Author: Ameeba

Overview

The CVE-2023-37576 is an alarming vulnerability that exists within the GTKWave 3.3.115, specifically in its VCD get_vartoken realloc functionality. This vulnerability is predominantly characterized by multiple use-after-free vulnerabilities that can be exploited through a specially crafted .vcd file. The exploitation could potentially lead to arbitrary code execution. The vulnerability primarily affects users of the GTKWave software and matters significantly due to its capacity to compromise the system or lead to data leakage.

Vulnerability Summary

CVE ID: CVE-2023-37576
Severity: High – CVSS: 7.8
Attack Vector: File-based
Privileges Required: None
User Interaction: Required (opening 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 leverages a series of use-after-free vulnerabilities present in the VCD get_vartoken realloc functionality of GTKWave 3.3.115. A threat actor can craft a malicious .vcd file that, when opened by the victim, triggers these vulnerabilities. The exploitation of these vulnerabilities can potentially lead to arbitrary code execution, which in turn could result in a total system compromise or leakage of sensitive data.

Conceptual Example Code

The actual exploit code would be specific to the .vcd file format and would require detailed knowledge of GTKWave’s VCD parsing implementation. However, the general concept of a use-after-free exploit can be illustrated as follows:

char *ptr = malloc(10);
free(ptr);
// Time passes and the program continues execution
// The attacker manages to use 'ptr' after it has been freed
strcpy(ptr, "Exploit");

In this simplified example, a memory space is allocated (using ‘malloc’) and then freed (using ‘free’). However, the pointer to that memory space is still accessible later in the program. If an attacker can manipulate the program’s execution to reach this point, they could potentially insert malicious code or data at the location pointed to by ‘ptr’, leading to unexpected behavior or even arbitrary code execution.

Mitigation and Recommendations

The most effective mitigation for this vulnerability is to apply the vendor-supplied patch which fixes the use-after-free vulnerabilities in GTKWave’s VCD parsing code. If a patch cannot be applied immediately, temporary mitigation can be achieved by using a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to block or detect attempted exploits.
In addition to these specific measures, it is always good practice to be cautious when opening files from unknown or untrusted sources. It is especially important to be wary of .vcd files, as these are the vector through which the CVE-2023-37576 vulnerability is exploited.

Overview

In this post, we will be examining the CVE-2023-37575 vulnerability-a series of use-after-free vulnerabilities found in the VCD get_vartoken realloc functionality of GTKWave 3.3.115. This vulnerability is notable due to its ability to allow an attacker to execute arbitrary code on a system. The exploitation of this vulnerability requires a victim to open a maliciously crafted .vcd file, making it a potential threat to users and systems that handle .vcd files.
This vulnerability is significant not only because of the potential damage it can cause, but also because of its relative simplicity; it requires only user interaction for successful execution, making it a dangerous vector for attacks aiming to compromise systems or leak sensitive data.

Vulnerability Summary

CVE ID: CVE-2023-37575
Severity: High (CVSS: 7.8)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: Potential system compromise and data leakage

Affected Products

Product | Affected Versions

GTKWave | 3.3.115

How the Exploit Works

The use-after-free vulnerabilities in the VCD get_vartoken realloc functionality of GTKWave 3.3.115 occur when the software uses a pointer after the system has freed the memory it points to. When a victim opens a specially crafted .vcd file, an attacker can manipulate the memory allocation to execute arbitrary code. This code execution can lead to a system compromise or potential data leakage, depending on the attacker’s intent.

Conceptual Example Code

Below is a conceptual example of how the vulnerability might be exploited. In this case, the attacker creates a malicious .vcd file that triggers the use-after-free vulnerability when opened.

