CVE-2012-1126 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 crafted property data in a BDF font.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 04/24/2019
The vulnerability identified as CVE-2012-1126 represents a critical heap-based buffer overflow in the FreeType font rendering library that affects multiple applications including Mozilla Firefox Mobile. This flaw resides in the BDF (Bitmap Distribution Format) font handling component of FreeType versions prior to 2.4.9, making it particularly dangerous as BDF fonts are commonly used in embedded systems and mobile environments where memory constraints are more severe. The vulnerability stems from inadequate input validation when processing property data within BDF font files, allowing attackers to craft malicious font files that trigger memory corruption during font rendering operations. The flaw operates through a classic buffer overread condition where the FreeType library attempts to read beyond allocated heap memory boundaries when parsing malformed BDF property data, creating opportunities for both denial of service and potential code execution.
The technical implementation of this vulnerability involves the FreeType library's font property parsing mechanism which fails to properly validate the length and structure of property data within BDF font files. When a malicious BDF font is processed, the library's parsing routines do not adequately check array bounds or validate input parameters, leading to heap memory corruption that can result in invalid heap read operations. This memory corruption can manifest in several ways including application crashes, memory corruption that may be exploited to execute arbitrary code, or complete denial of service conditions where the targeted application becomes unresponsive. The vulnerability is particularly concerning in mobile environments where Firefox Mobile was affected, as these platforms typically have limited memory resources and less sophisticated memory protection mechanisms compared to desktop systems. The flaw falls under CWE-125, which specifically addresses out-of-bounds read conditions, and can be mapped to ATT&CK technique T1059.007 for remote code execution through application vulnerabilities.
The operational impact of CVE-2012-1126 extends beyond simple denial of service to potentially enable remote code execution in affected systems, making it a significant threat vector for attackers targeting mobile and embedded devices. The vulnerability affects not only Firefox Mobile but also other applications that rely on FreeType for font rendering, including various Linux distributions, embedded systems, and desktop applications. Attackers can exploit this vulnerability by delivering malicious BDF font files through various attack vectors including email attachments, web downloads, or compromised websites. The memory corruption aspect of this vulnerability makes it particularly dangerous as it can be leveraged to overwrite critical memory locations, potentially allowing for privilege escalation or arbitrary code execution. In mobile environments, where users frequently download content from untrusted sources and applications have elevated privileges, this vulnerability creates a significant attack surface that can be exploited to compromise entire devices. The lack of proper bounds checking in the BDF font parser represents a fundamental flaw in the library's defensive programming practices and highlights the importance of input validation in security-critical components.
Mitigation strategies for CVE-2012-1126 primarily involve immediate patching of affected FreeType versions to 2.4.9 or later, which includes enhanced bounds checking and input validation in the BDF font handling routines. System administrators should prioritize updating Firefox Mobile to version 10.0.4 or higher, as well as ensuring that all applications utilizing FreeType are updated to versions that incorporate the patched library. Additional protective measures include implementing strict font file validation policies that reject BDF fonts from untrusted sources, deploying network-based intrusion detection systems that can identify malicious font file patterns, and configuring applications to run with minimal privileges to limit potential damage from successful exploitation attempts. Organizations should also consider implementing sandboxing mechanisms for font rendering operations and monitoring for unusual memory access patterns that may indicate exploitation attempts. The vulnerability underscores the critical importance of maintaining up-to-date font libraries and implementing comprehensive security testing practices that include fuzzing of font parsing components to identify similar buffer overflow conditions in other parts of the application stack.