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Serverless" cloud services, such as AWS lambdas, are one of the fastest growing segments of the cloud services market. These services are popular in part due to their light-weight nature and flexibility in scheduling and cost, however the security issues associated with serverless computing are not well understood. In this work, we explore the feasibility of constructing a practical covert channel from lambdas. We establish that a fast co-residence detection for lambdas is key to enabling such a covert channel, and proceed to develop a reliable and scalable co-residence detector based on the memory bus hardware. Our technique enables dynamic discovery for co-resident lambdas and is incredibly fast, executing in a matter of seconds. We evaluate our approach for correctness and scalability, and use it to establish covert channels and perform data transfer on AWS lambdas. We show that we can establish hundreds of individual covert channels for every 1000 lambdas deployed, and each of those channels can send data at a rate of200 bits per second, thus demonstrating that covert communication via lambdas is entirely feasible. CCS CONCEPTS• Security and privacy → Virtualization and security.

Hardware disaggregation has emerged as one of the most fundamental shifts in how we build computer systems over the past decades. While disaggregation has been successful for several types of resources (storage, power, and others), memory disaggregation has yet to happen. We make the case that the time for memory disaggregation has arrived. We look at past successful disaggregation stories and learn that their success depended on two requirements: addressing a burning issue and being technically feasible. We examine memory disaggregation through this lens and find that both requirements are finally met. Once available, memory disaggregation will require software support to be used effectively. We discuss some of the challenges of designing an operating system that can utilize disaggregated memory for itself and its applications.

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