CVE-2017-14931 in OpenExif
Summary
by MITRE
ExifImageFile::readDQT in ExifImageFileRead.cpp in OpenExif 2.1.4 allows remote attackers to cause a denial of service (stack-based buffer over-read and application crash) via a crafted JPEG file.
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Analysis
by VulDB Data Team • 11/20/2019
The vulnerability identified as CVE-2017-14931 resides within the OpenExif library version 2.1.4, specifically in the ExifImageFile::readDQT function located in ExifImageFileRead.cpp. This flaw represents a critical stack-based buffer over-read condition that can be exploited by remote attackers to trigger a denial of service attack. The vulnerability manifests when the library processes specially crafted JPEG files that contain malformed quantization tables, which are part of the JPEG standard but become problematic when improperly structured within the image data.
The technical implementation of this vulnerability involves the readDQT function failing to properly validate the length of quantization tables during JPEG file parsing. When an attacker crafts a JPEG file with oversized or malformed DQT (Define Quantization Table) segments, the function attempts to read beyond the allocated buffer boundaries, resulting in a stack-based buffer over-read. This memory corruption condition causes the application to crash and terminate unexpectedly, effectively rendering the service unavailable to legitimate users. The flaw operates at the binary parsing level where the library does not perform adequate bounds checking before copying data into fixed-size buffers, making it susceptible to exploitation through carefully constructed input files.
From an operational impact perspective, this vulnerability poses significant risks to any application or system that relies on OpenExif for JPEG image processing and metadata extraction. The denial of service condition can be triggered remotely without requiring authentication, making it particularly dangerous in web applications, content management systems, or any service that accepts user-uploaded images. Attackers can exploit this vulnerability to disrupt services by uploading malicious JPEG files that cause the processing application to crash repeatedly, potentially leading to complete service unavailability. The vulnerability affects systems where OpenExif is integrated for image handling, including web servers, image processing pipelines, and digital asset management platforms.
The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which describes a condition where data is written beyond the bounds of a stack-allocated buffer, and it maps to ATT&CK technique T1499.004 Network Denial of Service within the context of service disruption. Organizations should implement immediate mitigations including updating to the latest version of OpenExif where this vulnerability has been patched, implementing input validation and sanitization for all uploaded image files, and deploying intrusion detection systems to monitor for exploitation attempts. Additionally, application-level defenses such as sandboxing image processing components and implementing proper error handling with graceful degradation should be considered. The fix typically involves adding proper bounds checking in the readDQT function to ensure that quantization table data does not exceed the expected buffer size before copying operations occur, thereby preventing the buffer over-read condition that leads to application crashes.