In the wake of all the news regarding the malware in the Android Market, it occurred to me that there isn't a good way to *completely* restore a phone to factory defaults.
First off, great job to Google for removing the malicious apps quickly. The so called "kill switches" in the Android Market and App Store are great features for handling exactly this, and obviate a lot of need for antivirus software. At the end of the CNN article that was slashdotted (http://www.cnn.com/2011/TECH/mobile/03/02/google.malware.andriod/), the author states: "If you've downloaded one of these apps, it might be best to take your device to your carrier and exchange it for a new one, since you can't be sure that your device and user information is truly secure." If my understanding of this malware is correct, it contains an exploit for a kernel privilege escalation vulnerability. Sans all the discussion on this mailing list regarding forcing OEMs to push security updates, there is still the possibility of a zero-day kernel exploit. Which leads me to the premise of this email: Android lets me wipe all user data, i.e., "restore to factory settings", via the user interface (or by rebooting to recovery mode), but how do I restore the "system" partition? Currently, the Google OTA's are frequently patches (which is great to save bandwidth). However, these links are only public once someone (e.g., on XDA) discovers and posts them. If my understanding of this is correct, there are also "full" OTA images out there. I'm not sure of the best way to achieve this goal, but it would be beneficial for a user to restore the system partition to a known state as well, without the need to take the phone to a cell provider store. (I recall the T-Mobile G2 having an anti-jailbreak mechanism that would potentially accomplish at least part of this). Thoughts? There are some interesting trade-offs when defining the threat model for a solution (e.g., do we trust the recovery image hasn't been modified). Thanks, -Will -- William Enck PhD Researcher Department of Computer Science and Engineering The Pennsylvania State University [email protected] -- You received this message because you are subscribed to the Google Groups "Android Security Discussions" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/android-security-discuss?hl=en.
