DSAssassin: Cross-VM Side-Channel Attacks by Exploiting Intel Data Streaming Accelerator

Modern datacenter infrastructures increasingly integrate bespoke accelerators to offload specific workloads from CPUs. Among them, Intel's Data Streaming Accelerator (DSA), supported by Intel VT-d, is deployed in the latest Xeon processors. However, its security implications remain unexplored. In this paper, we propose DSAssassin, a novel side-channel attack launched from DSA. Although Intel's scalable I/O virtualization mitigates device-based threats, we show that DSA introduces a new attack surface that bypasses such protections. By reverse-engineering the Device TLB (DevTLB) introduced by DSA, we find that it is not isolated by different processes. We further analyze DSA's shared work queue (SWQ) and uncover a timer-free side channel via DMWr transaction. Building on these insights, we develop two attack primitives: a DevTLB-based timing attack and an SWQ-based contention attack. These enable cross-VM covert- and side-channel attacks. First, the cross-VM covert-channel can achieve a true capability of 17.19 Kbps with a 4.64% error rate—5× faster and 4× more accurate than the latest work. Second, we present a website fingerprinting attack on the top 100 websites, and the classification accuracy can reach 85.7%. Finally, we demonstrate a cross-VM keystroke inference attack with$F_{1}$scores of 92.0% (DevTLB) and 98.4% (SWQ)—outperforming the state-of-the-art.