According to security firm 360 Netlab, 241 of the top 100,000 websites as rated by Alexa contain code that uses visitor's computer power to mine cryptocurrency.

Porn sites represent almost half of those practicing computer power theft

Of the 241 offending sites, 49 percent were porn sites.

The sites had names such as streamxxx.tv the type of site likely to be visited by a novice porn viewer who was watching porn for the first time and had Googled "porn". A proxy site for the popular torrent site The Pirate Bay also contained the code.

As the value of cryptocoins increased so did mining by hackers. Some methods have been inventive as hackers hacked an Argentine internet provider.

Effects of mining hacks on compuiters

The thief uses code that infects your browser. It can use your computer resources and thus slow down performance. Last year, Symantec predicted that in-browser mining would turn into an arms race as the hackers come up with more inventive and invasive ways of mining cryptocoins using stolen computer power.

A new version of the browser Opera has a built-in defense against mine hacking as shown on the appended video.

360Netlab

360Netlab continuously analyzes DNS traffic. Based on these analyses they have developed a DNSMon detection system that is able to analyses various anomalies and correlations in the DNS traffic.

Very few sites actually have the mining codes embedded in them, just 0.24 percent of the top 100,000 websites according to Alexa. Of the top 300,000 there were 629 websites or just 0.21 percent offenders. Aside from porno sites ad sites contained 7 percent of offending sites, mining also 7 percent with film and television having 6 percent.

360Netlab blog describes the various mining site families, providers that are entering an increasing market. The site also discusses the main advantages as well as disadvantages of using the DNSMon system to detect correlations between content site domain and mining site domains.