Some viruses just copy themselves from one computer to other. Other viruses may steal data or files, permit eavesdropping or unauthorized access, destroy data and cause other consequences. It is also possible for a virus to carry multiple payloads.

Present-day malware is less likely to incorporate a payload that causes damage to system files; instead, they enable backdoor access to a user's computer and the theft of sensitive information.

Some of the ways to execute a payload include:

• By using an unprotected computer (computer without an anti-virus installed) connected to a network
• By booting the computer using an infected removable medium
• By opening an infected file
• By executing an infected program
• By activating a logic bomb