It's hard to escape ads these days. Not only are they appearing inside full-price games and within Windows, but thanks to some sneaky app developers, they're also invading our smartphones. Thankfully, Google is finally cracking down on one of the worst elements of app-based advertising: malware-like lock screen ads.

Through an update to the Google Play Policy Center, Google revealed it is banning apps from its store that introduce ads to a handset's lock screen. The practice has been found in applications such as Hotspot Shield VPN and ES File Explorer.

The only exception to the new rule is if the app's sole function is that of a lock screen.

"Unless the exclusive purpose of the app is that of a lockscreen, apps may not introduce ads or features that monetize the locked display of a device," explains Google, so we should stop seeing them in Google Play apps like VPNs and malware scanners.

Google hasn't said when it will start pulling the offending apps from its store but expect to see a formal announcement soon.

While some see these lock screen ads as nothing more than an annoyance, it's been shown that some could be used to circumvent a handset's security systems. In 2016, a Reddit user found that if someone woke a device with a SuperCharge lock screen enabled, they could long-press on an ad to open it in a browser. The method could give an attacker access to a handset's data by skipping the PIN and fingerprint requirements.