finding vunerabilities

[forcer]

i was checking for vunerabilities on a server to see if i could download mp3 files without them knowing, i was successful. i coded the script below, entered the big long url into a box clicked generate and it told me the actual mp3 link.

for instance a url such as:

www.site.net/downloadMP3.php?tune=666%20-%20Devil%20-%20What%20the%20hell%20mix.mp3& uri=L2hvbWUwL2Rhei9wdWJsaWNfaHRtbC9tcDMvY2hvb25zLw
==&id=979

would be decoded with my script and would shoot out the link:

www.site.net/mp3/choons/666 - Devil - What the hell mix.mp3

i click the link and download the mp3.

and this is the code i used:

<?php 
if ($_GET['url']) { 
    $tstart = strpos($_GET['url'], 'tune=')+5; 
    $tend = strpos($_GET['url'], '&', $tstart); 
    $tune = urldecode(substr($_GET['url'], $tstart, $tend-$tstart)); 
    $ustart = strpos($_GET['url'], 'uri=')+4; 
    $uend = strpos($_GET['url'], '&', $ustart); 
    $uri = base64_decode(substr($_GET['url'], $ustart, $uend-$ustart)); 
    $url = 'http://www.site.net'.substr($uri, 22).$tune; 
    echo "<font size=\"2\" face=\"Arial, Helvetica, sans-serif\"><a href=\"$url\">$url</a></font>"; 
} 
?>

and the test was successful the mp3 downloaded.

but for the second test we used a random number uri. Meaning the download link is:

http://www.site.net/downloadMP3.php?tune=Acida%20-%20Acida.mp3&uri=loCAxc/unOdDIusitlwAAzptpfjpBrwHd&id=195

and when i put that through my script above it shoots out a link like this:

http://www.site.net¼Acida - Acida.mp3

which works, apart from it hides the directory which is mp3/choons/ with ¼

we are still looking for a way around this.

how can this url be decoded and display the correct url. any help or comments highly appreciated

 

[X-Istence]

Well that really is not a vulniribilty. Its more like a way they have coded their script.