Hacker leaks passwords for more than 500,000 servers, routers, and IoT devices

A hacker has published this week a massive list of Telnet credentials for more than 515,000 servers, home routers, and IoT (Internet of Things) "smart" devices.

The list, which was published on a popular hacking forum, includes each device's IP address, along with a username and password for the Telnet service, a remote access protocol that can be used to control devices over the internet.

According to experts to who ZDNet spoke this week, and a statement from the leaker himself, the list was compiled by scanning the entire internet for devices that were exposing their Telnet port. The hacker than tried using (1) factory-set default usernames and passwords, or (2) custom, but easy-to-guess password combinations. These types of lists -- called "bot lists" -- are a common component of an IoT botnet operation. Hackers scan the internet to build bot lists, and then use them to connect to the devices and install malware.