Hardware Side Channels in the Cloud

Summary: At REcon 2015, a researcher demonstrated a hardware side channel that targets co-located virtual machines in the cloud by exploiting the CPU's execution pipeline rather than cache tiers. The attack records out-of-order execution artifacts from shared pipeline resources, and by injecting mfence memory barriers a colluding process can force a strong memory order and send a binary message through the resulting change in recorded averages.
Why it matters: The pipeline cannot distinguish one virtual machine's instructions from the hundreds of other alien virtual machines sharing the same physical server, so co-residency alone is enough to leak private crypto keys or establish a covert channel between tenants.

Read the original at Trail of Bits Blog ↗