Information Flow Control for Intrusion Detection Derived from MAC Policy

Most of today's MAC implementations can be turned into permissive mode, where no enforcement is performed but alerts are raised instead. This behavior is very close to an anomaly IDS except that the system is configured through a MAC policy. MAC implementations such as SELinux and AppArmor come with a default policy including real life and practical rules ready to be used as is or as a basis for a custom policy. In this paper, we first propose an extension of an IDS based on information flow control. We address issues concerning programs execution and improve its expressiveness in terms of security policy. This extended model can be configured to reach a wide variety of different security goals. Particularly, it allows for information flow checking based on users and/or programs dependent policy rules. Furthermore, suspicious modification of binary programs can be detected to avoid malware execution. We also propose an algorithm for deriving an AppArmor MAC policy into an information flow policy, and thus get the advantage of having a ready to use policy offering good security. We finally show a practical example of deriving such a policy in order to configure our IDS.