Advisory: eXpBlog <= 0.3.5 Cross Site Scripting Vulnerabilities Release Date: 10/09/2006 Last Modified: 10/09/2006 Author: Tamriel [tamriel gmx 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=>">... 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