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RIFLE: User Centric Information Flow Security

I went to a talk yesterday about RIFLE: An Architectural Framework for User-Centric Information-Flow Security, one of a series of University of Colorado CS Colloquia. “User-Centric Information-Flow Security” (UCIFS) is a different way of enforcing security than almost anything I’ve encountered before. Basically, instead of assigning permissions to users and actions, a la JAAS, you assign levels of security to data. This security level is then tracked throughout the application, and at various endpoints (I/O activity, network transmission) a policy is enforced. Therefore, you could tag a SSN with a high security level, and any variables and decisions based on the SSN would be tagged similarly, since security levels propagate. Then, when some piece of malware tries to send your SSN (or anything related to it) off to Russia, the system intervenes.

I say UCIFS is a “different way of enforcing security than almost anything I’ve encountered” above because there’s one thing that I’ve seen that does assign a security level to some kinds of data: perl’s taint mode. I’ve used taint mode in perl cgi scripts before, and it’s a good way to make sure that untrusted data is not used in dangerous situations without the programmer’s explicit knowledge.

However, UCIFS aims a bit higher. An ideal system tracks data and its levels through all algorithms, doesn’t leak data, requires no effort from a programmer and enforces policies dynamically. According to the presenter, it turns out that no system can have zero data leakage. You can always signal the state of a variable in some way, even if it’s as crude as ceasing the operation of the program–these are called ‘covert channels’. RIFLE meets the other criteria, apparently, and does so by operating on binaries and tracking the data via extra registers (I’m on thin ice here, since I’m by no means a systems programmer).

It was an interesting talk because tracking security based on data, and giving users choices for data security, sure seems a better way of dealing with security issues than the program level trust that firewalls and ACLs now provide. Not a whole lot of real world applicability just yet (creating policies was barely touched upon, for one thing), but perhaps in the future. For more, please check out the Liberty Research Group’s website.