The technique a virus uses to achieve its execution. Malicious code typically tries to achieve two things: first, to propagate by infecting other systems, programs, or data; and second, to perform some malicious activity such as deleting or altering data, or to gather some intelligence on the attacked system. Some of the more common Means of Infection are the following:

        •   Opening an infected e-mail attachment

        •   Exploiting a security vulnerability of the operating system or an application

        •   Executing programs from untrusted sources, such as those on the Internet

        •   Sharing infected floppy disks, memory sticks, or other forms of mobile media

        •   Receiving infected attachments (either programs or data) through IRC, Instant Messaging, or file-sharing applications

        •   Visiting Websites containing malicious code

        •   Accessing systems locally with the intent to install a virus

See Also: Means of Transmission; Virus; Worm.