In modern times mobile devices are a increasing technology and malicious users are increasing as well. On a mobile device it often exist valuable private information that a malicious user is interested in and it often has lower security features implemented compared to computers. It is therefore important to be aware of the security risks that exist when using a mobile device in order to stay protected.In this thesis information about what security risks and attacks that are possible to execute towards a mobile device running Android will be presented. Possible attack scenarios are attacking the device itself, the communication between the device and a server and finally the server.