During a four-day period at the beginning of 2014, web site Yahoo reported that malware had infected its ads for the purpose of mining bitcoins.
Bitcoin mining is the process of using computer processing to generate and create more bitcoins. When a computer is able to properly guess 25 figures, a new bitcoin is created.
Due to the high valuation of bitcoins at the start of 2014, cyber criminals have begun spreading malware in order to mine bitcoins. The malware installs a program on an infected computer to use its processing power. The user of the computer generally does not know that the computer is mining for bitcoins, but may notice that the computer is running a little slower.
The infected ads on Yahoo affected users in Europe. According to a cybersecurity firm, there were around 27,000 infections of bitcoin malware for every hour that the ads were being displayed on Yahoo. Up to two million computers could have been infected with the malware.
Source: Jane Wakefield, “Yahoo malware enslaves PCs to Bitcoin mining,” BBC News, January 8, 2014.