In this post, we're going to dive into a recently discovered security vulnerability affecting the popular Quiz and Survey Master plugin for WordPress. The plugin, which is used by many website administrators to create quizzes and surveys, has been found to be vulnerable to an input validation bypass vulnerability (CVE-2022-4033), which affects versions up to, and including, 8..4.

In the following sections, we will provide a detailed breakdown of the exploit, describe how to reproduce the vulnerability and explore potential implications for affected WordPress sites. Additionally, we'll provide links to the original references and resources for further reading.

Exploit Details

The CVE-2022-4033 vulnerability stems from insufficient input validation on the 'question[id]' parameter within the Quiz and Survey Master plugin. This input validation bypass allows attackers to inject content other than the specified value (i.e. a number, file path, etc.), making it possible for them to submit values other than the intended input type.

The exploit involves submitting unexpected input data, such as text strings or file paths, to the 'question[id]' parameter. Without proper validation in place, the plugin may erroneously accept this input, leading to potential security issues, including data leakage or unauthorized access.

To demonstrate the vulnerability, consider the following example code snippet

// The vulnerable code in the Quiz and Survey Master plugin
if ( is_numeric( $_POST["mlw_question" . $x] ) ) {
    $question_id = $_POST["mlw_question" . $x];
} else {
    // Incorrect input validation
    $question_id = "some input that should not be allowed";
}

Here, the developer intended to only allow numeric inputs for the question_id parameter by using the is_numeric() function. However, an attacker could potentially bypass this validation check by submitting a value like "1; SELECT * FROM users;", which could lead to undesirable consequences such as SQL injection, if the input is not properly sanitized elsewhere in the code.

For full details on the CVE-2022-4033 vulnerability, you can refer to the following resources

1. CVE-2022-4033 - Official CVE Details
2. Quiz and Survey Master Plugin Homepage

Mitigation Steps

If you're using the Quiz and Survey Master plugin on your WordPress site, it's crucial to take action to mitigate the impact of this vulnerability. The plugin's developers released a patch in version 8..5 that addresses the CVE-2022-4033 vulnerability. As such, administrators should promptly update their plugin to the latest available version to protect their site from potential attacks. Additionally, be sure to routinely update your WordPress plugins and core installation to minimize the risk of other vulnerabilities.

Conclusion

The CVE-2022-4033 input validation bypass vulnerability in the Quiz and Survey Master plugin for WordPress serves as an essential reminder to always practice proper input validation and sanitation in web applications. Failure to do so can leave your site open to potential security threats. By staying informed about the latest threats and keeping your site up-to-date, you can better protect your WordPress site from harmful attacks.

Timeline

Published on: 11/29/2022 21:15:00 UTC
Last modified on: 12/01/2022 22:12:00 UTC