Hardware security features need to strike a careful balance between design intrusiveness and completeness of methods. In addition, they need to be flexible, as security threats continuously evolve. To help address these requirements, this paper proposes a novel framework where Record and Deterministic Replay (RnR) is used to complement hardware security features. We call the framework RnR-Safe. RnR-Safe reduces the cost of security hardware by allowing it to be less precise at detecting attacks, potentially reporting false positives. This is because it relies on on-the-fly replay that transparently verifies whether the alarm is a real attack or a false positive. RnR-Safe uses two replayers: an always-on, fast Checkpoint replayer that periodically creates checkpoints, and a detailed-analysis Alarm replayer that is triggered when there is a threat alarm. As an example application, we use RnR-Safe to thwart Return Oriented Programming (ROP) attacks, including on the Linux kernel. Our design augments the Return Address Stack (RAS) with relatively inexpensive hardware. We evaluate RnR-Safe using a variety of workloads on virtual machines running Linux. We find that RnR-Safe is very effective. Thanks to the judicious RAS hardware extensions and hypervisor changes, the checkpointing replayer has an execution speed comparable to the recorded execution. Also, the alarm replayer needs to handle very few false positives.

Cache-based covert channel attacks use highly-tuned shared-cache conflict misses to pass information from a trojan to a spy process. Detecting such attacks is very challenging. State of the art detection mechanisms do not consider the general characteristics of such attacks and, instead, focus on specific communication protocols. As a result, they fail to detect attacks using different protocols and, hence, have limited coverage. In this paper, we make the following observation about these attacks: not only are the malicious accesses highly tuned to the mapping of addresses to the caches; they also follow a distinctive cadence as bits are being received. Changing the mapping of addresses to the caches substantially disrupts the conflict miss patterns, but retains the cadence. This is in contrast to benign programs. Based on this observation, we propose a novel, high-coverage approach to detect cache-based covert channel attacks. It is called ReplayConfusion, and is based on Record and deterministic Replay (RnR). After a program's execution is recorded, it is deterministically replayed using a different mapping of addresses to the caches. We then analyze the difference between the cache miss rate timelines of the two runs. If the difference function is both sizable and exhibits a periodic pattern, it indicates that there is an attack. This paper also introduces a new taxonomy of cache-based covert channel attacks, and shows that ReplayConfusion uncovers examples from all the categories. Finally, ReplayConfusion only needs simple hardware.