Investing.com - Criminals have stolen $1.2 billion in cryptocurrencies in 2017, according to a non-profit group.The Anti-Phishing Working Group estimates that only 20% of the funds have been recovered by authorities. It did not say how the funds were stolen.Cryptocurrency theft, especially by cyber criminals, has exploded in recent years along with the growing number of digital coins and trading platforms. Hacker attacks on two major exchanges this year --one in Italy and another in Japan--netted about $650 million.Japan recently formed a special law enforcement task force to combat cryptocurrency theft by cyber criminals.An Ernst & Young study found that more than 10% of the money raised though initial coin offerings, ICOs, in the past two years had been stolen by hackers, usually through the practice of phishing.