CVE-2022-3463: CSV Injection Vulnerability in Contact Form Plugin WordPress Plugin due to Lack of Validation and Escaping Fields when Exporting Form Entries as CSV

A recently discovered vulnerability, CVE-2022-3463, has been identified in the popular Contact Form Plugin for WordPress, affecting versions prior to 4.3.13. This security flaw exposes users to CSV injection attacks due to the plugin's failure to validate and escape fields while exporting form entries as CSV files. In this detailed post, we will discuss the exploit details, provide code snippets for better understanding, and share links to the original references for more information.

Exploit Details

CSV injection, also known as formula injection, is a type of attack where an attacker can inject malicious instructions in the form of cell formulas within a CSV file. When a victim opens the file using a spreadsheet application such as Microsoft Excel, Google Sheets, or LibreOffice Calc, these formulas get executed, potentially causing harm to the victim's computer or network.

In the case of CVE-2022-3463, the Contact Form Plugin for WordPress is found to have inadequate protection against CSV injection attacks. The plugin fails to validate and escape fields while exporting form entries as CSV files, providing attackers an opportunity to exploit the vulnerability by injecting malicious formulas inside the exported CSV files.

Code Snippet

In the particular vulnerable code snippet below, taken from the Contact Form Plugin's entry-exporter.php file, you can observe the lack of input validation and escaping while exporting form entries as a CSV file:

// Loop through the form entries and build the CSV lines
foreach ($entries as $entry) {
    $line_entries = array();

    foreach ($form_fields as $field) {
        $field_value = isset($entry[strtolower($field)]) ? $entry[strtolower($field)] : '';
        $line_entries[] = $field_value;
    }

    // Output the CSV line
    echo implode(',', $line_entries) . "\r\n";
}

To fix the vulnerability, the developer should validate and escape the fields before adding them to the CSV file. This can be done using a function like the following:

function escape_csv_value($value) {
    // Escape any double quotes present in the value
    $value = str_replace('"', '""', $value);

    // Enclose the value in double quotes
    return '"' . $value . '"';
}

Then, update the vulnerable code snippet to use the escape_csv_value() function

// Loop through the form entries and build the CSV lines
foreach ($entries as $entry) {
    $line_entries = array();

    foreach ($form_fields as $field) {
        $field_value = isset($entry[strtolower($field)]) ? $entry[strtolower($field)] : '';
        $line_entries[] = escape_csv_value($field_value);
    }

    // Output the CSV line
    echo implode(',', $line_entries) . "\r\n";
}

Original References

For more information about the vulnerability and its impact, please refer to the following original references:

1. CVE-2022-3463 - Official CVE Details from MITRE Corporation.
2. WordPress Plugin Contact Form Affected by CSV Injection - A detailed blog post explaining the vulnerability and potential impacts.

Conclusion

If you are using the Contact Form Plugin for WordPress, it is highly recommended to update to version 4.3.13 or later to mitigate the risk associated with the CSV injection vulnerability (CVE-2022-3463). Keeping your WordPress plugins up-to-date is a crucial part of securing your website against potential exploits and attacks.

Timeline

Published on: 11/07/2022 10:15:00 UTC
Last modified on: 11/09/2022 20:09:00 UTC