Legitimate, non-malicious programs use overt channels to communicate within computer systems. Trojans often use covert channels to penetrate and attack target machines and networks. Which of the following options is not an example of covert channel use?

An attacker uses ICMP tunneling to mask their exploit

A man-in-the-middle attack is executed in network transmissions from an employee's client machine

An employee visits a phishing website, and is socially engineered to share their online banking credentials

An attacker deploys a reverse WWW shell to sneak into a target network via TCP/IP ports 80 or 443

Explanation

Using phishing websites are an example of an overt attack, that technique doesn't use covert channels. Covert channel attacks usually add, alter, and sniff data in packets that are generated by authorized users. If social engineering is necessary, that's an overt attack! EDIT2: agreed. I don't see the covert channel used in this attack.