A new Trojan horse masquerading as a video "codec" required to view content on certain Web sites tries to change key settings on the victim's Internet router so that all of the victim's Web traffic is routed through servers controlled by the attackers.
According to researchers contacted by Security Fix, recent versions of the ubiquitous "Zlob" Trojan (also known as DNSChanger) will check to see if the victim uses a wireless or wired hardware router. If so, it tries to guess the password needed to administer the router by consulting a built-in list of default router username/password combinations. If successful, the malware alters the victim's domain name system (DNS) records so that all future traffic passes through the attacker's network first. DNS can be thought of as the Internet's phone book, translating human-friendly names like example.com into numeric addresses that are easier for networking