Firewalls

Do you know your enemy?

The state of Information Security

Malware authors have figured out how to evade AV by continually tweaking their binaries. They can circumvent content filtering systems by hacking legitimate sites (banner ads, etc.) that users are allowed to access. They flow right by IDPS and Malware Detection Systems through the same type of techniques. Firewalls offer good protection for inbound connection attempts, though the threat vector now consists of an attacker riding back in on legitimate outbound connections.

 

National Cyber Alert System - Understanding Firewalls