A recently identified vulnerability in Fortinet FortiNAC, CVE-2023-33300, has been discovered that concerns an improper neutralization of special elements used in commands, commonly known as command injection. This vulnerability affects multiple versions of Fortinet FortiNAC, specifically including 7.2.1 and earlier, as well as 9.4.3 and earlier. The vulnerability can potentially allow an attacker to gain unauthorized file access using a specifically crafted request via the inter-server communication port. In this article, we'll dive into the technical details of the exploit, understand its implications, and provide coding examples to visualize the threat in action.

Exploit Technical Details

This security vulnerability occurs due to an oversight in the sanitization of user input. As a result, an attacker can bypass input validation methods by crafting a special payload, which then injects malicious code into the system's command interface. Once executed, the attacker can obtain unauthorized file access within the system.

To give you a better understanding of this vulnerability, let's look at a code snippet analysis, as well as the original references related to CVE-2023-33300.

Let's consider the following simple code that accepts unsanitized input

import subprocess

user_input = input("Enter the file name: ")

cmd = "cat " + user_input
result = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE).stdout.read()

print("Output:\n", result.decode())

In a normal scenario, users will enter a file name, and the "cat" command will display its content. However, the vulnerability lies in the fact that the code doesn't filter or sanitize the user input. This allows the attacker to inject commands, granting them unauthorized file access.

For example, the attacker could enter the following payload

file.txt; ls /etc

The resulting command becomes

cat file.txt; ls /etc

Now, the attacker not only sees the content of "file.txt" but also the directory listing of "/etc." This example highlights a simple scenario where an attacker can manipulate user input to carry out malicious activities.

Original References

The vulnerability CVE-2023-33300 was initially reported by NVD (National Vulnerability Database). The original references to the vulnerability can be found in the following links:

- NVD CVE-2023-33300: https://nvd.nist.gov/vuln/detail/CVE-2023-33300
- FortiGuard Labs Advisory FG-IR-21-024: https://www.fortiguard.com/psirt/FG-IR-21-024

Mitigation and Protection

Fortinet has released patches addressing this vulnerability. It is highly recommended that users update their Fortinet FortiNAC to the most recent version, or at the very least, apply the specific patches mentioned in the aforementioned FortiGuard Labs advisory.

In addition, security best practices also encourage developers to consistently sanitize user inputs within their code. This can help prevent the exploitation of command injection vulnerabilities in your environment.

Conclusion

Command injection vulnerabilities are a prevalent security risk that can lead to unauthorized system access and potential data breaches. Properly sanitizing user input throughout your applications and systems is a fundamental aspect of ensuring that you maintain a secure environment. It is also crucial to stay up to date with recent security patches and updates, especially when concerning devices like Fortinet FortiNAC, which serve as linchpins within many network infrastructure deployments.

To learn more about the details of the CVE-2023-33300 vulnerability and recommended mitigation strategies, please refer to the links in the Original References section above.

Timeline

Published on: 03/14/2025 16:15:27 UTC