This is just for educational purposes only.
Full report from Dr Web:
Doctor Web’s malware analysts have discovered malicious apps on Google Play that steal Facebook users’ logins and passwords. These stealer trojans were spread as harmless software and were installed more than 5,856,010 times.
The article below explains everything in layman terms, including what Google had done to prevent this in the future:
A total of nine Android apps with a combined install base of 5.8 million have been caught stealing Facebook passwords.
Ways to avoid malware on Android
Users can avoid malware on their Android devices if they follow four, easy tips.
List of past security issues and malware on Google Play - Wikipedia
Images of the malicious Android apps. Screenshots from the Dr. Web report (link above). Credit to the owner.