CVE-2016-5735 in pngquant
Summary
by MITRE
Integer overflow in the rwpng_read_image24_libpng function in rwpng.c in pngquant 2.7.0 allows remote attackers to have unspecified impact via a crafted PNG file, which triggers a buffer overflow.
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Analysis
by VulDB Data Team • 12/07/2022
The vulnerability identified as CVE-2016-5735 represents a critical integer overflow flaw within the pngquant 2.7.0 image processing library that affects the rwpng_read_image24_libpng function in the rwpng.c source file. This vulnerability arises from inadequate input validation when processing specially crafted png files, creating a scenario where an attacker can manipulate the integer arithmetic to cause memory corruption during image decompression operations. The flaw specifically manifests when the software attempts to calculate buffer sizes based on image dimensions provided in the malicious png file, leading to an overflow condition that can result in arbitrary code execution or denial of service. The vulnerability demonstrates characteristics consistent with CWE-190, Integer Overflow or Wraparound, which is a well-documented weakness in software systems where integer arithmetic operations produce results that exceed the maximum value representable by the data type, creating opportunities for memory corruption and potential exploitation.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it provides remote attackers with the capability to execute arbitrary code on systems processing affected png files. When a vulnerable application processes the crafted png file, the integer overflow in the rwpng_read_image24_libpng function causes the program to allocate insufficient memory buffers, leading to buffer overflow conditions that can be exploited through various attack vectors including web applications, email clients, or any software that utilizes the affected pngquant library for image processing. The unspecified impact mentioned in the vulnerability description indicates that the consequences can range from system crashes and application instability to full remote code execution, depending on the specific implementation and execution environment. This vulnerability aligns with ATT&CK technique T1203, Exploitation for Client Execution, where attackers leverage vulnerabilities in image processing libraries to gain unauthorized access to systems through crafted media files.
Systems utilizing pngquant 2.7.0 or earlier versions across web applications, image processing services, or any environment where untrusted png files are processed are at risk of exploitation. The vulnerability affects not only direct applications using the library but also indirect consumers who rely on pngquant for image optimization and processing tasks. Security professionals should consider this vulnerability as part of a broader attack surface analysis, particularly in environments where file upload capabilities exist and proper input sanitization is not implemented. The integer overflow condition specifically occurs when the software calculates memory requirements for image data processing without proper bounds checking, making it susceptible to malicious input that can cause the arithmetic to wrap around and produce negative or excessively large values. This flaw demonstrates the importance of implementing robust input validation and integer overflow protection mechanisms in image processing libraries, as highlighted by industry best practices for secure coding and the principles outlined in the CWE database.
Mitigation strategies for CVE-2016-5735 should focus on immediate version updates to pngquant 2.8.0 or later, which contain fixes addressing the integer overflow vulnerability. Organizations should also implement comprehensive input validation measures for all image file processing, including size limitations, format verification, and memory allocation bounds checking. Network-level defenses such as content filtering and web application firewalls can provide additional protection by blocking suspicious image files before they reach vulnerable applications. Security teams should conduct thorough vulnerability assessments of all systems utilizing pngquant or similar image processing libraries, ensuring that proper patch management procedures are in place to prevent exploitation. The fix implemented in newer versions typically involves adding proper integer overflow checks and bounds validation before memory allocation operations, preventing the buffer overflow conditions that could be exploited by remote attackers. This vulnerability serves as a reminder of the critical importance of maintaining up-to-date software libraries and implementing proper security controls in image processing workflows to prevent exploitation of integer overflow vulnerabilities in multimedia processing applications.