Referring to this vuln:
http://bluebox.com/technical/android-fake-id-vulnerability/
and this permission:
http://developer.android.com/guide/topics/manifest/permission-element.html
"signature" A permission that the system grants only if the requesting application is signed with the same certificate as the application that declared the permission. If the certificates match, the system automatically grants the permission without notifying the user or asking for the user's explicit approval.
