This past weekend, Showtime websites were found to be running a script that allows the sites to mine visitors’ extra CPU power for cryptocurrency, as pointed out by users on Twitter. The afflicted sites included showtime.com and showtimeanytime.com, but the script has since been removed following reports from Gizmodo and other sites.

The crypto mining Javascript is called Coinhive, and according to the site, it was made as an alternative to banner ads as a way for website owners to get around pesky ad-blockers. Ironically, some ad-blockers have now included Coinhive on the list of the banned.

The script mines the cryptocurrency known as Monero. Launched in April 2014, Monero is meant to be a more anonymous version of Bitcoin because you can’t view transactions on a public ledger. Thirty percent of the proceeds go to Coinhive, while sites using the service, like Showtime and The Pirate Bay, keep the rest. For its part, The Pirate Bay has apologized for secretly running the script and then asked its users if they preferred ads or CPU mining. Surprisingly, many of the comments indicate a positive reception towards the idea.

Coinhive updated its site to include the statement: “We're a bit saddened to see that some of our customers integrate Coinhive into their pages without disclosing to their users what's going on, let alone asking for their permission.” Going forward, the service claims that it will now ask people browsing a site for permission before mining their CPU. Showtime declined to comment.

Screenshot attached of https://t.co/GUhBnYmwoe source code before, during, and after. pic.twitter.com/aIRQOCdixG — Bad Packets Report (@bad_packets) September 25, 2017

Update September 26th, 2:10PM ET: This article was corrected to reflect that Monero was launched in April 2014, not last month.