Earlier this month, Israeli adtech firm Spotad warned websites and publishers about cryptocurrency miners slipping into ads. The crypto-focused website, CoinDesk, reported on Spotad’s findings after speaking to the agency’s co-founder Yoav Oz, who said, “The mining protocol for the big cryptocurrencies, like bitcoin and bitcoin cash… to mine that kind of crypto requires high end servers and even GPU-based processing. Monero has a script that can perform well on CPUs that actually reside in any desktop, laptop, and mobile device.”

Mr. Oz didn’t disclose which network or which website has been affected by this, but stressed that malware targets the cryptocurrency Monero, simply because it is easier to mine. He then went on to warn online publications, claiming they should stay vigilant and focus on fraud detection.

While most internet users have probably encountered crypto miners, especially on torrent and video streaming websites, ad blockers and anti-virus software have been able to combat them efficiently. In September 2017, Motherboard‘s Jordan Pearson published an article about an efficient crypto ad blocker, after Piratebay had gotten its users to mine Monero without their knowledge.

Crypto mining YouTube ads

This, however, seems to have been just the beginning. YouTube was recently caught displaying ads with CPU-draining cryptocurrency miners, Ars Technica reported. Word of these problematic YouTube ads reportedly started on Tuesday, as people started complaining on social media websites. Their antivirus software detected the crypto miner Coinhive, they claim.

“YouTube was likely targeted because users are typically on the site for an extended period of time. This is a prime target for cryptojacking malware, because the longer the users are mining for cryptocurrency the more money is made,” security researcher Troy Mursch told Ars Technica.

In the crypto mining world, things seem to be developing incredibly fast. In October 2017, Extreme Tech warned about in-browser cryptocurrency mining, claiming that it is exploding all over the web. Abrasive and annoying pop-up ads have been replaced by crypto miners. WordPress plugins for mining cryptocurrency on user systems already exist and website owners have been using them to mine for cryptocurrencies, Monero in particular.

Not everyone considers this to be a danger. CEO of OTAMate (Android and iPhone mobile app developer), Carl Whalley published a blog post on LinkedIn, arguing that there are indeed some pros to in-browser crypto mining. “It looks like a website can set things up so each visitor ends up safely performing a little computational work to help the site owner mine some online currency,” Whalley wrote.

This would, in theory, allow website visitors to directly create money for website owners and perhaps, someday, completely eliminate ads, but it’s hard to tell how many website visitors would be comfortable with a solution like this, considering today’s ad blockers are quite efficient.

YouTube still hasn’t responded to the controversy and it remains unclear how many CPUs have been affected by cryptominers in YouTube ads.