Poster: A Fast Monitor for Slow Network Attacks

Recent work has demonstrated how programmable switches can effectively detect attack traffic, such as denial-of- service attacks in the midst of high-volume network traffic. However, these techniques primarily rely on sampling- or sketch- based data structures that can only be used to approximate the characteristics of dominant flows in the network. As a result, such techniques are unable to effectively detect slow attacks such as SYN port scans, SSH brute forcing, or HTTP connection exploits, which do so by stealthily adding only a few packets to the network. In this work we explore how the combination of programmable switches, Smart network interface cards (sNICs), and hosts can enable fine-grained analysis of every flow in a cloud network, even those with only a small number of packets. We focus on analyzing packets at the start of each flow, as those packets often can help indicate whether a flow is benign or suspicious, e.g., by detecting an attack which fails to complete the TCP handshake in order to waste server connection resources. Our approach leverages the high-speed processing of a programmable switch while overcoming its primary limitation - very limited memory capacity - by judiciously sending some state for processing to the
$\text{sNIC}$
or the host which typically has more memory, but lower bandwidth. Achieving this requires careful design of data structures on the switch, such as a bloom filter and flow logs, and communication protocols between the switch,
$\text{sNIC}$
, and host, to coordinate state.