This OS fingerprinting probe tests the target system's assignment of TCP sequence numbers. One common way to test TCP Sequence Number generation is to send a probe packet to an open port on the target and then compare the how the Sequence Number generated by the target relates to the Acknowledgement Number in the probe packet. Different operating systems assign Sequence Numbers differently, so a fingerprint of the operating system can be obtained by categorizing the relationship between the acknowledgement number and sequence number as follows: 1) the Sequence Number generated by the target is Zero, 2) the Sequence Number generated by the target is the same as the acknowledgement number in the probe, 3) the Sequence Number generated by the target is the acknowledgement number plus one, or 4) the Sequence Number is any other non-zero number.
Likelihood Of Attack
This table shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
Standard Attack Pattern - A standard level attack pattern in CAPEC is focused on a specific methodology or technique used in an attack. It is often seen as a singular piece of a fully executed attack. A standard attack pattern is meant to provide sufficient details to understand the specific technique and how it attempts to accomplish a desired goal. A standard level attack pattern is a specific type of a more abstract meta level attack pattern.
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.
A tool capable of sending and receiving packets from a remote system.
This table specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Bypass Protection Mechanism
A Related Weakness relationship associates a weakness with this attack pattern. Each association implies a weakness that must exist for a given attack to be successful. If multiple weaknesses are associated with the attack pattern, then any of the weaknesses (but not necessarily all) may be present for the attack to be successful. Each related weakness is identified by a CWE identifier.
Exposure of Sensitive Information to an Unauthorized Actor
[REF-33] Stuart McClure, Joel Scambray
and George Kurtz. "Hacking Exposed: Network Security Secrets & Solutions". Chapter 2: Scanning, pg. 55-56. 6th Edition. McGraw Hill. 2009.
[REF-128] Defense Advanced Research Projects Agency Information Processing Techniques Office and
Information Sciences Institute University of Southern California. "RFC793 - Transmission Control Protocol". Defense Advanced Research Projects Agency (DARPA). 1981-09.
[REF-212] Gordon "Fyodor" Lyon. "Nmap Network Scanning: The Official Nmap Project Guide to Network Discovery and Security Scanning". Chapter 8. Remote OS Detection. 3rd "Zero Day" Edition,. Insecure.com LLC. 2008.