CVE-2015-7802 in OptiPNG
Summary
by MITRE
gifread.c in gif2png, as used in OptiPNG before 0.7.6, allows remote attackers to cause a denial of service (uninitialized memory read) via a crafted GIF file.
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Analysis
by VulDB Data Team • 07/26/2022
The vulnerability identified as CVE-2015-7802 represents a critical memory access flaw within the gif2png utility component of OptiPNG software versions prior to 0.7.6. This issue manifests as an uninitialized memory read condition that can be exploited by remote attackers through the careful crafting of malicious GIF image files. The vulnerability resides in the gifread.c source file, which forms a crucial part of the image processing pipeline for converting gif files to png format within the OptiPNG toolset.
The technical flaw stems from improper memory initialization within the gif2png processing logic where the application fails to properly initialize memory segments before reading data from crafted GIF files. When a maliciously constructed GIF file is processed, the software attempts to read from memory locations that have not been properly initialized, leading to unpredictable behavior and ultimately resulting in a denial of service condition. This uninitialized memory read vulnerability falls under the category of memory safety issues commonly classified as CWE-457, which specifically addresses the use of uninitialized variables in programming contexts. The vulnerability demonstrates a fundamental weakness in input validation and memory management practices within the image parsing code.
From an operational impact perspective, this vulnerability creates significant security risks for systems that rely on OptiPNG for image processing tasks, particularly in web applications or automated systems that accept user-uploaded images. Remote attackers can exploit this weakness by simply uploading a specially crafted GIF file that triggers the uninitialized memory read, causing the gif2png utility to crash or behave unpredictably. This denial of service condition can be particularly damaging in environments where image processing is critical to application functionality, as it can effectively render the service unavailable to legitimate users. The attack vector is particularly concerning because it requires minimal technical expertise to execute and can be automated, making it a popular choice for attackers seeking to disrupt services.
The mitigation strategy for CVE-2015-7802 involves upgrading to OptiPNG version 0.7.6 or later, which includes proper memory initialization routines and input validation measures that address the uninitialized memory read issue. System administrators should also implement additional protective measures such as input sanitization for image uploads, file type verification, and monitoring for unusual processing patterns that might indicate exploitation attempts. Security professionals should consider this vulnerability in the context of broader attack frameworks like those described in the MITRE ATT&CK methodology where such memory corruption vulnerabilities are categorized under the technique of "Memory Corruption" and can be leveraged as initial access vectors or for privilege escalation in more complex attack scenarios. Organizations should also implement network segmentation and access controls to limit the potential impact of such vulnerabilities within their infrastructure.