Despite warnings from some of the biggest names in the financial world that it may be a bubble, bitcoin enthusiasts show no signs of slowing down yet. As of this writing, the price of one coin is nearly $19,000 – more than 20 times what it was at this time last year.

All of this has taken place while many investors don't fully understand how digital currencies work or retain value, and in spite of the fact that cryptocurrency adoption at most real-world stores has yet to take place. Now, Engadget describes how the fervor behind digital currencies may be linked with new developments in the online ad industry.

Websites Hijack User Power

Back in September, news broke that certain websites, including those of the television network Showtime, had been secretly harnessing the computer processing power of website visitors to mine cryptocurrency. (See more: Showtime Websites Used Visitors' Computer Power for Crypto Mining.)

Now, the trend has reemerged in the news, as a Twitter user spotted a Starbucks which was doing something similar, in this case in order to mine for Monero without the knowledge of its customers. Starbucks' reward site for Argentina was secretly running Coinhive's code to farm for Monero coins, using the computers of customers logged on to the coffee chain's wifi without their knowledge. As of now, Starbucks has yet to respond to inquiries about the mining operation.

Why the Shift?

Why might companies do this? It could be that website owners are looking for alternative, increasingly lucrative, ways of generating income from their visitors. It used to be that ads were the way to do this. However, with increased sensitivity among consumers and new ad blockers emerging all the time, in some cases it may be more profitable to give up on traditional online ads in favor of cryptocurrency mining efforts instead. (See more: Hackers Target Computer Rigs to Illegally Mine Cryptocurrencies.)

Websites favoring this underhanded approach look to services like Coinhive, which uses a JavaScript library to mine for digital currencies using the computing resources of users visiting a website. Coinhive itself is marketed to website owners as a way to "run your site without ads."

Consumers have long considered online advertising to be "unwanted, unsafe and prone to infectious malvertising," according to Engadget. The illicit farming of digital tokens has prompted a similar response, albeit one that is less widely disseminated at this point.

What's next for this secretive digital currency mining endeavor? Some consumers and security companies are already fighting back, producing products to detect and eliminate or block these protocols. However, as digital currencies continue to grow in prominence and value, it's a safe bet that this type of malicious CPU-harnessing will proliferate as well.

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