CVE-2016-4796 in OpenJPEG
Summary
by MITRE
Heap-based buffer overflow in the color_cmyk_to_rgb in common/color.c in OpenJPEG before 2.1.1 allows remote attackers to cause a denial of service (crash) via a crafted .j2k file.
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Analysis
by VulDB Data Team • 11/11/2022
The vulnerability identified as CVE-2016-4796 represents a critical heap-based buffer overflow within the OpenJPEG library's color conversion functionality. This flaw exists in the color_cmyk_to_rgb function located in the common/color.c source file and affects all versions prior to 2.1.1. The vulnerability stems from inadequate input validation when processing color space conversions, specifically in how the library handles CMYK to RGB color transformations. Attackers can exploit this weakness by crafting malicious .j2k files that contain malformed color data, triggering the buffer overflow during the decompression process.
The technical implementation of this vulnerability involves the manipulation of heap memory allocation during color space conversion operations. When the color_cmyk_to_rgb function processes a crafted input, it fails to properly validate the bounds of memory allocations, leading to a situation where more data is written to a heap buffer than it can accommodate. This overflow condition creates a crash scenario that results in a denial of service condition, effectively rendering the affected application unusable. The vulnerability is particularly concerning because it operates at the library level, meaning any application that utilizes OpenJPEG for image processing becomes vulnerable to this attack vector.
From an operational perspective, this vulnerability presents significant risks to systems that process untrusted image files, particularly in web applications, document management systems, and image processing pipelines. The remote exploitation capability means that attackers can trigger the vulnerability without requiring local access to the target system. The denial of service impact can be severe in environments where image processing is critical to business operations, potentially leading to service disruption and availability issues. This vulnerability aligns with CWE-121, heap-based buffer overflow, and demonstrates characteristics consistent with ATT&CK technique T1203, Exploitation for Client Execution, as it enables remote code execution through application crashes.
The exploitation of CVE-2016-4796 requires crafting a specific .j2k file that triggers the buffer overflow during the color conversion process. Attackers typically construct malicious color data that exceeds the allocated buffer size, causing memory corruption that leads to application termination. Mitigation strategies include immediate upgrading to OpenJPEG version 2.1.1 or later, which contains the necessary patches to address the buffer overflow condition. Organizations should also implement input validation measures and sandboxing techniques when processing image files from untrusted sources. Additionally, network segmentation and application whitelisting can help reduce the attack surface, while regular security assessments and vulnerability scanning should be conducted to identify potential exposure points. The fix implemented in version 2.1.1 involves proper bounds checking and memory allocation validation within the color conversion functions, ensuring that all input data is properly validated before processing.