GNUCITIZEN

This article is a continuation of the following GNUCITIZEN articles, which include an introduction to the topic and also some initial observations: Hacking Linksys IP Cameras (pt 1), Hacking Linksys IP Cameras (pt 2).

Unlike the previous two vulnerabilities I released, the vulnerabilities I’m releasing in this post are perhaps not so useful to break into the device as you need access to the admin account to exploit them. [...]

During the easter break, I was playing with my my wireless Linksys IP camera which, although I bought several months ago, I hadn’t taken my time to give the attention this beauty deserves until now! :)

The model in particular is the WVC54GCA, which I would say is one of the most affordable Wi-Fi IP cameras out there (about GBP 80 in the UK), making it a great toy to tinker with. [...]

A device that is vulnerable to this issue, only performs an authentication check (i.e.: is the password being submitted with a request via basic authentication?) when the request is performed using a certain HTTP method. For instance, most devices have a feature to backup the config file which contains all the configuration settings including admin credentials.

Usually, when accessing a web interface of an appliance, the user is prompted to enter a password if not authenticated already. This could be done via a HTML form on the login page or a basic HTTP authentication prompt (among other methods).

Let’s call the authentication stage: A. Once, the admin user enters a username/password combination, the device checks the provided combination against credentials stored in its internal configuration. [...]

Finding authentication bypass bugs is an obvious choice for attackers, since such bugs allow administrative changes to be made without knowledge of the admin password. In other words, compromising the target device without requiring a password is of course something attackers are interested in! You bet! [...]