Examples of vulnerable PHP code? [closed]

Answer 1

Check out the Open Web Application Security Project. They have explanations and examples of lots of different kinds of attacks. http://www.owasp.org/index.php/Category:Attack

Answer 2

Another example of a sql-injection-vulnerable login script. This is unfortunately very common among new programmers.

$username = $_POST["username"];
$password = $_POST["password"];
$query = "SELECT username, password 
          FROM users 
          WHERE (username = '{$username}') 
            AND (password = '{$password}')";

Answer 3

A really common beginner's mistake is forget to terminate script execution after a redirect.

<?php
if ($_SESSION['user_logged_in'] !== true) {
    header('Location: /login.php');
}

omg_important_private_functionality_here();

The solution:

if ($_SESSION['user_logged_in'] !== true) {
    header('Location: /login.php');
    exit();
}

This can be missed when testing in a normal browser, because browsers usually follow the Location header without rendering any of the output of the script.

Answer 4

The WRONG way to do templates.

<?php

  include("header.php");
  include($_GET["source"]); //http://www.mysite.com/page.php?source=index.php
  include("footer.php");

?>