eXpBlog-0.3.5.txt

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Advisory: eXpBlog <= 0.3.5 Cross Site Scripting Vulnerabilities  
Release Date: 10/09/2006  
Last Modified: 10/09/2006  
Author: Tamriel [tamriel <at> gmx <dot> net]  
Application: eXpBlog <= 0.3.5  
Risk: Low  
Vendor Status: contaced | replied  
Vendor Site: www.expblog.de  
  
  
Overview:  
  
Quote from www.expblog.de:  
  
"Das eXpBlog ist eine beliebte Freeware weBlog Software basierend  
auf PHP und mySQL. Mit einem eXpBlog verfuegen Sie ueber ein  
flexibles und schnelles Mehrbenutzer-weBlog welches durch ein  
Plugin-System komfortabel erweiterbar ist."  
  
There are some cross site scripting vulnerabilities which can  
be exploited by malicious people to conduct script insertion attacks.  
  
The vulnerability has been discovered in the latest version. Other  
versions may also be affected.  
  
  
Details:  
  
1) Cross Site Scripting Vulnerability in kalender.php  
  
Arround the lines 130-140 the variable `$_SERVER['PHP_SELF']` is  
not properly sanitised before being used. This can be exploited  
to insert arbitrary HTML and script code, which is executed in a  
user's browser session in context of an affected site when the  
malicious data is viewed.  
  
2) Cross Site Scripting Vulnerability in pre_details.php  
  
Arround the lines 15-20 the variable  
`$_POST["captcha_session_code"]` is not properly sanitised before  
being used. This variable is used in the details.php arround  
line 152, here an attacker can insert malicious code. The  
captcha class may be affected too, because you can let it open a  
special file (captcha_class.php, arround line 140).  
  
  
Proof of Concept:  
  
1) details.php/%3E%22%3E%3Cscript%3Ealert('Unsecure')%3C/script%3E  
  
2) comment=1&captcha_session_code=>"><script>alert('hole')</script>...  
  
  
Solution/Fix:  
  
Edit the source code to ensure that input is properly sanitised.  
Use functions like PHP`s htmlentities() function.  
  
Disclosure Timeline:  
  
10/03/2006 - Discovery of the vulnerabilities  
10/03/2006 - Contacted the vendor  
10/04/2006 - Vendor reponse  
10/09/2006 - Supplied bugfix to the official forum  
10/09/2006 - Public disclosure  
  
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