CVE-2018-19210 in LibTIFF
Summary
by MITRE
In LibTIFF 4.0.9, there is a NULL pointer dereference in the TIFFWriteDirectorySec function in tif_dirwrite.c that will lead to a denial of service attack, as demonstrated by tiffset.
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Analysis
by VulDB Data Team • 06/05/2023
The vulnerability identified as CVE-2018-19210 represents a critical null pointer dereference flaw within the LibTIFF library version 4.0.9. This issue specifically affects the TIFFWriteDirectorySec function located in the tif_dirwrite.c source file, creating a condition where the application crashes when attempting to write directory structures to TIFF image files. The vulnerability manifests during normal operation when the tiffset utility processes malformed or specially crafted TIFF files, leading to an abrupt termination of the targeted process. This type of flaw falls under the category of software reliability issues that can be exploited to perform denial of service attacks against systems utilizing the affected library.
The technical nature of this vulnerability stems from insufficient input validation and error handling within the TIFF directory writing mechanism. When the TIFFWriteDirectorySec function processes certain directory entries, it fails to properly validate pointer references before dereferencing them, resulting in a null pointer access attempt. This condition occurs because the function assumes certain data structures will contain valid pointers, but in malformed TIFF files, these assumptions prove incorrect. The flaw is particularly dangerous because it can be triggered through normal file processing operations without requiring special privileges or complex attack vectors, making it accessible to potential attackers. The vulnerability directly maps to CWE-476, which describes null pointer dereference conditions in software implementations, and represents a classic example of improper input validation leading to system instability.
From an operational perspective, this vulnerability creates significant risk for systems that rely on LibTIFF for image processing operations, particularly those handling untrusted input from external sources. The denial of service impact means that legitimate users may experience service interruption when attempting to process TIFF files, potentially leading to cascading failures in image processing pipelines, document management systems, or web applications that depend on the affected library. Attackers can exploit this vulnerability by crafting malicious TIFF files that, when processed by applications using LibTIFF 4.0.9, will trigger the null pointer dereference and cause the application to crash. This makes the vulnerability particularly dangerous in environments where automated processing or user-uploaded content is common, as it can be used to disrupt services without requiring elevated privileges. The ATT&CK framework categorizes this type of vulnerability under the 'Software Dependencies' tactic, as it exploits weaknesses in commonly used third-party libraries that form part of the attack surface.
The mitigation strategy for CVE-2018-19210 involves immediate upgrading of the LibTIFF library to version 4.0.10 or later, where the null pointer dereference has been addressed through proper input validation and error handling mechanisms. System administrators should prioritize patching affected systems, particularly those handling user-uploaded content or processing external image files. Additionally, implementing input validation measures at the application level can provide defense in depth, ensuring that TIFF files are properly validated before being passed to the LibTIFF library functions. Organizations should also consider implementing monitoring and alerting for unusual process termination patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date third-party libraries and the potential for seemingly minor flaws to create significant security risks in widely-used software components. Regular security assessments and vulnerability management processes should include thorough evaluation of all library dependencies to prevent similar issues from affecting system security posture.