CVE-2017-17669 in Exiv2
Summary
by MITRE
There is a heap-based buffer over-read in the Exiv2::Internal::PngChunk::keyTXTChunk function of pngchunk_int.cpp in Exiv2 0.26. A crafted PNG file will lead to a remote denial of service attack.
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Analysis
by VulDB Data Team • 01/18/2023
The vulnerability identified as CVE-2017-17669 represents a critical heap-based buffer over-read flaw within the Exiv2 image processing library version 0.26. This issue resides in the Exiv2::Internal::PngChunk::keyTXTChunk function located in the pngchunk_int.cpp source file, demonstrating a classic memory safety vulnerability that can be exploited through maliciously crafted media files. The flaw specifically manifests when processing PNG image files that contain specially constructed data within their text chunk structures, creating a scenario where the application attempts to read memory beyond the allocated buffer boundaries.
The technical exploitation of this vulnerability occurs through a carefully crafted PNG file that triggers the buffer over-read condition during the parsing of PNG text chunks. When the Exiv2 library processes such malformed input, it fails to properly validate the length and structure of the text data within the PNG file, leading to memory access violations that can result in application crashes or unpredictable behavior. This type of vulnerability falls under the CWE-125 vulnerability category, which specifically addresses out-of-bounds read conditions in software implementations, and aligns with ATT&CK technique T1203 for legitimate program execution and T1059 for command and scripting interpreter usage in exploitation scenarios.
The operational impact of this vulnerability extends beyond simple denial of service, as it creates opportunities for remote attackers to disrupt services that rely on Exiv2 for image processing. Systems that process user-uploaded PNG files, including web applications, content management systems, and media processing platforms, become susceptible to this attack vector. The vulnerability can be particularly dangerous in environments where automated image processing workflows exist, as a single malicious file could cause cascading failures across multiple service components. The remote nature of the attack means that threat actors can exploit this vulnerability without requiring local system access, making it especially concerning for publicly accessible applications.
Mitigation strategies for CVE-2017-17669 should prioritize immediate patching of affected Exiv2 installations to version 0.27 or later, which contains the necessary fixes for the buffer over-read condition. Organizations should also implement defensive measures including input validation and sanitization of image files before processing, employing sandboxed environments for image handling, and deploying intrusion detection systems that can identify suspicious file processing patterns. Additionally, regular security assessments of image processing pipelines and comprehensive monitoring of application behavior can help detect exploitation attempts. The vulnerability demonstrates the importance of robust input validation in multimedia processing libraries and highlights the need for continuous security testing of third-party components used in critical applications, particularly those handling untrusted user data through file format parsers.