What’s in Your Dongle and Bank Account? Mandatory and Discretionary Protection of Android External Resources Literature by S. Demetriou et al. Presented by Emma Hu Literature by S. Demetriou et al. Presented by Emma Hu

Motivation  Increase use in smartphone accessories such as Bluetooth earpieces, health devices, fitness bands etc.  Increase in malicious attacks  Previous studies show that external devices connected to Android are vulnerable  Increase use in smartphone accessories such as Bluetooth earpieces, health devices, fitness bands etc.  Increase in malicious attacks  Previous studies show that external devices connected to Android are vulnerable

Background  Android security model  Discretionary access control (DAC) system  SEAndroid (Security Enhanced Android)  Mandatory access control (MAC) system built on top of android  Security context  user: role: domain or type [:level] and a SID  Android security model  Discretionary access control (DAC) system  SEAndroid (Security Enhanced Android)  Mandatory access control (MAC) system built on top of android  Security context  user: role: domain or type [:level] and a SID

Problem  SEAndroid does not have the granularity for controlling external resources  Bluetooth, NFC, SMS ID, Audio port  SEAndroid does not have the granularity for controlling external resources  Bluetooth, NFC, SMS ID, Audio port

Results  SMS  SMSDispatcher broadcasts to all apps that register with the event have the RECEIVE_SMS permission  SMS and MMS fully exposed to those with READ_SMS or RECEIVE_SMS permissions  Audio  Completely unprotected when connected to the phone’s Audio jack  NFC  5/17 popular NDC apps include storage of sensitive information  No authentication and encryption protection  SMS  SMSDispatcher broadcasts to all apps that register with the event have the RECEIVE_SMS permission  SMS and MMS fully exposed to those with READ_SMS or RECEIVE_SMS permissions  Audio  Completely unprotected when connected to the phone’s Audio jack  NFC  5/17 popular NDC apps include storage of sensitive information  No authentication and encryption protection

Table 1: top apps from Google play Figure 1: example of a Bluetooth app

SEACAT  Employs a hybrid MAC & DAC approach  Extends SEAndroid’s MAC to protect resources with distinct identifier e.g. SMS, NFC  Adds in a DAC module to allow user and app developer to specify interaction rules  Focuses on protecting Bluetooth, Audio, NFC, Internet, and SMS channels  Employs a hybrid MAC & DAC approach  Extends SEAndroid’s MAC to protect resources with distinct identifier e.g. SMS, NFC  Adds in a DAC module to allow user and app developer to specify interaction rules  Focuses on protecting Bluetooth, Audio, NFC, Internet, and SMS channels

Details  Challenges  SEAndroid does not model external resources  Integration with current Android DAC and SEAndroid Mac  Design Implementation  Policy specification – new categories of types e.g. BT_type, NFC_type  App labelling – grant trusted apps permissions  External resource labelling  Challenges  SEAndroid does not model external resources  Integration with current Android DAC and SEAndroid Mac  Design Implementation  Policy specification – new categories of types e.g. BT_type, NFC_type  App labelling – grant trusted apps permissions  External resource labelling

Fig 2. Screenshot of SEACAT App labelling and Device labelling

Fig 3. SEACAT Architecture

Fig 4. SEACAT Security hook

SEACAT Results  Effectiveness  Successfully prevents unauthorised resource access  Performance  Overhead is mostly negligible  Largest overhead is 279.9ms (total time ) for Bluetooth pairing  Effectiveness  Successfully prevents unauthorised resource access  Performance  Overhead is mostly negligible  Largest overhead is 279.9ms (total time ) for Bluetooth pairing

Paper Summary  Android is not designed to handle external resources  SEACAT is introduced as a new security system to extend Android’s security model  MAC and DAC across different Android layers  Android is not designed to handle external resources  SEACAT is introduced as a new security system to extend Android’s security model  MAC and DAC across different Android layers

Issues and Improvements  The paper only looks at Bluetooth, NFC, Audio, SMS, and Internet  Doesn’t account for other channels like Wireless and Infrared  Doesn’t offer MAC protection for audio devices as it can’t distinguish between types of audio devices.  Only analysed one “Audio” device (Jawbone UP)  User / developer has to manually construct security rules / policies which decreases usability  Doesn’t protect against spoofing attacks  SEACAT assumes kernel is not compromised  The paper only looks at Bluetooth, NFC, Audio, SMS, and Internet  Doesn’t account for other channels like Wireless and Infrared  Doesn’t offer MAC protection for audio devices as it can’t distinguish between types of audio devices.  Only analysed one “Audio” device (Jawbone UP)  User / developer has to manually construct security rules / policies which decreases usability  Doesn’t protect against spoofing attacks  SEACAT assumes kernel is not compromised

References  [1] Demetriou, S., Zhou, X. Y., Naveed, M., Lee, Y., Yuan, K., Wang, X., & Gunter, C. A. (2015). What's in Your Dongle and Bank Account? Mandatory and Discretionary Protection of Android External Resources. In NDSS.  [2] Demetriou, S. (2014). Android at risk: current threats stemming from unprotected local and external resources.  [1] Demetriou, S., Zhou, X. Y., Naveed, M., Lee, Y., Yuan, K., Wang, X., & Gunter, C. A. (2015). What's in Your Dongle and Bank Account? Mandatory and Discretionary Protection of Android External Resources. In NDSS.  [2] Demetriou, S. (2014). Android at risk: current threats stemming from unprotected local and external resources.