Cryptojacking is the surreptitious and unauthorized use of a computer for the resource and power-demanding requirements of cryptocurrency mining. The attack essentially creates a cryptomining bot, and the attacker may coopt many systems to create a botnet.
In another twist on the practice, researchers for Chinese cybersecurity vendor Qihoo 360's Netlab team recently reported that an Ad network was running cryptomining software in the browsers of unsuspecting users who visit the advertisers' websites. Because programmatic advertising places ads automatically, site owners have little control over the issue. The malware used domain generation algorithms (DGAs) to bypass ad blockers and serve ads to all site visitors.
Cryptojacking techniques have been proposed for beneficial uses as well, such as providing a revenue stream for sites and services or crowdfunding for disaster relief efforts. Nevertheless, from the perspective of end users and network administrators, cryptojacking is primarily a drain on processing and power resources.