CVE-2018-5784 in LibTIFF
Summary
by MITRE
In LibTIFF 4.0.9, there is an uncontrolled resource consumption in the TIFFSetDirectory function of tif_dir.c. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted tif file. This occurs because the declared number of directory entries is not validated against the actual number of directory entries.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability described in CVE-2018-5784 represents a critical resource consumption flaw within the LibTIFF library version 4.0.9, specifically affecting the TIFFSetDirectory function in the tif_dir.c source file. This issue manifests as an uncontrolled resource consumption problem that can be exploited remotely through the manipulation of crafted tif files, ultimately leading to denial of service conditions. The vulnerability stems from a fundamental validation failure where the library does not properly verify that the declared number of directory entries in a TIFF file matches the actual number of directory entries present in the file structure. This discrepancy creates a scenario where the library's memory allocation and processing mechanisms become overwhelmed by malformed input data, resulting in excessive resource utilization that can incapacitate systems relying on the affected library.
The technical implementation of this vulnerability occurs at the directory parsing level within the TIFF file format handling code. When the TIFFSetDirectory function processes a file, it relies on metadata information that declares how many directory entries should exist within the file's structure. However, the absence of proper validation means that if an attacker crafts a file where the declared entry count significantly exceeds or differs from the actual entries present, the library's internal processing routines will attempt to allocate memory and process entries based on the inflated count. This leads to memory exhaustion, CPU resource overconsumption, and ultimately system instability or complete service unavailability. The flaw operates as a classic resource exhaustion attack vector that exploits the library's trust in file metadata without proper verification mechanisms.
From an operational impact perspective, this vulnerability poses significant risks to systems that process or handle TIFF image files, particularly those exposed to untrusted input sources. Applications built using LibTIFF 4.0.9, including image processing systems, document management platforms, and web applications that accept TIFF uploads, become vulnerable to denial of service attacks. The remote exploitation capability means that attackers can trigger the vulnerability from external networks without requiring local system access, making it particularly dangerous for web-facing services. The resource consumption aspect can affect not only individual processes but potentially entire systems if multiple concurrent attacks occur or if the vulnerability is leveraged in a distributed manner, leading to cascading service failures and operational disruptions.
The vulnerability aligns with CWE-770, which describes the allocation of resources without proper limits or controls, and represents a clear violation of secure coding practices that should include input validation and resource management controls. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique for "Endpoint Denial of Service" and potentially T1595.001 for "Scanning for Vulnerabilities" as attackers may first identify systems using vulnerable LibTIFF versions before deploying exploitation payloads. The remediation strategy requires immediate patching of the LibTIFF library to version 4.0.10 or later, which includes proper validation of directory entry counts. Additionally, system administrators should implement input validation measures, monitor for unusual resource consumption patterns, and consider deploying intrusion detection systems that can identify suspicious TIFF file processing activities. Organizations should also conduct thorough vulnerability assessments to identify all systems using affected library versions and establish proper resource limits and timeouts for file processing operations to mitigate potential exploitation impacts.