Security firm Zscaler has discovered a malicious app for Android devices that is able to hold the devices and their users at ransom.

The app is named Adult Player, and it lures users to download and install the app by promising free pornography. The app then secretly takes pictures of the user with the device's front-facing camera.

Afterwards, the malicious app then locks the device, displaying a ransom note of $500 that the user must pay before getting back access into the device. The app also displays the picture that it took of the user as an added way to scare the user into shelling out the ransom.

This kind of app, widely known as ransomware, has been growing as a tool for cybercrime, according to a security expert. Ransomware typically demand money from users as they threaten to release private data or wipe out the contents of a device.

Adult Player is the second pornography-masked ransomware that was discovered by Zscaler. The app could not be seen in stores such as Google Play, with users having to install the app directly through a link on a webpage.

According to Zscaler, the ransom message of the app kept the screen of the locked device turned on continuously, with the ransom message reappearing even if the user restarts the device.

To circumvent the ransomware, Zscaler said that users should boot their device into safe mode, the process of which varies between manufacturers. Safe mode loads the device's operating system without any third-party apps, so the user can access the device and then delete the malicious app.

Intel Security said that ransomware saw an increase of 127 percent since last year, with the malicious apps mostly affecting laptops and desktop computers.

"One of the reasons for the increase is that it's very easy to make," said Intel Security chief technology officer Raj Samani.

According to Samani, cybercriminals can pay others to do all the work, with the payoff being exceptionally high. One group that was tracked by Intel Security made over $75,000 in a span of 10 weeks, Samani said.

"Apps like this rely on the embarrassment factor. If you don't pay, your reputation is on the line," Samani added.

To stay safe from such apps, Samani said that users should use basic common sense. Users should only download apps that are listed on the Google Play Store and should not download apps directly from links.