CEH Practice Question: Malware, Social Engineering and Network Attacks
This CEH practice question tests your understanding of malware, social engineering and network attacks. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An analyst observes the following output from Wireshark: a TCP packet with the SYN flag set, followed by a SYN-ACK, then an ACK, and then a RST. The sequence numbers show a pattern: initial seq=100, ack=300, then seq=300, ack=101. What is the MOST likely interpretation?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
An attacker is performing TCP sequence prediction to hijack the session.
The sequence numbers (100, 300) suggest the attacker correctly guessed the TCP sequence numbers to spoof a connection. The three-way handshake completes (SYN, SYN-ACK, ACK), then the attacker sends a RST to close. This is indicative of TCP sequence prediction attack (session hijacking attempt).
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
An attacker is performing TCP sequence prediction to hijack the session.
Why this is correct
Correct. The sequence numbers show successful prediction, and the RST may be used to reset the connection after hijacking.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
A normal TCP connection establishment followed by an immediate termination.
Why it's wrong here
While a RST after handshake can occur, the sequence number pattern is suspicious.
✗
A man-in-the-middle attack using ARP spoofing.
Why it's wrong here
ARP spoofing would not be directly observed as TCP sequence numbers in Wireshark.
✗
A TCP SYN flood attack is in progress.
Why it's wrong here
SYN flood involves many SYN packets without completing the handshake.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CEH NAT questions on configuration and troubleshooting.
Malware, Social Engineering and Network Attacks — This question tests Malware, Social Engineering and Network Attacks — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: An attacker is performing TCP sequence prediction to hijack the session. — The sequence numbers (100, 300) suggest the attacker correctly guessed the TCP sequence numbers to spoof a connection. The three-way handshake completes (SYN, SYN-ACK, ACK), then the attacker sends a RST to close. This is indicative of TCP sequence prediction attack (session hijacking attempt).
What should I do if I get this CEH question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CEH NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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