Between thousands of photos, shared videos and information-intensive applications, your mobile phone’s internal storage can fill up quickly. And if you aren’t sure what is using up the most space, it often involves sifting through the settings to find the culprits.

However, there are a few apps that can do that for you. They scan all the folders, browser cache, system files and games to determine where you can free up some real estate. Many of these apps are helpful, but some only pretend to clean up your device.

Read on for 13 dangerous apps recently found to be hiding malware.

McAfee’s Mobile Research Team found several apps on the Google Play Store that aren’t what they seem. The apps promote themselves as mobile cleaners, promising to remove junk and unused files so your Android device can run smoother.

But instead of doing that, the apps hide malware and continuously show advertisements on the infected device. Furthermore, you don’t need to open the app for the malicious code to start working, as simply downloading it to your phone is enough to trigger it.

Learn the tech tips and tricks only the pros know.

According to McAfee, some of the apps hide on the infected device by changing their icon and name to something familiar. The built-in automatic advertising is so aggressive that it pops up every time you install, uninstall, or update apps.

Here’s a list of the malicious apps grouped into the number of downloads:

In most cases, Google quickly acts when malicious applications appear on the Play Store, removing them before spreading too wide. But don’t leave cybersecurity up to Big Tech. You also need to take precautions on your own.

Here are some tips on how to stay safe:

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