A skilled ethical hacker was assigned to perform a thorough OS discovery on a potential...

ECCouncil 312-50v13 Question Answer

A skilled ethical hacker was assigned to perform a thorough OS discovery on a potential target. They decided to adopt an advanced fingerprinting technique and sent a TCP packet to an open TCP port with specific flags enabled. Upon receiving the reply, they noticed the flags were SYN and ECN-Echo. Which test did the ethical hacker conduct and why was this specific approach adopted?

Test 3: The test was executed to observe the response of the target system when a packet with URG, PSH, SYN, and FIN flags was sent, thereby identifying the OS

Qrest 1: The test was conducted because SYN and ECN-Echo flags enabled to allow the hacker to probe the nature of the response and subsequently determine the OS fingerprint

Test 2: This test was chosen because a TCP packet with no flags enabled is known as a NULL packet and this would allow the hacker to assess the OS of the target

Test 6; The hacker selected this test because a TCP packet with the ACK flag enabled sent to a closed TCP port would yield more information about the OS

Explanation:

The ethical hacker conducted Test 1, which is a TCP/IP stack fingerprinting technique that uses the SYN and ECN-Echo flags to determine the OS of the target system. The SYN flag is used to initiate a TCP connection, and the ECN-Echo flag is used to indicate that the sender supports Explicit Congestion Notification (ECN), which is a mechanism to reduce network congestion. Different OSes have different implementations and responses to these flags, which can reveal their identity. For example, Windows XP and 2000 will reply with SYN and ECN-Echo flags set, while Linux will reply with only SYN flag set. By sending a TCP packet with these flags enabled to an open TCP port and observing the reply, the ethical hacker can probe the nature of the response and subsequently determine the OS fingerprint.

The ethical hacker adopted this specific approach because it is an advanced and stealthy technique that can evade some firewalls and intrusion detection systems (IDS) that may block or alert other types of packets, such as NULL, FIN, or Xmas packets. Moreover, this technique can provide more accurate and reliable results than other techniques, such as banner grabbing or passive analysis, that may depend on the availability or validity of the information provided by the target system.

The other options are not correct, as they describe different tests and reasons. Test 3 is a TCP/IP stack fingerprinting technique that uses the URG, PSH, SYN, and FIN flags to determine the OS of the target system. Test 2 is a TCP/IP stack fingerprinting technique that uses a NULL packet, which is a TCP packet with no flags enabled, to determine the OS of the target system. Test 6 is a TCP/IP stack fingerprinting technique that uses the ACK flag, which is used to acknowledge the receipt of a TCP segment, to determine the OS of the target system. References:

OS and Application Fingerprinting | SANS Institute

Operating System Fingerprinting | SpringerLink

OS and Application Fingerprinting - community.akamai.com

What is OS Fingerprinting and Techniques - Zerosuniverse

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