CVE-2020-21675 in fig2dev
Summary
by MITRE • 08/11/2021
A stack-based buffer overflow in the genptk_text component in genptk.c of fig2dev 3.2.7b allows attackers to cause a denial of service (DOS) via converting a xfig file into ptk format.
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Analysis
by VulDB Data Team • 08/15/2021
The vulnerability identified as CVE-2020-21675 represents a critical stack-based buffer overflow flaw within the fig2dev tool suite version 3.2.7b specifically affecting the genptk_text component in the genptk.c source file. This issue arises during the conversion process when xfig files are transformed into ptk format, creating a pathway for malicious actors to exploit the software's memory handling mechanisms. The vulnerability stems from inadequate input validation and bounds checking within the buffer allocation logic, allowing attackers to craft specially malformed xfig input files that trigger the overflow condition when processing text elements within the conversion pipeline. The flaw manifests as a stack-based buffer overflow because the application fails to properly validate the length of text data before copying it into fixed-size stack buffers, creating a condition where attacker-controlled data can overwrite adjacent stack memory locations.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more sophisticated attack vectors. When exploited, the buffer overflow can cause the fig2dev application to crash or behave unpredictably, resulting in complete service disruption for systems relying on this tool for graphic file conversions. The vulnerability is particularly concerning because fig2dev is commonly used in automated workflows and server environments where continuous operation is critical, making denial of service attacks potentially disruptive to business operations. The attack surface is widened by the fact that the vulnerability can be triggered through routine file conversion operations, meaning that simply processing untrusted xfig files could lead to system compromise. From a cybersecurity perspective, this vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions where insufficient bounds checking allows data to overflow into adjacent memory locations.
The exploitation of this vulnerability requires an attacker to prepare a malicious xfig file containing oversized text elements that exceed the allocated buffer space in the genptk_text component. Once processed by fig2dev, the overflow causes the program to terminate abnormally or potentially execute arbitrary code if the overflow can be carefully crafted to overwrite critical program control structures. This type of vulnerability is particularly dangerous in environments where fig2dev is used with untrusted input, such as web applications accepting file uploads or automated processing systems handling user-generated content. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and execution techniques, as attackers can leverage buffer overflows to gain unauthorized access to systems or disrupt service availability. Organizations should consider this vulnerability as part of broader application security testing protocols, particularly focusing on input validation and memory safety mechanisms within conversion tools and graphic processing applications.
Mitigation strategies for CVE-2020-21675 should prioritize immediate patching of affected fig2dev installations 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 sanitize xfig files before processing, particularly focusing on text element length restrictions and malformed data detection. Network segmentation and access controls should limit exposure to systems running fig2dev, especially when processing untrusted files from external sources. Additionally, organizations should establish monitoring protocols to detect abnormal application behavior or frequent crashes that might indicate exploitation attempts. The vulnerability highlights the importance of proper memory management practices and input validation in open source software, emphasizing that even widely used tools can contain critical security flaws requiring regular security assessments and updates to maintain system integrity and prevent exploitation by malicious actors.