Tuesday, U.S. security research firm FireEye warned that the infection could help cyber criminals to access huge amounts of data without being detected.
Affected hardware includes the Cisco 1841, 2811, and 3825 routers. Other models are likely vulnerable to the attack.
FireEye said the router’s position in the network makes it an ideal target for re-entry or further infection.
The attacks are expected to hit government agencies and multiple industries. Hackers prefer routers because they function outside the borders of the firewalls and other security tools.