Maintaining access
Once a foothold is established (that is, remote access), it can be removed very quickly, as systems can be rebooted and users can log out. This is where persistent access comes in; it can be achieved in a number of ways. The best strategy for the maintenance of persistent access is to use multiple techniques simultaneously.
For example, one can plant a physical back door (Dropbox) into the network that can later be accessed within their wireless range. A more creative way is to set up a scheduled task on the compromised machine to run at boot and to execute periodically, for example once a day: