CAPEC-320 TCP Timestamp Probe

This OS fingerprinting probe examines the remote server's implementation of TCP timestamps. Not all operating systems implement timestamps within the TCP header, but when timestamps are used then this provides the attacker with a means to guess the operating system of the target. The attacker begins by probing any active TCP service in order to get response which contains a TCP timestamp. Different Operating systems update the timestamp value using different intervals. This type of analysis is most accurate when multiple timestamp responses are received and then analyzed. TCP timestamps can be found in the TCP Options field of the TCP header.

1. [Explore] [Determine if timestamps are present.] The adversary sends a probe packet to the remote host to identify if timestamps are present. 2. [Experiment] [Record and analyze timestamp values.] If the remote host is using timestamp, obtain several timestamps, analyze them and compare them to known values.

• The ability to monitor and interact with network communications.Access to at least one host, and the privileges to interface with the network interface card.The target OS must support the TCP timestamp option in order to obtain a fingerprint.

• Confidentiality: Read Data • Confidentiality, Access Control, Authorization: Bypass Protection Mechanism