You decided it was worth maintaining an extremely paranoid policy when configuring your firewall rules. Therefore, you had your management approve the implementation of a security policy stance to deny all inbound connection requests to your corporate network. How is it possible that you still suffer from remote exploits that your adversaries are using to obtain interactive sessions inside your firewall?

A.
TCP splicing is easy to do.

B.
Internal software may be vulnerable.

C.
UDP vulnerabilities are well-known and exploited.

D.
ICMP hijacking attacks can still succeed through any firewall.