A new form of phishing that capitalises on the default password settings of wireless routers could allow hackers to steal personal financial details.

Known as “drive-by pharming,” the technique is an advanced version of phishing, where computer passwords stolen by posing as a trustworthy source can allow hackers to take over someone’s connection to the internet without their knowledge, by relying on users not changing their wireless routers’ default security passwords.

Zulfikar Ramzan, from internet security company Symantec said: “I believe this attack has serious widespread implications and could affect many millions of users worldwide. All you have to do to become a victim is simply visit a web page that hosts some malicious code.

“You don’t have to click OK on anything or accidentally download and install malicious software.”

The hacker installs a piece of computer code through the website to change default router passwords and the Domain Name Server (DNS) server settings, potentially redirecting a user to a fraudulent version of their bank account website.

It was not known whether the new form of attack has been used maliciously yet, but the experts who identified it said they had a duty to inform interest users of the risks before it became widespread.

Ramzan said this new type of threats was particularly worrying because they are more silent and invisible, making it more difficult to convey the danger to the public. But he urged users to take the simple precaution of changing their router’s default password to avoid being caught out.