CVE-2023-39273: Critical Integer Overflow Vulnerabilities in GTKWave’s LXT2 facgeometry Parsing Function

Overview

In this blog post, we delve into the critical details of a recently discovered vulnerability, CVE-2023-39273, affecting the LXT2 facgeometry parsing functionality of GTKWave version 3.3.115. This vulnerability is particularly concerning due to its potential to allow arbitrary code execution, which could lead to a full system compromise or data leakage. Because GTKWave is a widely used waveform viewer in the digital design industry, this vulnerability could lead to significant disruptions and security issues if not properly addressed.

Vulnerability Summary

CVE ID: CVE-2023-39273
Severity: High (CVSS 7.8)
Attack Vector: Local
Privileges Required: Low
User Interaction: Required
Impact: Potential system compromise and data leakage

Affected Products

Product | Affected Versions

GTKWave | 3.3.115

How the Exploit Works

The vulnerability resides in the LXT2 facgeometry parsing functionality of GTKWave. It is based on integer overflow vulnerabilities that could occur when allocating the `flags` array. An attacker can craft a malicious .lxt2 file that, when opened by a victim, triggers the integer overflow. This flaw could potentially lead to memory corruption, which in turn could be exploited to execute arbitrary code on the victim’s system.

Conceptual Example Code

Below is a conceptual example of how an attacker might craft a malicious .lxt2 file to exploit this vulnerability:

#include <stdio.h>
#include <stdlib.h>
int main() {
FILE *file;
unsigned long long int large_value = 0xFFFFFFFFFFFFFFFF;
file = fopen("malicious.lxt2", "w");
if (file == NULL) {
printf("Error opening file\n");
return -1;
}
fwrite(&large_value, sizeof(large_value), 1, file);
fclose(file);
return 0;
}

In this simplified example, an attacker crafts a .lxt2 file that contains an exceedingly large integer value. When GTKWave attempts to allocate the `flags` array based on this value, it results in an integer overflow and potential memory corruption.

Recommended Mitigation

Users of the affected GTKWave version are strongly advised to apply the vendor-supplied patch as soon as possible to mitigate this vulnerability. In cases where immediate patching is not possible, employing a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as temporary mitigation, but these should not be considered a long-term solution. As always, caution should be exercised when opening files from unknown sources.