CVE-2016-3658 in LibTIFF
Summary
by MITRE
The TIFFWriteDirectoryTagLongLong8Array function in tif_dirwrite.c in the tiffset tool in LibTIFF 4.0.6 and earlier allows remote attackers to cause a denial of service (out-of-bounds read) via vectors involving the ma variable.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability identified as CVE-2016-3658 resides within the LibTIFF library version 4.0.6 and earlier, specifically affecting the tiffset tool's TIFFWriteDirectoryTagLongLong8Array function. This flaw manifests in the tif_dirwrite.c source file where improper input validation leads to an out-of-bounds read condition when processing the ma variable. The issue occurs during the handling of TIFF directory tag operations, particularly when dealing with long long 8 arrays, making it a critical concern for systems relying on proper TIFF file processing. The vulnerability represents a classic buffer over-read scenario that can be exploited remotely without requiring authentication or specialized privileges.
The technical implementation of this vulnerability stems from inadequate bounds checking within the TIFFWriteDirectoryTagLongLong8Array function where the ma variable is processed without proper validation of array boundaries. When an attacker crafts a malicious TIFF file with malformed data structures, the function fails to properly validate the size or bounds of the ma variable before attempting to read from memory locations beyond the allocated array boundaries. This condition results in an out-of-bounds memory read operation that can cause the application to crash or behave unpredictably. The flaw is categorized under CWE-129 as an insufficient bounds check, specifically manifesting as an out-of-bounds read in the context of array manipulation. The vulnerability is particularly concerning because it can be triggered through normal file processing operations, making it a potential vector for denial of service attacks against systems that process TIFF files.
Operationally, this vulnerability can be exploited by remote attackers to perform denial of service attacks against systems running vulnerable versions of LibTIFF. The impact extends beyond simple application crashes to potentially affecting system availability, especially in environments where TIFF file processing is automated or part of critical workflows. Systems that process untrusted TIFF files, such as document management systems, image servers, or content management platforms, become vulnerable to this attack vector. The exploitability of this vulnerability is relatively straightforward, requiring only the creation of a malicious TIFF file that triggers the specific code path involving the ma variable. The attack can be executed without user interaction or authentication, making it particularly dangerous in environments where automated file processing occurs. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and represents a common exploitation pattern targeting library functions in image processing software.
Mitigation strategies for CVE-2016-3658 focus primarily on upgrading to patched versions of LibTIFF, specifically versions 4.0.7 and later where the bounds checking has been properly implemented. Organizations should conduct comprehensive vulnerability assessments to identify systems running vulnerable versions of the library and prioritize patching efforts accordingly. Additionally, implementing input validation measures at the application level can provide defense in depth, ensuring that TIFF files are properly sanitized before processing. Network segmentation and access controls can limit exposure by restricting access to systems that process TIFF files to trusted networks and users. Security monitoring should be enhanced to detect unusual patterns of file processing that might indicate exploitation attempts, particularly around TIFF file operations. System administrators should also consider implementing automated patch management processes to ensure timely deployment of security updates. The vulnerability serves as a reminder of the importance of proper input validation and bounds checking in library functions, particularly those handling binary file formats that are commonly processed in enterprise environments.