CVE-2019-16107: phpBB Cross-Site Request Forgery (CSRF)

Background

phpBB is a popular open-source forum software written in PHP. It provides a platform for users to create and manage online discussion forums. The vulnerability in question affects phpBB version 3.2.7. This version introduced a flaw in the form token validation, which allows for Cross-Site Request Forgery (CSRF) attacks specifically targeting the deletion of post attachments.

Vulnerability Detail

The vulnerability arises from the lack of proper form token validation in phpBB 3.2.7. This oversight enables attackers to craft malicious requests that can trick authenticated users into unknowingly performing actions, such as deleting post attachments, without their consent. CSRF attacks can have various ramifications, including unauthorized data modification, account compromise, and potential data loss. The severity of this vulnerability is considered moderate, with a CVSS score of 4.3.

composer require phpbb/phpbb:3.2.8

Workaround

If upgrading to the latest version is not immediately feasible, a temporary workaround can be implemented by manually validating form tokens in the affected code. This can be achieved by comparing the form token received in the request with the expected token stored in the session. If the tokens do not match, the request should be rejected. Here is an example of how this validation can be performed in PHP:

// Retrieve the form token from the request
$token = $_POST['token'];

// Retrieve the expected token from the session
$expectedToken = $_SESSION['token'];

// Compare the tokens
if ($token !== $expectedToken) {
    // Reject the request
    die('Invalid form token');
}

It is important to note that this workaround is not a permanent solution and should be replaced with the official fix as soon as possible.

Conclusion

In conclusion, phpBB version 3.2.7 is vulnerable to Cross-Site Request Forgery (CSRF) attacks that can lead to the unauthorized deletion of post attachments. To mitigate this vulnerability, it is crucial to upgrade to phpBB version 3.2.8 or later. Alternatively, a temporary workaround can be implemented by manually validating form tokens. For further assistance and support in vulnerability remediation, please contact DevNack.com.

See every vulnerability recorded for phpbb/phpbb →

FAQ