Storage of sensitive data in a Java enabled cell phone

MSc ThesisTommy Egeberg

June 2006

Agenda

• Introduction • Problem• Methods• Results• Conclusion• Further Work

Introduction

• Cell phones → small computers• Stores a lot of sensitive information

– RMS, email, SMS, calendar …

• Able to run Java applications– Mobile SSO solution

• Store passwords

-Introduction

Main problem

Will a Java MIDlet on a cellular phone be a secure location to store sensitive information?

-Problem

Research Questions

• What is already known about security in Java enabled cell phones?

• Will information stored on a cellular phone be easy to extract?

• How can we secure the stored sensitive information even if the cellular phone is lost or stolen?

• What kind of threats will the cell phone be vulnerable to?

• What kind of countermeasures can be used to reduce or eliminate the threats?

-Problem

Methods

• Literature study– J2ME specifications– Communication link; cell phone ↔ server

• Prototype– Try to break into the prototype

• Security analysis– Identify threats and vulnerabilities

-Methods

Digital safe

• Master password– PIN– Pass-faces– Stored as a SHA1 hash digest

• The sensitive information– AES encrypted with a 128 bit key

• Key derived from master password, username and a iteration count of 20, like described in PKCS5v2 [1]

-Methods

Remote deletion

• SMS sent to the phone with the digital safe installed– Defined port number– The AMS starts the digital safe– SHA1 value of password– Deletes the stored information

-Methods

Stealing MIDlet

• Upgrade a previously installed MIDlet• The RMS will not be erased• Read the stored information• Identical values in the JAD file• Can be used to inject Trojan code

-Methods

Results

• Encryption and decryption– Bouncy Castle Crypto API [2]

• AES, SHA1, …

• Remote deletion is a poor functionality– Can easily be deactivated

• Data stored in the RMS can easily be extracted

-Results

Data extraction

• Forensic methods [3]

– Desoldering techniques, boundary-scan (JTAG)– Native applications

• Windows Mobile, Symbian OS

• Stealing MIDlet• Phone Managers

– Backup of MIDlet’s RMS

-Results

Stealing MIDlet

• Overwrite the installed MIDlet• MIDlet-Name and MIDlet-

Vendor• Source code

– Add Trojan code

• A signed MIDlet can not be upgraded with an unsigned MIDlet!

-Results

A Stealing MIDlet’s JAD file

MIDlet-1: StealingMIDlet,,StealingMIDlet

MIDlet-Jar-Size:

4743

MIDlet-Jar-URL:

StealingMIDlet.jar

MIDlet-Name: Password Store

MIDlet-Vendor:

Tommy Egeberg

MIDlet-Version:

1.0

MicroEdition-Configuration:

CLDC-1.1

MicroEdition-Profile:

MIDP-2.0

Phone Managers

• Oxygen Phone Manager II [4]

– Backup Java MIDlets– Backup MIDlet's RMS

• MOBILedit! [5]

– Forensic edition available

-Results

RMS backup-Results

-Results

Threats & Vulnerabilities

• Information extracted• Trojan code

– Keyboard sniffer, send information to hacker, …

• Phone is stolen• Brute-force attacks• Remote deletion disabled• MIDlet installation request

-Results

Countermeasures

• Reflash cell phone OS• Check MIDlet size and functionality• Sign the MIDlet

– Prevent Stealing MIDlets

• Strong master password and encryption• Frequently update the login credentials

-Results

Conclusion

• A strong master password must be chosen– The key in the encryption process, access to the

application

• Data easily extracted– Encryption extremely important

• The MIDlet should be signed– Prevent installation of Stealing MIDlets, trusted

source

-Conclusion

Further Work

• SATSA (The Security and Trust Service API)• Biometric authentication

– Speech recognition (Java Speech API)

• Proactive password checking• Synchronization service

– Update the stored login credentials if the phone is lost

-Further work

References

[1]RSA-Laboratories. March 1999. Pkcs5v2.0: Password-based cryptography standard.

[2]Bouncy Castle. Bouncy Castle Crypto Package. Light-weight API, release 1.33.

[3] Willassen, S. Y. Spring 2003. Forensics and the GSM mobile telephone system. International Journal of Digital Evidence, 2, 10–11.

[4] Oxygen-Software. Oxygen phone manager for Nokia phones (forensic edition) http://www.opm-2.com

[5] Compelson laboratories. MOBILedit! Forensic http://www.mobiledit.com