現存作業系統的安全強化議題:以Android Open Source Project為例

Abstract

智慧型行動裝置具備連網、照相、錄音、定位等能力，並可透過應用程式幻化出多樣的功能與型態，如收發訊息、電子郵件、地圖導航等，帶給了使用者許多的方便，卻也造成許多的資安隱憂。為了更完整地掌控整個行動裝置，市面上存在著許多現成的MDM(Mobile Device Management) App，透過MDM我們可以限制應用程式或是整部裝置進行照相、錄音等敏感行為，以符合企業的資安政策，或是當手機遺失之時，遠端清除裝置內的敏感資訊。 然而一般層級的應用程式並無法達到較為完整的掌控，所以我們將MDM client 提升為系統層級的應用程式，如此一來便能使用更為強力的API來控制裝置，並分析AOSP(Android Open Source Project)的原始碼，在掌控功能的關鍵位置插入我們自訂的程式碼，更進一步強化MDM對於整部裝置的掌控力，以及利用SELinux on Android來達到更為強力且完整的掌控。

Mobile devices have many function such as surfing the Internet, taking pictures, recording and locating. And can be turned to many functions and features like receiving and sending message, e-mail, GPS, etc. Mobile devices bring users a lot of convenience, but also bring us privacy-sensitive problem. For the full control of the whole mobile, there are many off-the-shelf MDM (Mobile Device Manager) App. Through MDM, we can limit sensitive behaviors of Apps or the whole device for the privacy policy of the corporate. But normal Apps can’t take powerful control of the whole device. So we install MDM client on the device as system App, thus MDM can take advantage of system API. Then we trace the source code of AOSP (Android Open Source Project). And insert some hooks in the points which control the usage of sensitive behavior to make MDM more powerful. After that, we use SELinux on Android to achieve the goal of deeper control of the whole device.