For the third time this month, jailbroken iPhones and iPods are at risk of attack.

"Jailbreaking" allows iPhones and iPods to run software that Apple has not sanctioned and is, according to cybersecurity firm Intego, "extremely dangerous...because of the vulnerabilities that this process creates."

Users of jailbroken devices -- an estimated 6% to 8% of iPhone users -- who have the ssh networking software installed, and have failed to change the default password, may be vulnerable to the newly reported worm.

The worm is called iBotNet.A by Intego. It is called the Duh virus by Sophos, another cybersecurity company.

"Duh is a good name for this virus," said Sophos security researcher Paul Ducklin in a blog post. "It will only infect those who escaped Ikee infection (since those phones would no longer have SSH active for the new virus to break in) but still didn't bother to change their root password away from Apple's feeble default root password of 'alpine'."

The Ikee worm, believed to be the first iPhone worm, was reported in early November. It affected jailbroken devices in Australia by replacing the wallpaper image with a picture of Rick Astley. Shortly thereafter, a tool for hacking jailbroken iPhones was spotted.

Duh will search its local network and several IP address ranges linked to ISPs in Europe for vulnerable iPhones and iPods. When it finds them, it will change the root password and then download malicious files from a server in Lithuania.

According to Intego, those files will turn the infected device into a zombie or bot in a larger network of compromised devices, known as a botnet.

The worm also records information gathered from compromised iPhones, for possible future misuse, and alters a host file, if present, for Dutch online bank ING. The alteration sends would-be ING visitors to a look-alike site that will presumably steal login credentials.

Finding the flaws in your operating systems and applications is only the beginning. You then need to plot a path to security and ensure that no new weaknesses find their way onto your network. This Dark Reading report focuses on how to do that. Download the report here (registration required).