CVE-2016-3633 in LibTIFF
Summary
by MITRE
The setrow function in the thumbnail tool in LibTIFF 4.0.6 and earlier allows remote attackers to cause a denial of service (out-of-bounds read) via vectors related to the src variable.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability identified as CVE-2016-3633 resides within the LibTIFF library version 4.0.6 and earlier, specifically within the thumbnail tool's setrow function. This flaw represents a critical security issue that enables remote attackers to execute denial of service attacks through out-of-bounds read conditions. The vulnerability manifests when processing specially crafted TIFF image files that contain malformed thumbnail data, particularly affecting the src variable handling within the setrow function. The root cause stems from inadequate input validation and boundary checking mechanisms that fail to properly sanitize or verify the dimensions and content of thumbnail data during processing operations.
From a technical perspective, the vulnerability constitutes a classic buffer over-read scenario where the setrow function attempts to access memory locations beyond the allocated bounds of the source data buffer. This occurs when the thumbnail tool processes image files with malformed or oversized thumbnail sections that exceed expected parameter limits. The flaw operates at the intersection of improper input validation and memory management, where the src variable reference becomes invalid due to unchecked boundary conditions. This type of vulnerability maps directly to CWE-125: Out-of-bounds Read, which is categorized under the broader class of memory safety issues affecting software systems. The vulnerability's exploitation requires minimal privileges and can be executed remotely through network-based file processing, making it particularly dangerous in environments where automated image processing occurs.
The operational impact of CVE-2016-3633 extends beyond simple denial of service, as it can potentially lead to system instability, application crashes, and resource exhaustion across various platforms that utilize LibTIFF for image processing. Systems commonly affected include web servers, image processing applications, and content management systems that handle user-uploaded TIFF files without proper sanitization. The vulnerability's remote exploitability means that attackers can trigger the condition through network-accessible services, potentially leading to cascading failures in applications that depend on stable image processing capabilities. From an attack framework perspective, this vulnerability aligns with ATT&CK technique T1499.004: Endpoint Denial of Service, specifically targeting the availability of image processing services through memory corruption attacks.
Mitigation strategies for CVE-2016-3633 primarily involve immediate patching of affected LibTIFF versions to 4.0.7 or later, where the vulnerability has been addressed through improved input validation and boundary checking mechanisms. Organizations should implement comprehensive input sanitization policies for all image file processing, including mandatory validation of thumbnail dimensions and content before processing. Network-based defenses can include implementing file type restrictions, content scanning, and sandboxed processing environments to isolate vulnerable applications. Additionally, monitoring systems should be configured to detect unusual processing patterns that may indicate exploitation attempts, while regular security audits should verify that all dependencies are updated to secure versions. The vulnerability demonstrates the importance of maintaining up-to-date third-party libraries and implementing robust security controls around file processing operations, particularly in internet-facing services where user-provided content is processed without proper validation.