CAPEC-326: TCP Initial Window Size Probe
This OS fingerprinting probe checks the initial TCP Window size. TCP stacks limit the range of sequence numbers allowable within a session to maintain the "connected" state within TCP protocol logic. The initial window size specifies a range of acceptable sequence numbers that will qualify as a response to an ACK packet within a session. Various operating systems use different Initial window sizes. The initial window size can be sampled by establishing an ordinary TCP connection.
Overview
CAPEC-326 (TCP Initial Window Size Probe) is a detailed-level attack pattern catalogued by MITRE in the Common Attack Pattern Enumeration and Classification (CAPEC). It describes a recurring method attackers use to exploit software weaknesses.