Description

Detects when sensitive user input data is being stored unsafely in files using PHP file operations. This creates a security risk as sensitive user data like passwords or personal information could be written to files without proper encryption or access controls.

Detection Strategy

• Identifies PHP file write operations (like fwrite, fputs) that store data to files

• Checks if the file handle comes from an unsafe file open operation (e.g. fopen)

• Verifies that the data being written originates from user input (e.g. $_POST, $_GET)

• Triggers when both conditions are met - unsafe file operations with user input data

Vulnerable code example

<?php
function unsafe_write_sensitive_data() {
    $fp = fopen('/var/data/users.txt', 'w');
    $password = $_POST['password'];  // Insecure: Directly using unvalidated user input
    fwrite($fp, $password);         // Vulnerable: Writing unsanitized password to file
    fclose($fp);
}

✅ Secure code example

<?php
function safe_write_sensitive_data() {
    try {
        // Use proper error handling for file operations
        if (!$fp = fopen('/var/data/users.txt', 'w')) {
            throw new Exception('Failed to open file');
        }
        ...