Cybercriminals to hack home routers to attack online banking users

According to researchers from the Polish Computer Emergency Response Team (CERT Polska), attackers will likely target users from other countries as well in the future using similar techniques.

Unless intentionally configured otherwise, devices connected to a local network will typically use the DNS server provided by the networks router to resolve domain names to IP (Internet Protocol) addresses. If attackers compromise the router and configure it to use a DNS server under their control, they can respond with rogue IP addresses to DNS queries for the domain names they wish to target.

In the recent attacks in Poland, the hackers used a DNS server that responded with rogue IP addresses for the domain names of five Polish banks. Those IP addresses corresponded to a server that acted as a proxy, providing attackers with a man-in-the-middle position to intercept, inspect and modify traffic between users and the online banking websites they wanted to target.

The problem for the hackers was that those websites used HTTPS - HTTP with SSL encryption -making it impossible to impersonate them without a valid digital certificate issued by a certificate authority. Because of this, they decided to use a less sophisticated technique known as SSL stripping.

Many banks use SSL encryption for their online banking systems, but not their entire websites. In most cases, users first connect to the banks main website over plain HTTP and then click on a button or link to access the log-in page for the secure part of the site where SSL is enabled.