ppp-design found the following authentication bypass vulnerability in Blahz-DNS:


Details

Product: Blahz-DNS
Affected Version: 0.2 and maybe all versions before
Immune Version: 0.25
OS affected: OS independent (php/mysql)
Vendor-URL: http://blahzdns.sourceforge.net
Vendor-Status: informed, new version avaiable
Security-Risk: very high
Remote-Exploit: Yes


Introduction

Blahz-DNS is PHP/MySQL based DNS (BIND 9) administration with support for primary and secondary zones, user authentication, User and Admin account types, and restricted access for user accounts to certain primary and secondary zones. Unfortunately the security concept is broken by design. One can easily access any page different to login.php without any proper password.


More details

The software is using a very poor security concept: The user is only asked for a valid user password combination at the login page. Access to any other page is granted without any password.


Proof-of-concept

At http://www.example.com/dostuff.php?action=modify_user a blackhat can change existing users (eg. changing passwords) or add new users without beeing authorized.


Temporary-Fix

Use apache's .htpasswd to temporary restrict access to blahzdns.


Fix

Use at least version 0.25.


Security-Risk

A blackhat can easily manipulate DNS entries remotly without being authorized in any way. This often is the first step of a hacking scenario. Therefore we are rating the security risk to very high.


Vendor status

The author has reacted very fast and published a new version in less than 12 hours. All users are encouraged to upgrade.


Disclaimer

All information that can be found in this advisory is believed to be true, but maybe it is not. ppp-design can not be held responsible for the use or missuse of this information. Redistribution of this text is only permitted if the text has not been altered and the original author ppp-design (http://www.ppp-design.de) is mentioned.