An attacker is often required to face a number of challenges in his activities.
Two of these challenges include –

Overcome network barriers (network policies, segmentation, etc.).
Perform different operations in “stealth mode” so he won’t get caught.

One good way to deal with these challenges is by using ICMP Tunnel when trying to create a stealth connection that can cross the different barriers in the network.

ICMP Tunneling can be done by changing the Payload Data so it will contain the data we want to send.

Usually, it contains a default Payload Data such as this ASCII string — “abcdefghijklmnopqrstuvwabcdefghi”

If we encapsulate an HTTP packet inside the Payload Data, we will get the most common way of this method- sneak out of a Pay-for-WiFi.

This can be achieved by using a proxy server that waits for ping messages and sends them as needed (for example — as HTTP).