Proofpoint security researchers claim internet-enabled household appliances are already being programmed to send out spam emails by hackers.
Researchers have uncovered evidence that hackers have launched cyber attacks on household smart devices.
IT security firm Proofpoint said smart devices, such as internet-enabled fridges and smart TVs, have been used to send out 750,000 spam emails between 23 December and 6 January.
The firm said as the number of connected devices increases, the proof of an "Internet of Things"-based attack taking place “has significant security implications for device owners and Enterprise targets.”
Proofpoint said criminal gangs have begun to hijack home routers, smart appliances and other components of the Internet of Things and transform them into "thingbots" to carry out similar malicious activity to botnets.
It said these devices give criminals a “target-rich environment” and poorly protected internet-connected devices may be more attractive and easier to infect than traditional PCs, laptops, and tablets.
"Botnets are already a major security concern, and the emergence of thingbots may make the situation much worse," said Proofpoint security manager Dave Knight.
"Many of these devices are poorly protected at best and consumers have virtually no way to detect or fix infections when they do occur. Enterprises may find distributed attacks increasing as more and more of these devices come online and attackers find additional ways to exploit them,” he said.
Michael Osterman, principal analyst at Osterman Research, said this attack heralded a new chapter in cyber security.
"The Internet of Things holds great promise for enabling control of all the gadgets that we use on a daily basis," he said.
"It also holds great promise for cyber criminals who can use our homes' routers, televisions, refrigerators and other internet-connected devices to launch large and distributed attacks."