CompTIA Security Plus Mock Test Q722

An administrator has to determine host operating systems on the network and has deployed a transparent proxy. Which of the following fingerprint types would this solution use?

A. Packet
B. Active
C. Port
D. Passive


Correct Answer: D
Section: Threats and Vulnerabilities

Explanation:
TCP/IP stack fingerprinting is the passive collection of configuration attributes from a remote device during standard layer 4 network communications. The combination of parameters
may then be used to infer the remote machine’s operating system (aka, OS fingerprinting), or incorporated into a device fingerprint.
Certain parameters within the TCP protocol definition are left up to the implementation. Different operating systems and different versions of the same operating system set different
defaults for these values. By collecting and examining these values, one may differentiate among various operating systems, and implementations of TCP/IP. Just inspecting the Initial
TTL and window size TCP/IP fields is often enough in order to successfully identify an operating system, which eases the task of performing manual OS fingerprinting.
Passive OS fingerprinting is the examination of a passively collected sample of packets from a host in order to determine its operating system platform. It is called passive because it
doesn’t involve communicating with the host being examined.
In this question, the proxy will use passive fingerprinting because the proxy is a ‘transparent proxy’. It isn’t seen by the computer.

Incorrect Answers:
A: Active or Passive fingerprinting can both be called packet fingerprinting because the OS is learned from the TCP/IP packets. However, ‘packet fingerprinting’ is not a specific term
for OS fingerprinting. The other answers are more specific about the type of fingerprinting used.
B: Active fingerprinting involves sending packets to the target system and examining the response. This method is not used with transparent proxies.
C: Port fingerprinting is not a method used to discover the operating system of a computer.

References:
https://en.wikipedia.org/wiki/TCP/IP_stack_fingerprinting
http://www.windowsecurity.com/articles-tutorials/intrusion_detection/Operating-System-Fingerprinting-Packets-Part1.html