A hacker added code to several web sites of CBS’s Showtime network that stole computing power from online visitors in order to mine digital currencies, offering a new twist on illicit profiteering from the boom in cryptocurrencies.
The exploit was discovered over the weekend and the unauthorized code was removed by Monday, tech news site The Register reported. Showtime’s popular shows include Homeland, Billions, and Shameless.
New coins in digital currencies like bitcoin and ethereum are created through the number crunching of mathematical calculations that verify transactions. That typically requires banks of high-powered computers gobbling huge amounts of electricity–and cutting into the profits of “mining” the new coins. The unknown hacker or hackers used the CBS (CBS) unit’s web sites to get around that cost by, in effect, hijacking the processing power of visitors to the web site to run a mining program for a digital currency called Monero.
Using javascript code, the hackers were able to gain up to 60% of the processing capacity of visitors’ computers to mine Monero, one of the many smaller alternatives to leading currency bitcoin that have cropped up over the past few years. Each Monero digital coin is worth more than $94. The currency bills itself as “a secure, private, and untraceable cryptocurrency.”
The code was placed in sections of the web site that appeared to be part of analytics software from online data analysis firm New Relic.
Get Data Sheet, Fortune’s technology newsletter.
Showtime declined to comment to Fortune.
New Relic (NEWR) said it was not responsible for the hacking. “We take the security of our Browser Agent extremely seriously and have multiple controls in place to detect malicious or unauthorized modification of its script at various points along its development and deployment pipeline,” New Relic said in a statement. “Upon reviewing our products and code, the HTML comments shown in the screenshot that are referencing newrelic were not injected by New Relic’s agents. It appears they were added to the website by its developers.”
The Showtime hack wasn’t the first appearance of the javascript mining code. Last week, the Pirate Bay, the popular web search site for bit torrent files, added similar code to use visitors’ computers to mine Monero. The site fessed up to the maneuver in a blog post, saying the idea was to raise money to finance the site without needing to rely on advertising.
“As you may have noticed we are testing a Monero javascript miner,” the web site noted. “This is only a test. We really want to get rid of all the ads. But we also need enough money to keep the site running.”
(Updated on Sept. 26 with comment from New Relic.)
