Guess Who’s Texting You? Evaluating the Security of Smartphone Messaging Applications (NDSS Symposium 2012)

1. Guess Who’s Texting You?Evaluating the Security of Smartphone Messaging Applications (NDSS Symposium 2012) Sebastian Schrittwieser, Peter Frühwirt, Peter Kieseberg, Manuel Leithner, Martin Mulazzani, Markus Huber, and Edgar Weippl SBA Research gGmbH Vienna, Austria

2. Introduction • Related Work • Mobile Messaging Applications • Evaluation • Results • Conclusion Outline

3. In recent months a new generation of mobile messaging and VoIP applications for smartphones was introduced. • These services with a novel user authentication concept offer free calls and text messages. • The main contribution of our paper is an evaluation of the security of mobile messaging. Introduction

4. Introduction

5. User authentication is a popular field of research in information security, especially applied to distributed systems or for web services. • Smartphone application security without mobile messaging services has been evaluated in the past. • Recently, cloud storage services have attracted the interest of security researchers analyzing the implications of faulty authentication in that area. Related Work

6. All applications analyzed in this paper have one thing in common: They use the user’s phone number as the basis for identification. • iOS don’t allow applications to access the phone number, but Android can. • Benefit of typing number is that a WiFi-only tablet can be activated using the phone number of another device. • Attacker could enter other’s phone number and hijack account. Mobile Messaging Application

7. Messaging Application

8. Authentication Mechanism and Account Hijacking • Sender ID Spoofing/Message Manipulation • Unrequested SMS/phone calls • Enumeration • Modifying Status Messages Evaluation

9. Victim’s phone Code Code (SMS) Code Victim Attacker Server Authentication Mechanism and Account Hijacking

10. Modify Sender ID Message Victim Attacker Server Sender ID Spoofing/Message Manipulation

11. Victim1 Victim1’s phone Code (SMS) Code (SMS) Victim2’s phone Attacker Server Victim2 Unrequested SMS/phone calls

12. Attacker’s Address Book Attacker Server Other user’s information Enumeration

13. We analyzed the protocol for setting the status message and explore possible vulnerabilities that could result in unauthorized modification of status messages. • In practice, this approach would likely be combined with some sort of enumeration attack. Modifying Status Messages

14. Experimental Setup

15. Result

16. Account Hijacking

17. WhatsApp

18. WowTalk

19. EasyTalk

20. No verification. HeyTell

21. The authentication mechanisms of Forfone and eBuddy XMS are similar to Viber’s. Viber, Forfone, eBuddy XMS

22. If the number is not registered for the service yet, no verification is done. • Only if the number is already known to the system, a verification process via SMS is performed. Tango, Voypi

23. Other applications use the Extensible Messaging and Presence Protocol (XMPP). Sender ID Spoofing

24. All examined applications had some kind of timeout that thwarted real mass spamming. Unrequested SMS

25. Unrequested SMS (Cont.)

26. we selected the US area code 619, which covers the southern half of the city of San Diego, CA and enumerated the entire number range from 000-0000 to 999-9999. • 21095 valid phone numbers use WhatsApp. (2.5 hours) Enumeration

27. WhatsApp • WowTalk • Voypi Other Vulnerabilities

28. Future work might include security assessments of upcoming solutions slated for mass adoption such as Apple’s iMessage. • Furthermore, research towards an authentication scheme suitable as a best practice template for newly developed applications would be a welcome addition. Conclusion