TCP (ISN) Sequence Predictability Probe
Attack Pattern ID: 324 (Detailed Attack Pattern)Typical Severity: LowStatus: Draft
+ Description

Summary

This type of operating system probe attempts to determine an estimate for how predictable the sequence number generation algorithm is for a remote host. Statistical techniques, such as standard deviation, can be used to determine how predictable the sequence number generation is for a system. This result can then be compared to a database of operating system behaviors to determine a likely match for operating system and version.

+ Target Attack Surface

Target Attack Surface Description

Targeted OSI Layers: Transport Layer

Target Attack Surface Localities

Server-side

Target Attack Surface Types: Host

Target Functional Services

Target Functional Service 1: None
Protocol 1: TCP
Protocol Header 1
Protocol Field NameProtocol Field DescriptionProtocol Data
Sequence Number
The sequence number of the first data octet in a segment (except when a SYN flag is present). If SYN is present the sequence number is the initial sequence number (ISN) of the connection and the first data octet is ISN+1. The sequence number consists of 32 bits.
For purposes of Sequence number analysis the data portion of the packet is either empty or ignored.
Related Protocol: Internet Protocol
Relationship Type
Uses Protocol
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
ChildOfAttack PatternAttack Pattern315TCP/IP Fingerprinting Probes 
Mechanism of Attack (primary)1000
+ References
Stuart McClure, Joel Scambray and George Kurtz. "Hacking Exposed: Network Security Secrets & Solutions". 6th Edition. McGraw Hill, ISBN: 978-0-07-161374-3. 2009.
Defense Advanced Research Projects Agency (DARPA). "RFC793 - Transmission Control Protocol". 1981. <http://www.faqs.org/rfcs/rfc793.html>.
Gordon "Fyordor" Lyon. "Nmap Network Scanning: The Official Nmap Project Guide to Network Discovery and Security Scanning". 3rd "Zero Day" Edition, . Insecure.com LLC, ISBN:978-0-9799587-1-7. 2008.
Gordon "Fyordor" Lyon. "The Art of Port Scanning". Volume: 7, Issue. 51. Phrack Magazine. 1997. <http://nmap.org/p51-11.html>.
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