A persistent threat or attack is one that maintains continuous access to its target once it has been exploited. This means that initial exploitation is only performed once . Persistent attacks are often aided by malware and this type of attack is able to stay undetected for long periods of time, otherwise this attack would not be possible.

Here are some types of malware/concepts related to persistence:

Advanced Persistent Threat (APT):

An APT is a type of persistent threat actor . Their ability to stay undetected is what makes them "advanced" . A lot of APTs are highly experienced and may work for states.

Backdoor:

A backdoor is the concept of continuous access to high privilege accounts , usually the root account . The exact software used to carry out these attacks is known as a rootkit . Rootkits are meant to enable long-term access to systems. In a sense, they allow persistent attackers to blend into the system.

Remote Access Trojan (RAT):

In course 3, we very briefly talked about Trojan attacks. A Trojan horse , or Trojan, is a type of malware that is disguised as unharmful software . Similarly, a remote access Trojan is a malware that aids in persistence attacks. Like its name implies, RATs function like backdoor attacks , granting root privileges remotely, also for extended periods of time.