A malicious program that signals to cybercriminals that an infected device is connected to a network. The message contains information about the computer or smartphone and its owner, for example, IP address, open port number, and email. Signals can be sent via email, a special call to the cybercriminals’ website, or instant messaging.

Such programs are used in multi-component Trojans to notify attackers about the successful installation of malicious programs in the target system.