Author: Ameeba

Overview

In this blog post, we will delve into the details of a serious cybersecurity vulnerability, CVE-2023-35955, that affects the GTKWave 3.3.115. This vulnerability is particularly significant due to its potential to lead to arbitrary code execution, resulting in potential system compromise or data leakage. The severity of the issue is further underscored by its CVSS Severity Score of 7.8. The vulnerability specifically originates from multiple heap-based buffer overflow vulnerabilities in the fstReaderIterBlocks2 VCDATA parsing functionality of the software.

Vulnerability Summary

CVE ID: CVE-2023-35955
Severity: High (7.8/10)
Attack Vector: File-based (via a specially-crafted .fst file)
Privileges Required: None
User Interaction: Required (victim needs to open a malicious file)
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

GTKWave | 3.3.115

How the Exploit Works

The exploit takes advantage of multiple heap-based buffer overflow vulnerabilities in the fstReaderIterBlocks2 VCDATA parsing functionality of GTKWave. Specifically, the decompression function `LZ4_decompress_safe_partial` is implicated in this vulnerability.
An attacker prepares a specially-crafted .fst file that is designed to trigger these vulnerabilities when opened. The file can be disseminated to victims through various methods, such as phishing emails or malicious downloads. Once the victim opens the malicious file, the attacker can achieve arbitrary code execution, potentially leading to system compromise or data leakage.

Conceptual Example Code

While we won’t provide an actual exploit code for ethical reasons, we can conceptualize the exploitation process.
First, an attacker would need to craft a malicious .fst file that could exploit the buffer overflow vulnerabilities. The payload of this file might look something like this:

$ echo -e "VCD2\n\$end\n\$timescale 1 ns\n\$end\n\$scope module top\n\$end\n\$var wire 1 ! clk\n\$end\n#0\n1!\n#1\n0!\n#2\n1!\n#2.5\n\$dumpvars\n0!\n\$end\n#3\n1!\n#4\n" > malicious.fst

The attacker then disseminates this file to the victim, who, upon opening it with GTKWave, triggers the buffer overflow and subsequent arbitrary code execution.

Mitigation

As a mitigation measure, users can apply the vendor-provided patch to fix this vulnerability. Alternatively, users can deploy Web Application Firewalls (WAF) or Intrusion Detection Systems (IDS) as a temporary mitigation method until the patch can be applied. Regularly updating software and keeping abreast of newly discovered vulnerabilities can help prevent such attacks.

Overview

The cybersecurity landscape is constantly evolving, with new vulnerabilities being discovered on a regular basis. One such vulnerability is the CVE-2023-35704, a serious security flaw identified in the GTKWave 3.3.115. This vulnerability is particularly concerning as it affects the FST LEB128 varint functionality of GTKWave, a widely used waveform viewer for Verilog RTL simulation.
The flaw is significant due to its potential to enable an attacker to execute arbitrary code, leading to full system compromise or potential data leakage. This could have severe implications for users, particularly those in industries where data security is paramount. As such, understanding this vulnerability and how to mitigate its risks is of the utmost importance.

Vulnerability Summary

CVE ID: CVE-2023-35704
Severity: High (7.8 CVSS Score)
Attack Vector: File-based (via a specially crafted .fst file)
Privileges Required: None
User Interaction: Required (victim needs to open the malicious file)
Impact: Arbitrary code execution leading to system compromise or data leakage

Affected Products

Product | Affected Versions

GTKWave | 3.3.115

How the Exploit Works

The exploit takes advantage of multiple stack-based buffer overflow vulnerabilities in the FST LEB128 varint functionality of GTKWave 3.3.115. An attacker crafts a malicious .fst file which, when opened by the victim, overflows the buffer, allowing the attacker to execute arbitrary code on the victim’s system. This is achieved through the manipulation of the fstReaderVarint32WithSkip function, which fails to properly handle specially crafted .fst files.

Conceptual Example Code

Here’s a conceptual example of how the vulnerability might be exploited. This is a simplified representation and actual exploit code may be more complex.

#include <stdio.h>
#include <string.h>
void malicious_fst_file() {
char buffer[10];
// a crafted .fst file with contents exceeding the buffer size
char *malicious_fst = "Exceedingly_long_and_malicious_file_content...";
strcpy(buffer, malicious_fst);
}
int main() {
malicious_fst_file();
return 0;
}

In this example, the `malicious_fst` string represents the malicious .fst file. When the `malicious_fst_file` function is executed, the buffer overflows due to the excessive length of the malicious .fst file, potentially leading to arbitrary code execution.

Mitigation Guidance

As a preventive measure, users are advised to apply the vendor patch as soon as it is available. This patch will fix the vulnerabilities present in the FST LEB128 varint functionality of GTKWave 3.3.115. In the interim, using a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can serve as temporary mitigation, providing some level of protection against potential attacks exploiting this vulnerability.

Overview

In the ever-evolving landscape of cyber threats, a new vulnerability has been discovered in GTKWave 3.3.115, a software used for viewing waveform data. Designated as CVE-2023-35703, this vulnerability, if exploited, can lead to arbitrary code execution, potentially compromising systems and leading to data leakage. This vulnerability specifically affects the FST LEB128 varint functionality of GTKWave. As such, any organization or individual using affected versions of this software could be at risk, making it crucial to understand and address this threat.

