of keeping font rendering libraries updated and the critical nature of proper input validation in multimedia processing components.