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Android Security Architecture: A Deep Dive into the Linux Kernel & SELinux By Security Research Team | Advanced Level TL;DR: Android's security model rests on four pillars: Linux kernel isolation, SELinux mandatory access control, application sandboxing, and the permission system. This post breaks down each layer with real exploitation scenarios. 1. The Linux Kernel Layer Every Android app runs as a separate Linux user. When you install an app, the system assigns it a unique User ID (UID). This means app A cannot read app B's files because they run under different UIDs — standard Linux file permissions in action. $ ps -A | grep app_ u0_a123 1234 567 com.whatsapp u0_a456 7890 111 com.facebook.katana The kernel also enforces capabilities . Apps run with CAP_NET_ADMIN stripped, preventing raw socket creation on non-rooted devices. This blocks packet injection from user-space apps. Exploit Scenario: CVE-2016-5195 (Dirty COW) allowed a local app to ga...

Android Security Architecture: A Deep Dive into the Linux Kernel & SELinux By Security Research Team | Advanced Level TL;DR: Android's security model rests on four pillars: Linux kernel isolation, SELinux mandatory access control, application sandboxing, and the permission system. This post breaks down each layer with real exploitation scenarios. 1. The Linux Kernel Layer Every Android app runs as a separate Linux user. When you install an app, the system assigns it a unique User ID (UID). This means app A cannot read app B's files because they run under different UIDs — standard Linux file permissions in action. $ ps -A | grep app_ u0_a123 1234 567 com.whatsapp u0_a456 7890 111 com.facebook.katana The kernel also enforces capabilities . Apps run with CAP_NET_ADMIN stripped, preventing raw socket creation on non-rooted devices. This blocks packet injection from user-space apps. Exploit Scenario: CVE-2016-5195 (Dirty COW) allowed a local app to gai...