The number of websites hosting code that mines for crypto-coins using visitors’ CPU power went up a staggering 725% in a four-month period, Cyren reports. The massive increase took place between September 2017 and January 2018 and was observed upon the monitoring of a sample of 500,000 sites, the security company says. The firm also noticed that some websites would run the crypto-mining scripts on more pages, knowingly or not. The number of new mining sites registered a massive increase in October, plateaued in November, and then doubled in December and again in January, which suggests that the rate at which crypto-mining is spreading is accelerating. This jump in activity, however, isn’t surprising, considering the meteoric rise in crypto-currency values over the past months, Cyren points out . Most of the scripts were designed to mine for Monero, a virtual coin that increased by almost 250% in value recently, attracting a lot of attention. The spike in mining sites was also fu...