The NSA, FBI and CISA have warned of 16 vulnerabilities in network software from 10 brands, including Cisco, Fortinet, Netgear, MikroTik, Pulse Secure and Citrix. Most of the vulnerabilities are classified as critical and were made public between 2018 and 2021.

The warning includes exploitation of bugs affecting small business routers, network attached storage (NAS) devices, and enterprise VPNs. It also includes compromised specialized authentication servers used by large telecommunications companies and network service providers.

According to the security agencies, the hackers who exploit the bug work for China, and the campaign is part of a broader effort to steal and manipulate network traffic.

To protect against such vulnerabilities, authorities recommend patching affected devices, removing or isolating compromised devices from the network, and replacing end-of-life hardware.

Other security measures include disabling unused or unnecessary services, ports, protocols and devices and enforcing multi-factor authentication “for all users, without exception.”