Online attacks launched from thousands of connected devices, such as one that disabled parts of the internet in October, are here to stay, the Federal Bureau of Investigation is warning.

“The exploitation of the ’Internet of Things’ (IOT) to conduct small-to-large scale attacks on the private industry will very likely continue,” the FBI wrote in an Oct. 26 bulletin to private companies. A person familiar with the matter said a version of the bulletin that appeared on the internet Friday was authentic.

In...