CVE-2018-17581 in Exiv2
Summary
by MITRE
CiffDirectory::readDirectory() at crwimage_int.cpp in Exiv2 0.26 has excessive stack consumption due to a recursive function, leading to Denial of service.
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Analysis
by VulDB Data Team • 05/19/2023
The vulnerability identified as CVE-2018-17581 represents a critical stack consumption issue within the Exiv2 image processing library version 0.26. This flaw exists in the CiffDirectory::readDirectory() function located in the crwimage_int.cpp source file, where a recursive implementation pattern creates an excessive stack allocation scenario that can be exploited to cause system instability. The vulnerability specifically affects the handling of CRW (Casio Raw) image files, which are proprietary raw image formats used by Casio digital cameras. When processing malformed or specially crafted CRW files, the recursive function call pattern leads to deep stack consumption that can eventually exhaust available stack memory resources.
The technical implementation of this vulnerability stems from the recursive nature of the CiffDirectory::readDirectory() function which traverses directory structures within CRW image files without proper depth limiting mechanisms. This recursive approach, while potentially elegant for certain directory traversal scenarios, becomes problematic when dealing with deeply nested or malformed directory structures that can be intentionally crafted to maximize recursive calls. The function does not implement any stack depth limits or iterative alternatives to prevent unbounded stack growth, making it susceptible to exploitation through carefully constructed input data. The vulnerability manifests as a stack overflow condition that occurs during the parsing of image metadata, particularly when the CRW file contains malformed directory entries that trigger excessive recursion.
The operational impact of CVE-2018-17581 extends beyond simple denial of service conditions, as it can be leveraged in broader attack scenarios that target applications relying on Exiv2 for image processing. Systems utilizing Exiv2 for image metadata extraction, particularly web applications, content management systems, or digital asset management platforms, become vulnerable to denial of service attacks when processing untrusted image files. Attackers can craft malicious CRW files that trigger the recursive function calls to consume all available stack space, causing application crashes or complete service unavailability. This vulnerability is particularly concerning in environments where automated image processing occurs, such as social media platforms, photo sharing services, or digital photography applications, as these systems may be subject to continuous exploitation attempts.
Mitigation strategies for CVE-2018-17581 should focus on both immediate remediation and architectural improvements to prevent similar issues in the future. The most direct approach involves upgrading to Exiv2 version 0.27 or later, where the recursive function has been replaced with an iterative implementation that prevents excessive stack consumption. Organizations should also implement input validation and sanitization measures to filter potentially malicious image files before processing, particularly those from untrusted sources. Additionally, runtime stack protection mechanisms such as stack canaries and stack overflow detection should be enabled where possible. The vulnerability aligns with CWE-674, which describes "Uncontrolled Recursion" as a weakness that can lead to stack overflow conditions, and may be categorized under ATT&CK technique T1499.004 for "Endpoint Denial of Service" in the context of service disruption attacks. System administrators should also consider implementing monitoring and alerting for unusual resource consumption patterns that may indicate exploitation attempts.