Midnight Research Labs has just published a new tool. Depant will scan your network and check to see if services are using default passwords. It starts by performing an Nmap scan to discover available services on the network. It organizes these services by speed of response. Using Hydra it does brute force password checking of these services with a default password list. The user can supply an alternate list for the first phase or an additional list to be used in a followup check. Depant has many different options for configuring your scan and will certainly help you find that rogue piece of hardware on your network that someone failed to set up securely.
The Zlob trojan, also known as DNSChanger, has been around for a few years, but recent Zlob variants to appear in the wild attempt to log into routers using a list of default admin/password combos. If they succeed, they alter the DNS records on the router to reroute traffic through the attacker’s server.
Our friend [Dan Kaminisky] recently did a presentation warning against vulnerabilities in internet browser plugins that allow attackers to mount DNS rebinding attacks against routers with default passwords.. Though it achieves the same end, Zlob is different because it infects by the tried-and-true method of fooling users into downloading it inside a fake video codec. Once it is running on a client machine, it is free to attempt to use the default admin id and password of the router to log in and alter DNS settings. It even supports the DD-WRT firmware.
Even if a system is wiped clean of Zlob trojans, the router could still be compromised. The good news is that it is easy to fix and even easier to prevent. Fixing it takes no more than wiping all network clients clean, then resetting the router and restoring custom settings. Prevention is a simple matter of changing the router’s password.