A. Android Threats: As we discussed in the previous section, Android is the most susceptible OS for threats and attacks. The authors in [30] stated three foremost explanations aspects for that: the shortage in reviewing for applications in Android official market; the openness; and the compatibility with other smartphones Apps. A set of different types of attack classes is presented in [7]. One class is a mal ware takes advantage of granting unaware applications permissions (permission-based) and performs its dirty roles. Soundcomber [11] is an example of mal ware takes advantages of given permission to access microphone to steal sensitive audio information and send it to a remote hacker. In [12] PlaceRaider is described; it is another example which uses the camera and accelerator permissions to perform a dirty stealing of sensitive data using a collection of unrealizable images. Second class
hunts the points of weakness in the Linux kernel and system libraries. In [13] it is classified Asroot as a Linux kernel mal ware and DroidDeluxe as malware exploits an OS daemon thread. Those two mal wares access the root privileges to activate their banditry. Third class mal wares target the graining of the hardware of the smartphones such as CPU, and memory. Other class uses the way of the settlement in a mobile device to do attacks to other device. The SMS, MMS, and Mail attacks are effective ways for the last class. Other taxonomy for the mal wares is categorized in [13]. Figure 4 briefs this taxonomy. It shows the different attack groups. First category is contains those mal wares which are installed into the device. Large set of those mal wares in this category using three social engineering methods. Repacking, which is popular one. It is the method of downloading normally the Apps and modifying dirtily those Apps and re-uploading them again to Android markets and seems like safe Apps. Updating attack which uses some technique of repacking but it is smarter by including only an update code to download the malicious content. Drive-by download attack, which is basically based on download dirty content without the users' knowledge using advertisements clicking or visiting untrusted websites. There is also other unclassified techniques such as those original Apps contain malicious procedures and those root-exploit based types. The second main category is activation based. It is the set of threats that use the system events by registration to perform their attacks. Those events are, for instance, the booting procedure or the SMS receiving process.