A few of the common objectives of malware are: The virus replicates and encrypts itself, changing its code just enough to evade detection by antivirus programs. An old but still prominent type of malware, macro viruses, remain popular with hackers. Fake file names tempt the recipients to open the files, activating the viruses. Macro viruses usually arrive as Word or Excel documents attached to a spam email, or as a zipped attachment.

A file infector can overwrite a computer's operating system or even reformat its drive. The file infector can burrow into executable files and spread through a network.

These are the three most common examples: There are many different types of viruses.