CVE-2017-9815 in LibTIFF
Summary
by MITRE
In LibTIFF 4.0.7, the TIFFReadDirEntryLong8Array function in libtiff/tif_dirread.c mishandles a malloc operation, which allows attackers to cause a denial of service (memory leak within the function _TIFFmalloc in tif_unix.c) via a crafted file.
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Analysis
by VulDB Data Team • 10/24/2024
The vulnerability identified as CVE-2017-9815 represents a critical memory management flaw within the LibTIFF library version 4.0.7, specifically within the TIFFReadDirEntryLong8Array function located in the libtiff/tif_dirread.c source file. This issue manifests as a memory leak condition that occurs when the function improperly handles memory allocation operations, creating a persistent resource exhaustion scenario that can severely impact system stability and availability. The flaw is particularly concerning because it operates within the core file parsing functionality of the library, making it exploitable through seemingly innocuous TIFF image files that contain crafted malicious structures. The vulnerability directly affects the _TIFFmalloc function in tif_unix.c, which serves as the primary memory allocation mechanism within the library's Unix-based implementations, creating a cascading effect where allocated memory resources are not properly released back to the system.
The technical exploitation of this vulnerability occurs when a maliciously crafted TIFF file is processed by an application relying on LibTIFF for image handling. During the directory entry reading process, the TIFFReadDirEntryLong8Array function attempts to allocate memory for large 8-byte integer arrays but fails to properly validate or handle the malloc operation results. This memory allocation failure leads to a gradual accumulation of unreleased memory segments within the application's heap, eventually causing memory exhaustion and subsequent denial of service conditions. The flaw operates at the intersection of memory management and file parsing, where the library's failure to properly handle edge cases in file structure parsing creates a resource leak that can be systematically exploited to consume available system memory. The vulnerability's impact is amplified by the widespread use of LibTIFF across numerous applications and systems, including web servers, image processing software, and document management systems that handle TIFF file formats.
From an operational perspective, this vulnerability presents a significant risk to system availability and stability, particularly in environments where applications continuously process user-uploaded or externally sourced TIFF files. The memory leak can occur silently over time, with the impact becoming apparent only when system resources are exhausted, leading to application crashes, service interruptions, and potential system-wide instability. The vulnerability aligns with CWE-401, which specifically addresses improper handling of memory allocation failures, and demonstrates characteristics consistent with attack patterns found in the MITRE ATT&CK framework under the Privilege Escalation and Resource Exhaustion tactics. Organizations utilizing LibTIFF in their infrastructure face the risk of sustained denial of service attacks where adversaries can systematically consume system resources through carefully crafted TIFF files, potentially leading to complete service unavailability. The vulnerability's exploitation does not require elevated privileges, making it particularly dangerous as it can be leveraged by unauthenticated attackers to disrupt services.
Mitigation strategies for CVE-2017-9815 primarily focus on immediate patching and updates to LibTIFF library versions that contain the corrected memory management implementation. System administrators should prioritize updating all affected applications to use LibTIFF 4.0.8 or later versions where the memory allocation handling has been properly addressed. Additionally, implementing input validation and sanitization measures at the application level can provide defense-in-depth protection, including restricting file size limits, implementing timeout mechanisms for file processing, and employing sandboxed environments for image file handling. Network-level protections such as content filtering and file type validation can help prevent malicious TIFF files from reaching vulnerable applications, while monitoring systems should be configured to detect unusual memory consumption patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper memory management in security-critical libraries and highlights the need for thorough code review and testing of allocation/deallocation patterns in file processing components.