CVE-2016-3620 in LibTIFF
Summary
by MITRE
The ZIPEncode function in tif_zip.c in the bmp2tiff tool in LibTIFF 4.0.6 and earlier, when the "-c zip" option is used, allows remote attackers to cause a denial of service (buffer over-read) via a crafted BMP image.
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Analysis
by VulDB Data Team • 07/13/2022
The vulnerability identified as CVE-2016-3620 affects the LibTIFF library version 4.0.6 and earlier, specifically within the bmp2tiff tool's ZIPEncode function located in tif_zip.c. This flaw manifests when the tool processes BMP images with the "-c zip" compression option, creating a condition where remote attackers can trigger a buffer over-read attack through carefully crafted malicious BMP files. The issue stems from inadequate input validation and memory management within the compression routine that handles TIFF image encoding operations.
The technical implementation of this vulnerability involves a classic buffer over-read scenario where the ZIPEncode function fails to properly bounds-check data during the decompression process. When a malicious BMP image is processed with zip compression, the function attempts to read beyond the allocated memory buffer boundaries, potentially accessing uninitialized or adjacent memory regions. This memory corruption can result in unpredictable behavior including application crashes, segmentation faults, or in some cases, potential information disclosure. The vulnerability operates at the intersection of image processing and memory safety, making it particularly dangerous in environments where image processing libraries handle untrusted input from external sources.
From an operational perspective, this vulnerability presents significant risks to systems that utilize the bmp2tiff tool for image conversion, particularly in web applications, content management systems, or any service that accepts user-uploaded BMP images for processing. The remote exploitation capability means attackers can potentially disrupt services without requiring local access, making this a critical concern for network-facing applications. The denial of service impact can be substantial, especially in high-traffic environments where image processing is a frequent operation, potentially leading to service degradation or complete system unavailability.
Mitigation strategies for CVE-2016-3620 should focus on immediate patching of affected LibTIFF versions to 4.0.7 or later, where the buffer over-read issue has been resolved through proper bounds checking and memory management. Organizations should also implement input validation measures, including file type verification and size limitations for image uploads, to reduce the attack surface. Additionally, deploying network segmentation and access controls can limit the potential impact of exploitation attempts. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and could be categorized under ATT&CK technique T1499.004 for endpoint denial of service attacks. Regular security assessments and vulnerability scanning should be conducted to identify other potentially affected components within the LibTIFF ecosystem, as similar issues may exist in related functions or other image processing libraries that handle similar compression formats.