CVE-2018-19491 in Gnuplot
Summary
by MITRE
An issue was discovered in post.trm in Gnuplot 5.2.5. This issue allows an attacker to conduct a buffer overflow with an arbitrary amount of data in the PS_options function. This flaw is caused by a missing size check of an argument passed to the "set font" function. This issue occurs when the Gnuplot postscript terminal is used as a backend.
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Analysis
by VulDB Data Team • 06/11/2023
The vulnerability identified as CVE-2018-19491 represents a critical buffer overflow condition within the Gnuplot plotting software version 5.2.5, specifically affecting the postscript terminal functionality. This flaw exists within the post.trm module and manifests when the PS_options function processes data without proper size validation, creating an exploitable condition that can be leveraged by malicious actors to execute arbitrary code or cause system instability. The vulnerability is particularly concerning because it allows for an arbitrary amount of data to be fed into the buffer, potentially leading to complete system compromise when exploited correctly.
The technical root cause of this vulnerability stems from a missing size check in the argument validation process for the "set font" function within the postscript terminal implementation. When Gnuplot processes commands through the postscript terminal backend, the PS_options function fails to verify the length of input data before copying it into a fixed-size buffer, creating a classic buffer overflow scenario. This condition aligns with CWE-121, which describes stack-based buffer overflow vulnerabilities that occur when insufficient bounds checking is performed on data copied into fixed-length buffers. The flaw is particularly dangerous because it does not require specific input conditions beyond normal usage of the font setting functionality, making it accessible to attackers who can craft malicious input files or commands.
The operational impact of CVE-2018-19491 extends beyond simple denial of service scenarios, as it provides potential for remote code execution and system compromise when Gnuplot is used in environments where users can submit plotting commands or data files. Attackers can exploit this vulnerability by creating specially crafted input files that trigger the buffer overflow during postscript output generation, potentially allowing them to execute arbitrary code with the privileges of the user running Gnuplot. This vulnerability is particularly relevant in server environments where Gnuplot might process untrusted data from multiple sources, or in applications that use Gnuplot as a backend for data visualization. The attack surface is broadened by the fact that this issue can be triggered through legitimate use of the "set font" command, making it difficult to detect and prevent through simple input filtering approaches.
Mitigation strategies for CVE-2018-19491 should focus on immediate patching of affected Gnuplot installations to version 5.2.6 or later, which contains the necessary fixes for the buffer overflow condition. System administrators should also implement input validation measures to restrict font parameter lengths and monitor for suspicious plotting activities. The vulnerability's classification under ATT&CK technique T1059.007 for command and scripting interpreter usage suggests that defenders should monitor for unusual command execution patterns when Gnuplot processes user inputs, particularly in automated environments where plotting scripts might be executed. Additional protective measures include restricting file permissions for Gnuplot installations, implementing network segmentation to limit access to systems running Gnuplot, and conducting regular security assessments to identify similar buffer overflow conditions in other plotting or visualization software components that might be similarly vulnerable to the same class of flaws.