  The adoption of processing-in-memory (PiM) architectures has been gaining
momentum because they provide high performance and low energy consumption by
alleviating the data movement bottleneck. Yet, the security of such
architectures has not been thoroughly explored. The adoption of PiM solutions
provides a new way to directly access main memory, which can be potentially
exploited by malicious user applications. We show that this new way to access
main memory opens opportunities for high-throughput timing attack vectors that
are hard-to-mitigate without significant performance overhead.
  We introduce IMPACT, a set of high-throughput main memory-based timing
attacks that leverage characteristics of PiM architectures to establish covert
and side channels. IMPACT enables high-throughput communication and private
information leakage. To achieve this, IMPACT (i) eliminates expensive cache
bypassing steps required by processor-centric main memory and cache-based
timing attacks and (ii) leverages the intrinsic parallelism of PiM operations.
First, we showcase two covert-channel attack variants that run on the host CPU
and leverage PiM architectures to gain direct and fast access to main memory
and establish high-throughput communication covert channels. Second, we
showcase a side-channel attack on a DNA sequence analysis application that
leaks the private characteristics of a user's sample genome by leveraging PiM
operations. Our results demonstrate that (i) our covert channels achieve up to
14.16 Mb/s communication throughput, which is 6.38x faster than the
state-of-the-art main memory-based covert channels, and (ii) our side-channel
attack allows the attacker to determine the properties of a sample genome at a
throughput of 7.5 Mb/s with 96% accuracy. We discuss and evaluate several
countermeasures for IMPACT to enable secure and robust PiM architectures.
