How can PHP code input in a form be detected and prevented?

To detect and prevent PHP code input in a form, you can use input validation to check for any suspicious characters or keywords commonly used in PHP code. Additionally, you can sanitize the input by removing any potentially harmful code. One way to prevent PHP code injection is by using htmlspecialchars() function to escape special characters. 

// Input validation to prevent PHP code injection
$user_input = $_POST['user_input']; // Assuming user input comes from a form

if (preg_match("/<\?php|eval\(|system\(|shell_exec\(|passthru\(|exec\(/i", $user_input)) {
    // Detected PHP code, handle accordingly (e.g. log the attempt, reject the input)
    echo "Invalid input detected";
} else {
    // Sanitize the input to prevent PHP code injection
    $safe_input = htmlspecialchars($user_input, ENT_QUOTES);
    // Use $safe_input in your application
}

Keywords

PHP form input security validation filtering

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