CVE-2017-11574 in FontForge
Summary
by MITRE
FontForge 20161012 is vulnerable to a heap-based buffer overflow in readcffset (parsettf.c) resulting in DoS or code execution via a crafted otf file.
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Analysis
by VulDB Data Team • 12/13/2022
The vulnerability identified as CVE-2017-11574 affects FontForge version 20161012 and represents a critical heap-based buffer overflow condition within the readcffset function located in the parsettf.c source file. This flaw manifests when the application processes specially crafted OpenType font files that contain malformed data structures. The buffer overflow occurs during the parsing of font table offsets, where insufficient input validation allows an attacker to provide data that exceeds the allocated memory buffer boundaries. The technical implementation involves the application's failure to properly bounds-check user-supplied data during font file interpretation, creating an exploitable condition that can be leveraged by malicious actors.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable remote code execution within the context of the application's privileges. When a victim opens or processes a maliciously crafted otf file through FontForge, the buffer overflow can corrupt adjacent memory regions, potentially allowing an attacker to overwrite critical program data or function pointers. This memory corruption can result in arbitrary code execution, enabling attackers to gain control over the affected system or cause application crashes that lead to denial of service conditions. The vulnerability is particularly concerning given FontForge's widespread use in font editing and creation workflows across various operating systems and platforms.
From a cybersecurity perspective, this vulnerability maps to CWE-121, heap-based buffer overflow, and aligns with multiple ATT&CK techniques including T1203, Exploitation for Client Execution, and T1059, Command and Scripting Interpreter. The attack surface is broad as FontForge is commonly used in graphic design workflows, software development environments, and font distribution systems where users might encounter malicious font files. The vulnerability demonstrates poor input validation practices and inadequate memory management within the font parsing subsystem, highlighting the importance of defensive programming techniques such as bounds checking, memory sanitization, and proper error handling. Organizations utilizing FontForge should immediately implement mitigations including input file validation, sandboxed execution environments, and application whitelisting to prevent exploitation of this critical vulnerability.
The remediation approach requires immediate patching of FontForge to version 20170731 or later, which contains the necessary fixes for the buffer overflow condition. System administrators should also implement network-based controls to block suspicious font file types and establish strict file validation policies for font processing workflows. Additionally, users should be educated about the risks of opening untrusted font files and the importance of maintaining updated software versions. Security monitoring should include detection of anomalous font file processing activities that might indicate exploitation attempts. The vulnerability underscores the critical need for regular security updates and proper code review practices in font processing libraries to prevent similar issues in other graphics and font manipulation software components.