Mobile Application Security

Question 1

How does Android sandbox applications?

Answer 1

Using SELinux, the Linux user abstraction (one app publisher -> unique UID), the permission concept (maps to Linux group ids)

Question 2

What is different for “dangerous” permissions?

Answer 2

They have to be requested explicitly at runtime since Android 6 Marshmellow

Question 3

What does an Android APK contain?

Answer 3

AndroidManifest.xml, classes.dex, res, lib

Question 4

What are the four main components of Android apps?

Answer 4

Activities, Services, Broadcast Receivers, Content Providers

Question 5

Name 4 Android IPC Mechanisms

Answer 5

Intents, Binder, Messenger, Content Providers

Question 6

What is the difference between explicit and implicit Intents?

Answer 6

Explicit intents target specific app components, implicit intents are caught via intent-filters, which are declared in AndroidManifest.xml

Question 7

Name 7 common vulnerabilities of Android apps

Answer 7

Leaking sensitive information via logging, Leaking components, Insecure communication, Weak input validation / sanitization, Tapjacking, Hardcoding sensitive information, Reverse Engineering & Code Tampering