Be it legitimately or covertly, it seems that cryptomining is becoming a popular method of making money. We've already seen miners used in websites such as the Pirate Bay and in malicious apps that can physically damage phones. Now, they've briefly appeared in the Mac App Store.

As reported by Ars Technica, the Mac scheduling app Calendar 2 was updated by developer Qbix with the option to unlock all its advanced features for 'free.' This would normally cost a one-off $18 fee or $0.99 per month, but users could turn on these premium functions by allowing the app to run the xmr-stak Monero miner in the background. They could also choose to disable all advanced features and pay nothing.

While including an option to mine crypto by default raised concerns, there was a bigger problem: bugs in the app meant that mining would run indefinitely, even when users changed the default setting. Additionally, the miner was only supposed to use 10 - 20 percent of a Mac's computing power, but it was consuming much more---up to 200 percent, in some cases.

"In short, as you can imagine, these two bugs caused issues for many of our users. We got a lot of messages saying "I love your app and used it for many years, but this version is kicking my computer into overdrive! Please fix it ASAP." (Paraphrased.) And so forth. What started out as a well-meaning option to just let people try out a new way to get all features unlocked became an option that made many people associate "mining" with huge CPU consumption." wrote Qbix founder Gregory Magarshak in a statement to Ars Technica.

Not long after the article went live, Qbix said it would remove the mining option. Magarshak said it wouldn't appear in future versions of the app, and that he hopes the decision will set a precedent for other apps.

We have decided to REMOVE the miner in the app. The next version will remove the option to get free features via mining. This is for three reasons:

1) The company which provided us the miner library did not disclose its source code, and it would take too long for them to fix the root cause of the CPU issue.

2) The rollout had a perfect storm of bugs which made it seem like our company *wanted* to mine crypto-currency without people's permission, and that goes against our whole ethos and vision for Qbix.

3) My own personal feeling that Proof of Work has a dangerous set of incentives which can lead to electricity waste on a global scale we've never seen before. We don't want to get sucked into this set of incentives, and hopefully our decision to ultimately remove the miner will set some sort of precedent for other apps as well.

Ultimately, even though we technically could have remedied the situation and continued on benefiting from the pretty large income such a miner generates, we took the above as a sign that we should get out of the "mining business" before we get sucked into the Proof of Work morass of incentives.

Apple has been silent on the matter but presumably okayed the update that added the mining option. However, Calendar 2 is no longer available from the Mac App Store. Whether Qbix is currently updating it to remove the function, or if Apple decided to pull the app, is unclear.

Last month, website gave visitors with adblockers the option of disabling them or allowing the site to utilize their CPUs to mine Monero.