CVE-2020-21681 in fig2dev
Summary
by MITRE • 08/11/2021
A global buffer overflow in the set_color component in genge.c of fig2dev 3.2.7b allows attackers to cause a denial of service (DOS) via converting a xfig file into ge format.
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Analysis
by VulDB Data Team • 08/15/2021
The vulnerability identified as CVE-2020-21681 represents a critical buffer overflow condition within the fig2dev conversion utility version 3.2.7b specifically affecting the set_color component in the genge.c source file. This flaw manifests as a global buffer overflow that occurs during the conversion process when transforming xfig files into ge format. The vulnerability stems from inadequate input validation and memory management practices within the color setting functionality of the fig2dev tool, which is commonly used for converting xfig vector graphics files to various output formats. The affected component processes color information during the conversion workflow, where insufficient bounds checking allows attackers to provide maliciously crafted input that exceeds the allocated buffer space.
The technical exploitation of this vulnerability enables attackers to trigger a denial of service condition by supplying specially crafted xfig files that contain oversized color specifications or malformed color data. When the set_color function processes these inputs without proper boundary verification, the excess data overflows into adjacent memory regions, potentially causing the application to crash or behave unpredictably. This buffer overflow condition falls under the category of CWE-121, which describes stack-based buffer overflow vulnerabilities, though it manifests as a global buffer overflow in this specific implementation. The vulnerability is particularly concerning because fig2dev is often used in automated workflows and document processing systems where such crashes could disrupt legitimate operations and create availability issues for users relying on the tool.
The operational impact of CVE-2020-21681 extends beyond simple service disruption to potentially enable more sophisticated attack vectors. While the primary effect is denial of service, the buffer overflow condition creates opportunities for memory corruption that could theoretically be leveraged for code execution under certain circumstances. Attackers could exploit this vulnerability in environments where fig2dev is executed with elevated privileges or in automated processing pipelines where malicious input might be accepted from untrusted sources. The vulnerability is particularly dangerous in web applications or document processing services that utilize fig2dev for rendering or conversion services, as it could allow remote attackers to cause system instability or resource exhaustion. From an attack perspective, this vulnerability aligns with ATT&CK technique T1203, which involves legitimate user privileges to perform denial of service attacks through application-level vulnerabilities.
Mitigation strategies for CVE-2020-21681 should prioritize immediate patching of the fig2dev utility to version 3.2.7c or later, which contains the necessary fixes for the buffer overflow condition. System administrators should implement input validation measures to filter or sanitize xfig files before processing them through fig2dev, particularly focusing on color specification data that could trigger the vulnerable code path. Additionally, deployment environments should consider implementing sandboxing or containerization of fig2dev processes to limit the potential impact of any exploitation attempts. Network-level controls can help by blocking or restricting access to fig2dev conversion services from untrusted networks or users. The vulnerability demonstrates the importance of proper memory management and input validation practices, particularly in utility applications that process untrusted data formats. Organizations should conduct thorough vulnerability assessments of their fig2dev installations and ensure that all systems using this tool are updated to prevent exploitation attempts. Regular security monitoring and incident response procedures should be implemented to detect potential exploitation attempts targeting this vulnerability.