CVE-2016-9540 in macOS
Summary
by MITRE
tools/tiffcp.c in libtiff 4.0.6 has an out-of-bounds write on tiled images with odd tile width versus image width. Reported as MSVR 35103, aka "cpStripToTile heap-buffer-overflow."
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Analysis
by VulDB Data Team • 11/20/2022
The vulnerability identified as CVE-2016-9540 resides within the libtiff library version 4.0.6, specifically in the tools/tiffcp.c component that handles image processing operations. This flaw manifests when processing tiled TIFF images where the tile width does not align perfectly with the overall image width, creating a scenario where the software attempts to write data beyond the allocated memory boundaries. The issue was originally reported as Microsoft Security Vulnerability Report 35103 and commonly referred to as "cpStripToTile heap-buffer-overflow" due to the nature of the memory corruption occurring during the tile conversion process. The vulnerability represents a classic buffer overflow condition that can potentially be exploited by malicious actors to execute arbitrary code or cause application crashes.
The technical root cause of this vulnerability stems from inadequate boundary checking within the tile processing logic of the tiffcp utility. When libtiff encounters a tiled image with an odd tile width that doesn't evenly divide the image width, the memory allocation calculations become misaligned, leading to writes that exceed the intended buffer limits. This condition occurs during the cpStripToTile function execution where the software fails to properly validate tile dimensions against the image boundaries before performing memory operations. The flaw falls under the CWE-787 weakness category, which specifically addresses out-of-bounds write vulnerabilities, and aligns with ATT&CK technique T1059.007 for executing malicious code through buffer overflow exploitation. The implementation error occurs in the memory management layer where tile coordinates and dimensions are not properly validated against the actual image dimensions before data copying operations.
The operational impact of this vulnerability extends across numerous applications that rely on libtiff for image processing, particularly those handling raster graphics in scientific imaging, medical imaging, document management systems, and digital photography workflows. An attacker could potentially craft malicious TIFF files with specifically designed odd tile dimensions to trigger the buffer overflow, leading to application instability, denial of service conditions, or more severe remote code execution scenarios. The vulnerability affects systems where libtiff is used as a library component in various software stacks, including web applications, image processing pipelines, and desktop software that handles TIFF format files. The heap-based nature of the overflow provides additional attack surface complexity since heap corruption can be leveraged for more sophisticated exploitation techniques, including information disclosure and privilege escalation scenarios.
Mitigation strategies for CVE-2016-9540 should prioritize immediate patching of affected libtiff installations to version 4.0.7 or later, which contains the necessary fixes for the boundary checking logic. Organizations should also implement input validation controls at application layers that process TIFF files, ensuring that all image dimensions are properly validated before being passed to libtiff processing functions. Network-based defenses can include content filtering systems that scan TIFF files for malformed structures, particularly those with irregular tile dimensions. Additionally, application sandboxing and memory protection mechanisms such as stack canaries, address space layout randomization, and data execution prevention should be enabled to reduce the effectiveness of potential exploitation attempts. System administrators should monitor for unusual file processing patterns and implement automated scanning of TIFF file inputs to identify potentially malicious payloads. The fix implemented in the patched version addresses the core issue by introducing proper boundary validation checks that ensure tile processing operations remain within allocated memory boundaries regardless of the tile width relative to image dimensions.