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.
Linux Spike Trojan malware
Linux Spike Trojan malware, more widely known as MrBlack, is a type of malware that infects routers, and eventually spreads to other routers. Incapsula, an internet security firm, first saw this malware in December 2014. This tool is prone to attack devices that still use the default credentials. A "bot" is a type of malware that allows an attacker to take control over an affected computer. Also known as "Web robots," bots are usually part of a network of infected machines, known as a "botnet," which is typically made up of victim machines that stretch across the globe.