php3 and php Variable Difference

Question

I am working on converting some ancient .php3 code. While running the ancient .php3 version on the ancient box everything works fine. When I click the rewrite button it enters the rewrite if block.

.php3

<?
if($rewrite) {
//here is therewrite code
}

<input class="smButton" type="submit" name="rewrite" value="Save Changes"> 

.php

<?php
if($rewrite) {
//here is therewrite code
}

<input class="smButton" type="submit" name="rewrite" value="Save Changes">

Is there something obvious that I am missing? Something in the .php3 version sets the rewrite variable but in the new version it isn't set unless I manually set it at the top of the .php file.

Hopefully this is enough code. I am just wondering what could cause such different behaviors between the 2 versions.

Answer 1

register_globals is probably on for PHP 3 and off in your newer PHP version (as it should be)

Answer 2

You have to replace the $rewrite by $_POST['rewrite'], because your new PHP version doesn't activate register_globals, which translate every $_POST['x'] and $_GET['x'] (and more generally $_REQUEST['x']) to $x)

This leads to a bunch of security holes, if you have PHP code of low quality (which can be the case if you haven't maintain it since years).