Via third party Android App Stores.
Hackers and scammers are now distributing a version of Minecraft: Pocket Edition that are infested with trojans and hijack your phone into sending text messages to costly premium numbers.
To add insult to injury, unlike other knock offs or trojan scams that are distributed, these ones actually have the audacity to be sold (for €2.50 rather than the usual €5.40); so you are essentially paying money to be screwed over.
This trojan infested version is available only on third party app stores, and not Google Play. A side corollary of this is that it is also only available on Android, and not iOS (which, because of its locked down nature that only permits apps from the App Store to run, remains secure).
Minecraft developer Mojang did include checks within the Android version of its game to prevent tampering with its code, but it appears that this specific version seems to manage a workaround.