CVE-2016-3991 in LibTIFF
Summary
by MITRE
Heap-based buffer overflow in the loadImage function in the tiffcrop tool in LibTIFF 4.0.6 and earlier allows remote attackers to cause a denial of service (out-of-bounds write) or execute arbitrary code via a crafted TIFF image with zero tiles.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability CVE-2016-3991 represents a critical heap-based buffer overflow affecting the tiffcrop tool within LibTIFF version 4.0.6 and earlier. This flaw exists within the loadImage function where improper input validation leads to memory corruption when processing specially crafted TIFF images containing zero tiles. The vulnerability demonstrates characteristics consistent with CWE-121, heap-based buffer overflow, where insufficient bounds checking allows attackers to write beyond allocated memory boundaries. The issue falls under the broader category of memory safety vulnerabilities that can lead to both denial of service conditions and arbitrary code execution, making it particularly dangerous in security contexts.
The technical exploitation of this vulnerability occurs when the tiffcrop utility processes a malformed TIFF file with zero tile specifications. The loadImage function fails to properly validate the tile count parameter, allowing an attacker to manipulate memory layout through crafted input data. When the application attempts to allocate memory for tile processing without proper bounds verification, it creates a condition where subsequent memory writes can overwrite adjacent heap regions. This memory corruption can manifest as out-of-bounds writes that may trigger segmentation faults leading to denial of service, or more critically, allow attackers to execute arbitrary code by overwriting function pointers or return addresses. The vulnerability aligns with ATT&CK technique T1203, Exploitation for Client Execution, as it enables remote code execution through file processing.
The operational impact of CVE-2016-3991 extends beyond simple denial of service scenarios to encompass full system compromise when exploited. Systems utilizing LibTIFF for image processing, including web applications, image servers, and document management systems, become vulnerable to remote exploitation. The vulnerability's remote attack vector means that simply opening or processing a malicious TIFF file can trigger the exploit, making it particularly dangerous in environments where users might encounter untrusted image files. Organizations relying on LibTIFF for image handling, including content management systems, digital asset management platforms, and image processing pipelines, face significant risk if their systems remain unpatched. The vulnerability affects not only the tiffcrop tool but potentially other tools within the LibTIFF library that share similar code patterns, creating a broader attack surface.
Mitigation strategies for CVE-2016-3991 primarily focus on immediate patching of affected LibTIFF versions to 4.0.7 or later where the buffer overflow has been addressed through proper input validation and bounds checking. System administrators should implement strict file validation policies, particularly for TIFF files received from untrusted sources, and consider deploying automated scanning tools to detect potentially malicious image files. Network segmentation and access controls can limit the impact of successful exploitation attempts. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all systems using affected LibTIFF versions and implement monitoring for suspicious file processing activities. The fix typically involves implementing proper bounds checking in the tile count validation logic and ensuring that heap allocations are properly sized based on validated input parameters, addressing the root cause of the vulnerability through defensive programming practices and adherence to secure coding standards.