People increasingly use mobile devices to access the Internet. An InternetNZ-funded survey conducted by CROW in 2015 shows that 54.6% of New Zealand mobile users tend to own more than one mobile device and more than 46.4% of them usually use Internet-connected applications on their mobile devices such as social networking (40.7%), Internet browsing (29.9%), and emailing (26.9%). While cyber space and the digital world orbit faster than the Earth, new security threats targeting mobile devices emerge. A security policy has to be well planned to deal with the threats. In this article, I would like to introduce a mobile security solution based on context-aware computing for refining a security policy to adapt to the world-wide-wild cyber space.