Malware
Malware authors target bugs, or loopholes, to exploit. A common method is exploitation of a buffer overrun vulnerability, where software designed to store data in a specified region of memory does not prevent more data than the buffer can accommodate being supplied. Malware may provide data that overflows the buffer, with malicious executable code or data after the end; when this payload is accessed it does what the attacker, not the legitimate software, determines.
Wiper (malware)
A wiper is a class of malware whose intention is to wipe the hard drive of the computer it infects.
A piece of malware referred to as "Wiper" was allegedly used in attacks against Iranian oil companies. In 2012, the International Telecommunication Union supplied Kaspersky Lab with hard drives allegedly damaged by Wiper for analysis. While a sample of the alleged malware could not be found, Kaspersky discovered traces of a separate piece of malware known as Flame.