Hardware security features need to strike a careful balance between design intrusiveness and completeness of methods. Securing against attacks like Return Oriented Programming (ROP) requires frequent and expensive checks. Complete security defenses have been proposed yet modern systems are still vulnerable to ROP attacks. We provide complete security by decomposing the solution into two stages. The first stage raises alarms based on an imprecise, low cost hardware detector. The second stage applies complete methods in order to accurately distinguish real attacks from false alarms. This decomposition is enabled with Record and Deterministic Replay. The original execution is recorded and subjected to replay analysis as alarms are raised. In this way the Replay infrastructure can compensate for the occasional hardware imprecision.
We demonstrate this approach by applying it to thwart ROP attacks on the Linux kernel. We call the design RnR-ROPSafe. It reuses a simple Return Address Stack (RAS) as the hardware detector. The RAS is slightly modified to prevent corruption of the RAS due to multithreading and due to non-procedural returns—improving its performance as a ROP detector. Rare false positives due to underflows are eliminated via replay instead of hardware over-design. RnR-ROPSafe relies on two on-the-fly replayers: an always-on, fast Checkpointing replayer that periodically creates checkpoints, and a detailed-analysis Alarm replayer that is triggered when there is a threat alarm. We find that the first one has execution speed comparable to that of the recorder, and can be replaying all the time, while the latter has to handle only very few false positives
