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.
Web threat
In August 2008, popular social networking sites were hit by a worm using social engineering techniques to get users to install a piece of malware. The worm installs comments on the sites with links to a fake site. If users follow the link, they are told they need to update their Flash Player. The installer then installs malware rather than the Flash Player. The malware then downloads a rogue anti-spyware application, AntiSpy Spider.