“My account has been stolen. Clash of Clans» is a constant complaint among the players of this Supercell title, who have made a mistake when exposing their data or have been victims of a cyber attack...
Beware: Reasons why your account can be stolen Clash of Clans
Generally account thefts occur due to overconfidence. Yes, it is the number one reason behind a theft report.
Many players know others only through social networks and provide them with the data. The most common form of data theft is the following shown in this video:
Another reason is to access fraudulent websites that offer free infinite gems in exchange for your IDs and passwords, thereby taking over your account.
The best thing you can do to protect your account Clash of Clans is to get a supercell ID and link it to the Google Play Store with all the protection mechanisms they offer.