CVE-2016-5637 in libbpg
Summary
by MITRE
The restore_tqb_pixels function in libbpg 0.9.5 through 0.9.7 mishandles the transquant_bypass_enable_flag value, which allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds write) via a crafted BPG image, related to a "type confusion" issue.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability identified as CVE-2016-5637 resides within the libbpg library version 0.9.5 through 0.9.7, specifically within the restore_tqb_pixels function. This flaw represents a critical security issue that stems from improper handling of the transquant_bypass_enable_flag value during image processing operations. The affected library is commonly used for decoding and processing BPG (Better Portable Graphics) image format files, which are designed to provide superior compression ratios compared to traditional formats like jpeg. The vulnerability manifests when the library processes maliciously crafted BPG images that manipulate the transquant_bypass_enable_flag parameter in ways that were not anticipated during the library's development. This type of flaw falls under the category of type confusion vulnerabilities as defined by CWE-466, where the program incorrectly handles data types during processing operations. The transquant_bypass_enable_flag is a parameter used in video compression standards that controls whether certain quantization operations should be bypassed during decoding, and when improperly managed, it can lead to unpredictable behavior in memory operations.
The technical execution of this vulnerability occurs through an out-of-bounds write condition that arises when the restore_tqb_pixels function attempts to process pixel data without proper validation of the transquant_bypass_enable_flag value. When an attacker crafts a BPG image with malicious values for this flag, the function fails to properly bounds-check array accesses or validate parameter ranges, leading to memory corruption. The out-of-bounds write vulnerability is particularly dangerous because it can overwrite adjacent memory locations, potentially allowing attackers to execute arbitrary code on the target system or cause a denial of service through application crashes. This vulnerability aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where adversaries leverage software vulnerabilities to execute malicious code. The flaw essentially allows an attacker to manipulate the program's execution flow by corrupting memory structures that control pixel processing operations, making it a serious concern for any system that processes untrusted image files through the affected library.
The operational impact of CVE-2016-5637 extends beyond simple denial of service scenarios to encompass potential remote code execution capabilities that could be exploited in various attack vectors. Systems that utilize libbpg for image processing, including web applications, image editing software, and content management systems, become vulnerable to exploitation when they process BPG images from untrusted sources. The vulnerability is particularly concerning in web environments where users can upload images, as attackers could craft malicious BPG files that, when processed by vulnerable applications, would trigger the out-of-bounds write condition. The exploitability of this vulnerability is heightened because BPG files can be embedded in various web contexts, making it possible for attackers to deliver payloads through standard web browsing or file upload mechanisms. Organizations using vulnerable versions of libbpg should consider this vulnerability as a high-priority risk, particularly in environments where image processing occurs without proper input validation or sandboxing measures. The vulnerability also demonstrates the importance of proper input validation and bounds checking in multimedia processing libraries, as these components often handle complex data structures that require careful memory management to prevent exploitation.
Mitigation strategies for CVE-2016-5637 should focus on immediate remediation through version updates to libbpg 0.9.8 or later, which contain patches addressing the transquant_bypass_enable_flag handling issue. Organizations should implement comprehensive input validation for all image files processed through affected systems, including BPG format files, to prevent malformed data from reaching the vulnerable library functions. Network segmentation and application sandboxing can provide additional defense-in-depth measures by limiting the potential impact of successful exploitation attempts. Security monitoring should include detection of unusual image processing activities or memory access patterns that might indicate exploitation attempts. The vulnerability also highlights the need for regular security assessments of third-party libraries used in applications, particularly those handling multimedia content. System administrators should consider implementing automated patch management processes to ensure timely deployment of security updates. Additionally, developers should adopt secure coding practices that emphasize bounds checking, input validation, and proper error handling in multimedia processing components, aligning with security standards such as those outlined in the OWASP Top Ten and NIST guidelines for secure software development. The incident serves as a reminder of the critical importance of maintaining up-to-date software libraries and implementing robust security controls around multimedia processing operations.