Backdoors are called a variety of malicious programs, as well as hidden access to the computer, specially created by the developers to perform unauthorized actions. Backdoors perform two main functions: online access to data, remote control of the computer. The product features are huge. Backdoor gives access to an attacker to the victim’s computer, so it can do everything on it, as the owner, but only remotely.
There are several methods that Sucuri uses to determine whether a backdoor has been installed on the website (White list, Blacklist, Check for anomalies).