CVE-2018-20588 in otfcc
Summary
by MITRE
lib/support/unicodeconv/unicodeconv.c in libotfcc.a in otfcc v0.10.3-alpha has a buffer over-read.
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Analysis
by VulDB Data Team • 06/22/2023
The vulnerability identified as CVE-2018-20588 resides within the otfcc library version 0.10.3-alpha, specifically in the unicodeconv.c file located within the lib/support/unicodeconv/ directory. This issue manifests as a buffer over-read condition that occurs during the processing of Unicode character conversions, representing a critical security flaw that can potentially lead to system compromise or information disclosure. The vulnerability is classified under CWE-125 as an out-of-bounds read, which is a common class of memory safety issues that can be exploited to gain unauthorized access to system resources or cause application crashes. The otfcc library is designed for OpenType font compilation and decompilation operations, making it a component that handles font file processing in various applications.
The technical flaw stems from improper bounds checking within the unicode conversion routines where the application reads data beyond the allocated buffer boundaries. When processing font files containing specially crafted Unicode sequences, the code fails to validate the length of input data against the buffer size, allowing an attacker to potentially read memory contents that should remain inaccessible. This over-read condition can expose sensitive data such as stack contents, heap information, or other application memory segments that may contain credentials, encryption keys, or other confidential information. The vulnerability is particularly concerning because font files are commonly encountered in user environments and can be executed through various applications without user awareness, providing an attack surface that can be exploited through social engineering or automated processing.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can be leveraged to achieve remote code execution or information disclosure depending on the target system configuration and memory layout. Attackers can craft malicious font files that trigger the buffer over-read when processed by applications using the vulnerable otfcc library, potentially leading to privilege escalation or complete system compromise. The vulnerability affects any system that utilizes otfcc v0.10.3-alpha for font processing, including web browsers, desktop applications, and server-side font conversion tools. This represents a significant risk in environments where font files are automatically processed or where users can upload font content, as it can be exploited through file upload vulnerabilities or by tricking users into opening malicious font files.
Mitigation strategies should focus on immediate patching of the affected library to version 0.10.3 or later where the buffer over-read has been addressed. Organizations should implement strict input validation for all font file processing operations and consider sandboxing font handling components to limit potential damage from exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1059.007 for execution through scripting and T1203 for exploitation of software vulnerabilities, highlighting the need for both network monitoring and application-level security controls. Additionally, implementing runtime protections such as address space layout randomization and stack canaries can help mitigate exploitation attempts, while regular security audits of font processing libraries should be conducted to identify similar memory safety issues. The vulnerability underscores the importance of proper memory management practices and the need for comprehensive testing including fuzzing to identify buffer over-read conditions in font processing libraries.