CVE-2018-17230 in Exiv2
Summary
by MITRE
Exiv2::ul2Data in types.cpp in Exiv2 v0.26 allows remote attackers to cause a denial of service (heap-based buffer overflow) via a crafted image file.
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Analysis
by VulDB Data Team • 05/17/2023
The vulnerability identified as CVE-2018-17230 represents a critical heap-based buffer overflow flaw within the Exiv2 image processing library version 0.26. This issue resides in the Exiv2::ul2Data function located in the types.cpp source file, which is part of the widely-used open-source library for reading and writing image metadata. The flaw manifests when the library processes specially crafted image files that contain malformed data structures, specifically targeting the unsigned long to data conversion mechanism. This vulnerability demonstrates a classic memory safety issue that can be exploited by remote attackers to disrupt the normal operation of applications relying on Exiv2 for image metadata handling.
The technical implementation of this vulnerability stems from insufficient bounds checking during the processing of image metadata fields. When Exiv2 encounters a crafted image file with manipulated data values, the Exiv2::ul2Data function fails to properly validate the size of data being processed before attempting to allocate heap memory. This lack of input validation creates a condition where maliciously constructed metadata values can cause the library to write beyond allocated memory boundaries, resulting in a heap buffer overflow. The vulnerability is particularly dangerous because it can be triggered through standard image file processing operations, making it accessible to attackers who merely need to craft a malicious image file without requiring special privileges or direct system access. This flaw directly maps to CWE-121 Heap-based Buffer Overflow, which is categorized under the broader category of memory safety issues in the Common Weakness Enumeration framework.
The operational impact of CVE-2018-17230 extends far beyond simple denial of service conditions, as it can potentially enable more sophisticated attacks depending on the environment where vulnerable applications are deployed. Applications that utilize Exiv2 for processing user-uploaded images, such as content management systems, photo sharing platforms, and digital asset management tools, become vulnerable to remote code execution if attackers can leverage this buffer overflow for exploitation. The heap corruption caused by this vulnerability can lead to unpredictable application behavior, crashes, and in some cases, may provide attackers with opportunities to execute arbitrary code on affected systems. This risk is exacerbated by the widespread adoption of Exiv2 across numerous applications and platforms, making the potential attack surface extensive and potentially affecting thousands of systems that process image metadata. The vulnerability aligns with ATT&CK technique T1203, which involves the exploitation of memory corruption vulnerabilities to gain unauthorized access to systems.
Mitigation strategies for this vulnerability require immediate action from system administrators and software maintainers to update to patched versions of the Exiv2 library. The official fix involves implementing proper bounds checking within the Exiv2::ul2Data function to prevent excessive memory allocation based on malformed input data. Organizations should prioritize updating their Exiv2 installations to version 0.27 or later, where the buffer overflow has been addressed through enhanced input validation mechanisms. Additionally, implementing proper image file validation and sanitization processes can provide defense-in-depth measures, particularly for applications that must process untrusted image files from external sources. Network-based mitigations such as implementing file type validation and content filtering can help reduce the risk of exploitation by preventing malicious image files from reaching systems that rely on Exiv2 for metadata processing. Regular security audits and vulnerability assessments should be conducted to ensure that all dependencies using Exiv2 are properly updated and that no other similar buffer overflow vulnerabilities exist within the application stack. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and implementing robust input validation practices in all software components that handle external data processing.