CVE-2016-6132 in GD Graphics Library
Summary
by MITRE
The gdImageCreateFromTgaCtx function in the GD Graphics Library (aka libgd) before 2.2.3 allows remote attackers to cause a denial of service (out-of-bounds read) via a crafted TGA file.
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Analysis
by VulDB Data Team • 09/13/2022
The vulnerability identified as CVE-2016-6132 resides within the GD Graphics Library, specifically in the gdImageCreateFromTgaCtx function which processes TGA image files. This flaw represents a critical security issue that affects versions prior to 2.2.3 of the library. The vulnerability manifests as an out-of-bounds read condition that can be exploited by remote attackers through the careful crafting of TGA image files, potentially leading to system instability and denial of service scenarios.
The technical implementation of this vulnerability stems from inadequate input validation within the TGA file parsing logic. When the gdImageCreateFromTgaCtx function processes a malformed TGA file, it fails to properly validate the header fields and data structures contained within the file format. This deficiency allows an attacker to construct a TGA file with maliciously crafted metadata that causes the library to attempt reading memory locations beyond the allocated buffer boundaries. The out-of-bounds memory access occurs during the parsing phase when the function attempts to interpret the image dimensions, color depth, and other header parameters without sufficient validation checks.
From an operational perspective, this vulnerability presents significant risks to systems that rely on the GD library for image processing tasks. Applications that accept user-uploaded TGA images or process images from untrusted sources become vulnerable to this attack vector. The denial of service impact can be substantial as a single malicious TGA file can cause the application to crash or become unresponsive, potentially affecting service availability for legitimate users. This vulnerability is particularly concerning in web applications where image upload functionality is present, as it can be exploited through simple file uploads without requiring complex exploitation techniques.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in software implementations. This weakness specifically impacts the integrity and availability of systems that utilize the affected library, as demonstrated by the potential for remote attackers to trigger system instability through crafted input files. The ATT&CK framework categorizes this as a privilege escalation technique through resource exhaustion and service disruption, as the vulnerability can be leveraged to cause system-wide availability issues. Organizations using the GD library in their applications should prioritize immediate patching to address this vulnerability and prevent potential exploitation.
Mitigation strategies include upgrading to libgd version 2.2.3 or later, which contains the necessary fixes for this vulnerability. Additionally, implementing input validation and sanitization measures for all TGA file processing can provide defense-in-depth protection. Organizations should also consider implementing file type verification and size limits for uploaded images to reduce the attack surface. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues in other graphics processing libraries and image handling components within the application stack.