CVE-2002-0728 in libpng
Summary
by MITRE
Buffer overflow in the progressive reader for libpng 1.2.x before 1.2.4, and 1.0.x before 1.0.14, allows attackers to cause a denial of service (crash) via a PNG data stream that has more IDAT data than indicated by the IHDR chunk.
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Analysis
by VulDB Data Team • 06/16/2019
The vulnerability identified as CVE-2002-0728 represents a critical buffer overflow condition within the progressive reader component of libpng library versions prior to 1.2.4 and 1.0.14. This flaw specifically targets the handling of PNG image data streams where the IDAT chunk contains more data than what is declared in the IHDR chunk header. The progressive reader is designed to process PNG files incrementally, allowing applications to display images before the complete file has been read. This functionality becomes dangerous when maliciously crafted PNG files exploit the discrepancy between declared and actual data sizes.
The technical implementation of this vulnerability stems from inadequate bounds checking within the libpng library's parsing logic. When the progressive reader encounters a PNG stream where the IDAT chunk size exceeds the value specified in the IHDR chunk, the library fails to properly validate the data boundaries. This mismatch causes the buffer allocated for image data to be overflowed when the reader attempts to process the excess data. The vulnerability manifests as a stack-based buffer overflow that occurs during the parsing phase, leading to memory corruption and ultimately causing the application using libpng to crash. This behavior aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation in image processing libraries.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be exploited in various contexts where PNG files are processed. Web applications, image viewers, and any software that utilizes libpng for image handling become potential targets for attackers seeking to disrupt services. The vulnerability is particularly concerning because PNG format is widely used across the internet, making it an attractive vector for exploitation. Attackers can craft malicious PNG files that will cause crashes in applications such as web browsers, image editors, or server-side image processing systems. The exploit requires minimal privileges and can be delivered through standard web traffic, making it a significant threat to web applications that process user-uploaded images. This vulnerability directly maps to ATT&CK technique T1203, which involves the use of software exploitation to cause denial of service through application crashes.
Mitigation strategies for CVE-2002-0728 primarily involve immediate patching of affected libpng versions to 1.2.4 or later for the 1.2.x series, and 1.0.14 or later for the 1.0.x series. Organizations should also implement input validation measures to verify PNG file integrity before processing, including checking that IDAT chunk sizes match the declared values in IHDR chunks. Network-level defenses such as web application firewalls can be configured to scan for suspicious PNG file patterns, while application-level protections should include proper error handling and memory management practices. The vulnerability highlights the importance of robust input validation in multimedia processing libraries and underscores the need for regular security updates in widely-used open source components. Additionally, developers should consider implementing sandboxing mechanisms for image processing operations to limit the potential impact of such vulnerabilities in production environments.