The Federal Bureau of Investigation (FBI) has recommended businesses and individuals worldwide to reboot the routers at office or home to counter a malware known as "VPNFilter" that is spreading fast.
The malware affects routers and collect users' information or shut down network traffic.
According to a FBI statement, foreign cyber actors have compromised hundreds of thousands of home and office routers and other networked devices worldwide.
The actors used "VPNFilter" malware to target small office and home office routers.
"The FBI recommends any owner of small office and home office routers power cycle (reboot) the devices," the FBI said on Tuesday.
The malware targets routers produced by several manufacturers and network-attached storage devices by at least one manufacturer. The initial infection vector for this malware is currently unknown.
"VPNFilter is able to render small office and home office routers inoperable. The malware can potentially also collect information passing through the router. Detection and analysis of the malware's network activity is complicated by its use of encryption and misattributable networks," the FBI said.
The FBI recommended people to reboot the routers to temporarily disrupt the malware and aid the potential identification of infected devices.
"Owners are advised to consider disabling remote management settings on devices and secure with strong passwords and encryption when enabled. Network devices should be upgraded to the latest available versions of firmware," the US agency noted.
Earlier, Iran's Computer Emergency Response Team Coordination Centre issued a warning about the fast-spreading malware attack.
The attack is not limited to Iran and has impacted many computer users across the world, the centre warned.
It said it has advised the owners of many brands of routers to turn them off and on again, and download updates from the manufacturer to protect themselves.
The malware was initially detected by Cisco Systems Inc.