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.
Vandalism
Cybervandalism is vandalism on the internet. For example, vandalism on Wikipedia involves adding questionable content, removing content, or changing content in order to make it questionable, generally with the objective of harming Wikipedia's reputation. Forms of online vandalism have been recorded, the most common of which is website defacement. Vandalism on web maps has been called "cartographic vandalism". Another form of cybervandalism is creation of malware, such as viruses, Trojan horses, and spyware, which can destroy computers, and in some cases even steal money from the computer owners, wherein the malware creator blackmails the owner to pay them money or give out their credit card number or else they won't get the use of their computer back. Some even go as far as making a time limit where if the owner doesn't pay or give personal information within a certain time, the malware permanently destroys the computer.