Attacks coming from nearly 4,000 IP addresses take aim at VPNs, SSH and web apps. //

Talos said Tuesday that services targeted in the campaign include, but aren’t limited to:

Cisco Secure Firewall VPN
Checkpoint VPN
Fortinet VPN
SonicWall VPN
RD Web Services
Mikrotik
Draytek
Ubiquiti.

...

Additionally, remote access VPNs should use certificate-based authentication.