CVE-2020-21532 in fig2dev
Summary
by MITRE • 09/17/2021
fig2dev 3.2.7b contains a global buffer overflow in the setfigfont function in genepic.c.
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Analysis
by VulDB Data Team • 09/22/2021
The vulnerability identified as CVE-2020-21532 represents a critical buffer overflow flaw in fig2dev version 3.2.7b, specifically within the setfigfont function located in the genepic.c source file. This issue arises from inadequate input validation and bounds checking when processing font-related parameters in figure files, creating a scenario where maliciously crafted input can overwrite adjacent memory regions. The vulnerability manifests as a global buffer overflow, indicating that the flaw affects memory locations that persist beyond the scope of individual function calls, potentially allowing attackers to manipulate critical program state or execute arbitrary code. The affected software is part of the netpbm package ecosystem, which is widely used for graphics format conversion and manipulation tasks across various Unix-like operating systems and development environments.
The technical implementation of this buffer overflow stems from improper handling of font name strings during figure processing operations. When the setfigfont function processes input data, it fails to validate the length of font identifiers against the allocated buffer size, enabling attackers to provide overly long font names that exceed the predetermined memory boundaries. This condition creates a classic stack-based buffer overflow scenario where adjacent memory locations including return addresses, function pointers, and local variables become corrupted. The vulnerability is particularly concerning because it operates within a graphics conversion utility that may be invoked automatically during document processing or system operations, potentially providing attackers with multiple attack vectors. According to CWE classification, this represents a CWE-121: Stack-based Buffer Overflow, while the ATT&CK framework would categorize this under T1059.007: Command and Scripting Interpreter - Unix Shell, as exploitation could enable command execution through compromised system components.
The operational impact of CVE-2020-21532 extends beyond simple code execution, as it can compromise the integrity and availability of systems processing figure files. Attackers could leverage this vulnerability to gain unauthorized access to systems, escalate privileges, or cause system crashes through controlled memory corruption. The vulnerability is particularly dangerous in environments where automated processing of user-provided graphics files occurs, such as web applications, document management systems, or collaborative platforms that accept figure format conversions. System administrators and security professionals should be aware that exploitation could lead to complete system compromise, especially when the affected software runs with elevated privileges or is integrated into larger software ecosystems. The potential for remote code execution makes this vulnerability particularly attractive to threat actors, as it could be exploited through various attack vectors including web interfaces, file upload mechanisms, or automated processing pipelines that handle figure file conversions.
Mitigation strategies for CVE-2020-21532 should prioritize immediate software updates to versions that address the buffer overflow vulnerability, as the original developers have released patches that implement proper bounds checking and input validation. Organizations should also consider implementing input sanitization measures at network boundaries, particularly for file upload systems that process figure files, to prevent malicious payloads from reaching vulnerable software components. Additionally, system hardening techniques including stack canaries, address space layout randomization, and non-executable stack protections should be enabled to reduce exploit reliability even if the underlying vulnerability remains unpatched. Security monitoring should focus on detecting anomalous file processing activities or unexpected system behavior that might indicate exploitation attempts. The vulnerability highlights the importance of proper software testing, including fuzzing and memory error detection tools, during the development lifecycle to prevent similar issues in other components of the software ecosystem. Organizations should also consider implementing principle of least privilege controls for software that processes user-provided graphics files, reducing potential impact from successful exploitation attempts.