kirillwow/ids_bypass

An issue was discovered in Suricata before 3.1.2. If an ICMPv4 error packet is received as the first packet on a flow in the to_client direction, it confuses the rule grouping lookup logic. The toclient inspection will then continue with the wrong rule group. This can lead to missed detection.

Suricata before 4.0.5 stops TCP stream inspection upon a TCP RST from a server. This allows detection bypass because Windows TCP clients proceed with normal processing of TCP data that arrives shortly after an RST (i.e., they act as if the RST had not yet been received).