The FBI made a tool to help you determine if you were a victim of the DNSChanger malware.

If you’re like many casual Internet users, you have no idea how to get the information to plug into the input box.

Unfortunately, the security model of most modern browsers makes it impossible to easily retrieve this information. However, it is possible to grab the DNS entries if the user is willing to trust the requesting source.

To help make it easier to determine if you’re infected, I wrote DNSChanger Detector. It’s a small Java applet that requires the user to allow it to have privileged access to the DNS entries via a call to sun.net.dns.ResolverConfiguration to get the nameservers. Once it has them, there is some jQuery glue in place to let Javascript access the results.

I understand why the FBI didn’t attempt to go this route, but it will hopefully be useful to folks who don’t wish to walk their friends and family through the process.