Fake a $_POST via PHP

Question

I'm all in a security funk right now so I'm going through making everything as secure as possible. I got a login going and I'm referencing this:

http://www.addedbytes.com/writing-secure-php/writing-secure-php-1/

The first example is that of a login and if you say ?authorization=1 you get in. But if I wrap my code around a if($_POST) then the user MUST make a post. Can a user fake a $_POST? How do I go about faking a $_POST?

Answer 1

A user can simply create a file on their local machine with:

<form action="http://yoursite.com/login.php" method="post">
    <input type="text" name="username"  value="hahaha faked it!" />
    <input type="text" name="password" value="hee hee you can't tell this is fake" />
    <input type="submit">
</form>

and boom, "fake" post. In other words, you have to assume that anything and everything the user sends is potentially fake.