Vulnerability Summary

CVE ID: CVE-2023-35703
Severity: High (7.8)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: Arbitrary code execution, potential system compromise, and data leakage

Affected Products

Product | Affected Versions

GTKWave | 3.3.115

How the Exploit Works

The vulnerability lies in the FST LEB128 varint functionality of the GTKWave 3.3.115. Specifically, the vulnerability arises from multiple stack-based buffer overflow vulnerabilities within the fstReaderVarint64 function. To exploit this vulnerability, an attacker would need to craft a malicious .fst file, which, when opened by a victim, could allow the attacker to execute arbitrary code. This could potentially compromise the victim’s system and lead to data leakage.

Conceptual Example Code

Given the nature of this vulnerability, a potential exploit could look something like this:

#include <stdio.h>
#include <string.h>
void vulnerable_function(char *str) {
char buffer[10];
strcpy(buffer, str);
}
int main(int argc, char **argv) {
vulnerable_function(argv[1]);
return 0;
}

In this hypothetical scenario, a buffer overflow occurs when the `vulnerable_function` copies the input string to the `buffer` without checking its size. If the input string is larger than the `buffer`, it would overwrite the adjacent memory, causing a buffer overflow and paving the way for arbitrary code execution.

Mitigation Guidance

Users are advised to apply the vendor patch as soon as possible to mitigate the vulnerability. In the interim, users can use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as a temporary mitigation. Regularly updating and monitoring systems for any unusual activities can also prevent potential exploitation.

Overview

In the realm of cybersecurity, it is crucial to stay ahead of potential threats. A new vulnerability, identified as CVE-2023-35702, has emerged that poses a significant threat to systems running GTKWave 3.3.115. GTKWave is a fully featured GTK+ based wave viewer primarily intended for use with electronics design automation (EDA) simulation software. The vulnerability lies within the FST LEB128 varint functionality of GTKWave, which if exploited, could lead to arbitrary code execution.
This vulnerability matters because it has the potential to compromise systems or leak sensitive data. This becomes particularly dangerous when considering that a victim would only need to open a malicious .fst file to trigger the vulnerability. Hence, it is of utmost importance for system administrators and users to understand the risks associated with this vulnerability.

Vulnerability Summary

CVE ID: CVE-2023-35702
Severity: High (7.8)
Attack Vector: Local
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 exists due to a buffer overflow error within the ‘fstReaderVarint32’ function in the FST LEB128 varint functionality of GTKWave. An attacker can exploit this by crafting a malicious .fst file designed to overflow the buffer, leading to arbitrary code execution.
A buffer overflow occurs when more data is written to a block of memory, or buffer, than it is designed to hold. This extra data overflows into adjacent memory, potentially overwriting and corrupting valuable data or leading to arbitrary code execution.

Conceptual Example Code

Here is a conceptual example of how the vulnerability might be exploited. This is an example of a malicious .fst file that could potentially exploit the buffer overflow vulnerability:
“`shell
# This is a conceptual example and should not be used for malicious purposes
$ echo -e “\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90

Overview

The Common Vulnerabilities and Exposures system has recently identified a significant security vulnerability, CVE-2023-34436, within GTKWave 3.3.115’s LXT2 num_time_table_entries functionality. This out-of-bounds write vulnerability affects a broad range of systems and applications that utilize the GTKWave waveform viewer. It’s of particular concern due to its potential for arbitrary code execution when a malicious .lxt2 file is opened, leading to potential system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2023-34436
Severity: High (7.8 CVSS Score)
Attack Vector: Local file
Privileges Required: User
User Interaction: Required
Impact: Arbitrary code execution, potential system compromise, and data leakage.

Affected Products

Product | Affected Versions

GTKWave | 3.3.115

How the Exploit Works

The exploit capitalizes on an out-of-bounds write vulnerability in the LXT2 num_time_table_entries functionality of GTKWave 3.3.115. An attacker creates a specially crafted .lxt2 file that, when opened by a victim, triggers the vulnerability leading to arbitrary code execution. This vulnerability is particularly dangerous as it can lead to a complete system compromise or data leakage if successfully exploited.

Conceptual Example Code

Below is a conceptual example of how a specially crafted .lxt2 file might look. Note that this is purely hypothetical and not actual exploit code.

#include<stdio.h>
#include<string.h>
int main() {
char buffer[10];
FILE *fp;
fp = fopen(".lxt2", "w");
memset(buffer, 'A', sizeof(buffer)-1);
fwrite(buffer, sizeof(char), sizeof(buffer), fp);
fclose(fp);
return(0);
}

In the above example, the buffer is filled with ‘A’s before being written into a .lxt2 file. This could overflow the num_time_table_entries functionality of GTKWave, triggering the vulnerability.

Mitigation

All users are strongly urged to apply the vendor-provided patch once it becomes available. As a temporary mitigation, users can use a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to prevent the opening of potentially malicious .lxt2 files. It’s also advisable to exercise caution when handling .lxt2 files, especially those received from untrusted sources.