# Pseudocode
Create malicious_vcd_file.vcd
{
Manipulate memory allocation via get_vartoken realloc function
Inject arbitrary malicious code
}
Send malicious_vcd_file.vcd to victim
{
Victim opens malicious_vcd_file.vcd
Arbitrary malicious code executes leading to potential system compromise or data leakage
}

Please note that this is a conceptual example and may not reflect the exact method an attacker might use to exploit this vulnerability. It is intended to illustrate the basic principle of the exploit and should not be used for malicious purposes.

Mitigation Guidance

To mitigate the risks associated with the CVE-2023-37575 vulnerability, users and administrators are advised to apply vendor patches as soon as they become available. In the absence of a patch, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as a temporary mitigation measure. These measures can protect against the arbitrary code execution that forms the basis of the exploit. However, they should serve only as an interim solution until a more permanent fix can be applied.

Overview

The CVE-2023-37574 is a critical vulnerability that affects GTKWave 3.3.115, a fully featured GTK+ based wave viewer. The vulnerability pertains to a use-after-free flaw in the VCD get_vartoken realloc functionality of the software. If exploited successfully, it can lead to arbitrary code execution, potentially compromising the system and leading to data leakage. This vulnerability is especially concerning as it can be triggered simply by opening a malicious .vcd file, making it a high-risk issue for users who frequently handle .vcd files.

Vulnerability Summary

CVE ID: CVE-2023-37574
Severity: High (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 exploit takes advantage of a use-after-free vulnerability present in the VCD get_vartoken realloc functionality of GTKWave 3.3.115. By crafting a malicious .vcd file, an attacker can trigger this vulnerability. When the file is opened, the software attempts to read the file. During the file parsing process, due to the aforementioned vulnerability, previously freed memory spaces are reaccessed, leading to a state of memory corruption. This state can then be exploited by the attacker to execute arbitrary code, compromising the system.

Conceptual Example Code

Here is a conceptual example of how a malicious .vcd file might look. This is not a real exploit, but a simplified representation to illustrate the concept.

$timescale 1 ns $end
$var wire 1 ! clk $end
$var wire 64 # data $end
$var wire 1 $ en $end
$var wire 1 % rd_wr $end
$var wire 1 & irq $end
$upscope $end
$enddefinitions $end
#0
$dumpvars
0!
bxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx #
0$
0%
0&
$end

Overview

In this blog post, we will examine the CVE-2023-37573 vulnerability, a serious security flaw that affects GTKWave 3.3.115. This vulnerability is significant due to its potential to lead to arbitrary code execution when a specially crafted .vcd file is opened. The vulnerability is triggered by the GUI’s recoder VCD parsing code, and it’s particularly concerning for users of this version of GTKWave as it could potentially lead to system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2023-37573
Severity: High (7.8)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: System compromise, data leakage

Affected Products

Product | Affected Versions

GTKWave | 3.3.115

How the Exploit Works

The vulnerability lies in the get_vartoken realloc function of GTKWave 3.3.115. The function is responsible for reallocating memory resources during the parsing of .vcd files. However, the function maintains a reference to a memory location even after it has been freed, leading to a use-after-free vulnerability.
When a specially crafted .vcd file is opened, the function can be manipulated to reference this deallocated memory space. This manipulation can lead to arbitrary code execution as the malicious code inserted in this space gets executed.

Conceptual Example Code

While we don’t encourage or condone malicious activities, a conceptual example of this vulnerability might look something like this:

#include<stdio.h>
#include<stdlib.h>
int main() {
// Allocate memory
char *ptr = malloc(8);
// Use memory
strcpy(ptr, "GTKWave");
// Free memory
free(ptr);
// Here's where the use-after-free vulnerability is created.
// We're using 'ptr' after it has been freed.
strcpy(ptr, "Malicious code");
return 0;
}

In this conceptual example, the malicious code could be anything, from a payload that creates a backdoor to one that leaks sensitive data.

Mitigation

The most effective way to rectify this vulnerability is to apply the vendor patch once it becomes available. Until then, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can offer temporary mitigation. Users are also advised to avoid opening .vcd files from untrusted sources.