Analysis of TLS Prefiltering for IDS Acceleration

Network intrusion detection systems (IDS) and intrusion prevention systems (IPS) have proven to play a key role in securing networks. However, due to their computational complexity, the deployment is difficult and expensive. Therefore, many times the IDS is not powerful enough to handle all network traffic on high-speed network links without uncontrolled packet drop. High-speed packet processing can be achieved using many CPU cores or an appropriate acceleration. But the acceleration has to preserve the detection quality and has to be flexible to handle ever-emerging security threats. One of the common acceleration methods among intrusion detection/prevention systems is the bypass of encrypted packets of the Transport Layer Security (TLS) protocol. This is based on the fact that IDS/IPS cannot match signatures in the packet encrypted payload. The paper provides an analysis and comparison of available TLS bypass solutions and proposes a high-speed encrypted TLS Prefilter for further acceleration. We are able to demonstrate that using our technique, the IDS performance has tripled and at the same time detection results have resulted in a lower rate of false positives. It is designed as a software-only architecture with support for commodity cards. However, the architecture allows smooth transfer of the proposed method to the HW-based solution in Field-programmable gate array (FPGA) network interface cards (NICs).