Yo, We Shouldn't Trust Strange Apps That Become Wildly Popular Out of the Blue

Yo is a simple, strangely addictive app: You download it and add some friends, and then it lets you say “Yo” to them.

Yep, that’s it.

Yo became wildly popular seemingly out of the blue this week. After news reports of Yo receiving $1 million in venture capital funding were widely mocked as a sign we’re all living in another tech bubble, curious people starting downloading it to see what it was all about.

By Thursday, Yo was everywhere — including the Top Free App list in Apple’s App Store and this writer’s iPhone. On Friday, Yo was hacked.

Some nefarious types have been able to crack into Yo — which makes users verify their phone numbers and activate push notifications before the app can set about on its singular purpose — to send unwanted push notifications and grab users’ digits.

One of the app’s creators, Or Arbel, told TechCrunch that Yo is having “security issues” and “we are taking this very seriously.”

But Yo was a golden opportunity for troublemakers and hackers: An app that everybody’s downloading, which requires users to enter in their phone numbers and turn on push notifications, and one that certainly doesn’t have anything resembling an effective internal security team. If you’re somebody who goes around looking for ways to make trouble on people’s phones, Yo was a prime target. It’s really no wonder it was hit.

The lesson here, Yo? The next time an app falls from the heavens and lands on everybody’s phones, maybe we should think twice before installing it. Just because all your friends are doing it, doesn’t mean you should, too.

Contact us at letters@time.com.