CVE-2018-20030 in libexif
Summary
by MITRE
An error when processing the EXIF_IFD_INTEROPERABILITY and EXIF_IFD_EXIF tags within libexif version 0.6.21 can be exploited to exhaust available CPU resources.
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Analysis
by VulDB Data Team • 07/11/2023
The vulnerability identified as CVE-2018-20030 represents a critical resource exhaustion issue within the libexif library version 0.6.21 which is widely used for parsing exchangeable image file format data in digital photography applications. This flaw specifically targets the processing of two EXIF tags namely EXIF_IFD_INTEROPERABILITY and EXIF_IFD_EXIF which are integral components of digital image metadata structures. The vulnerability stems from inadequate input validation and processing logic within the library's parser implementation, creating a condition where malformed or specially crafted EXIF data can trigger excessive computational overhead during parsing operations.
The technical exploitation of this vulnerability occurs when applications utilizing libexif for image metadata processing encounter images containing malformed EXIF data structures within the targeted IFD (Image File Directory) sections. The flaw manifests as an algorithmic complexity issue where the parser enters into computationally expensive processing loops when handling these specific tag structures, leading to significant CPU resource consumption. This behavior is classified as a denial of service condition where legitimate system resources are consumed in a manner that prevents normal operation of affected applications and potentially impacts overall system performance.
From an operational perspective this vulnerability poses substantial risks to applications and systems that process digital imagery, including photo management software, web applications handling user-uploaded images, digital asset management systems, and content delivery networks. Attackers can exploit this vulnerability by crafting malicious image files that contain specially formatted EXIF data which will cause affected applications to consume excessive CPU cycles during image processing. The impact extends beyond individual application crashes to potentially affect entire service availability, particularly in high-volume environments where multiple image processing operations occur simultaneously.
The vulnerability aligns with CWE-400 which categorizes excessive resource consumption as a fundamental weakness in software design, and can be mapped to ATT&CK technique T1499.004 which covers resource exhaustion attacks targeting application availability. Organizations utilizing libexif version 0.6.21 should immediately implement mitigations including upgrading to patched library versions, implementing input validation measures, and deploying rate limiting controls on image processing operations. Additionally, security teams should monitor for potential exploitation attempts through anomalous CPU usage patterns and implement automated scanning of image uploads for malformed EXIF structures. The remediation process requires comprehensive testing of updated library versions to ensure compatibility with existing applications while maintaining the security posture against this specific resource exhaustion threat vector.