A British government spokesman called the global campaign of cyberespionage "yet another example of Russia's disregard for worldwide norms and global order".
The unusual public warning from the White House, US agencies and Britain's National Cyber Security Center follows a years-long effort to monitor the threat.
The joint statement said that the main targets have been government departments, big companies, firms running 'critical infrastructure, ' and ISPs.
It was the two countries' first such joint alert.
"We have high confidence that Russian Federation has carried out a coordinated campaign to gain access to enterprise, small office, home office routers known as SOHO routers and residential routers, and the switches and connectors worldwide", said Rob Joyce, special assistant to the President and cybersecurity coordinator at the White House, speaking to journalists.
"We don't have full insight into the scope of the compromise", said Jeanette Manfra, a cybersecurity official for the DHS.
The warning is unrelated to the administration's recent military strikes on suspected chemical weapons facilities in Syria, action Russian Federation condemned. For owners, they're asked to ensure network devices are up-to-date, change default passwords, and ensure the firmware on the device is from a trusted source.
"Russia is our most capable hostile adversary in cyberspace."The Pentagon reported a 2,000 per cent surge in activity by Russian "troll" accounts.
Government-backed Russian hackers are using compromised routers and other network infrastructure to conduct espionage and potentially lay the groundwork for future offensive cyber operations, United Kingdom and USA authorities have warned. Most traffic within a company or between organizations traverses them. And they're usually not secured at the same level as a network server.
Russian government-sponsored hackers are compromising the key hardware of government and business computer networks in like routers and firewalls, giving them virtual control of data flows, the USA and Britain warned Monday.
"Many of the techniques used by Russian Federation exploit basic weaknesses in network systems".
"The activity highlighted today is part of a repeated pattern of disruptive and harmful malicious cyber action carried out by the Russian government", Federal Bureau of Investigation deputy assistant director Howard Marshall said in a statement online.