CVE-2010-3855 in Apple
Summary
by MITRE
Buffer overflow in the ft_var_readpackedpoints function in truetype/ttgxvar.c in FreeType 2.4.3 and earlier allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted TrueType GX font.
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Analysis
by VulDB Data Team • 07/22/2018
The vulnerability identified as CVE-2010-3855 represents a critical buffer overflow flaw within the FreeType font rendering library version 2.4.3 and earlier. This issue resides in the ft_var_readpackedpoints function located within the truetype/ttgxvar.c file, which processes TrueType GX font variations. The flaw occurs when the library attempts to parse and handle packed points data within these specialized font formats, creating a scenario where maliciously crafted input can trigger unintended memory behavior. The vulnerability specifically targets the font processing subsystem that handles variable font data, making it particularly dangerous in environments where arbitrary font files might be processed.
The technical exploitation of this buffer overflow stems from inadequate input validation and bounds checking within the font parsing routine. When FreeType encounters a specially crafted TrueType GX font containing malformed packed points data, the ft_var_readpackedpoints function fails to properly verify array boundaries before writing data to memory buffers. This allows attackers to write beyond allocated memory regions, potentially causing application crashes or enabling more sophisticated code execution attacks. The vulnerability manifests as a classic stack-based buffer overflow that can be triggered through the normal font rendering process when applications load or display affected font files.
The operational impact of CVE-2010-3855 extends beyond simple denial of service scenarios to potentially enable remote code execution in affected systems. Applications that utilize FreeType for font rendering across operating systems including Windows, Linux, and macOS become vulnerable when processing malicious TrueType GX fonts. The attack surface includes web browsers, desktop applications, print systems, and any software that relies on FreeType for font handling. This vulnerability particularly affects systems where users might encounter untrusted font files, such as email attachments, web downloads, or shared document environments. The potential for arbitrary code execution makes this flaw especially concerning for enterprise environments where font processing occurs automatically during document rendering or application startup.
Mitigation strategies for CVE-2010-3855 should prioritize immediate software updates to FreeType versions 2.4.4 and later, which contain patches addressing the buffer overflow condition. System administrators should implement comprehensive font validation procedures, particularly for untrusted font files, and consider sandboxing font processing components to limit potential damage from successful exploits. The vulnerability aligns with CWE-121, which categorizes stack-based buffer overflow conditions, and represents a significant concern under ATT&CK framework category T1059 for execution through system services. Organizations should also consider implementing network-based protections such as intrusion detection systems that can identify malformed font data patterns and employ automated font file scanning to detect potentially malicious TrueType GX font variations before they can be processed by vulnerable applications.