The answer is unusual outbound connections to unknown IP addresses, as this directly reflects a backdoor Trojan’s primary function of establishing covert command-and-control (C2) channels. A backdoor Trojan, once installed, silently opens a port and initiates outbound traffic to a remote attacker’s server, bypassing typical firewall rules that monitor inbound connections. On the Certified Ethical Hacker CEH exam, this indicator tests your ability to distinguish between general malware symptoms and specific backdoor behaviors—common traps include mistaking high CPU usage alone as definitive, when it is the combination of unexpected outbound traffic and unauthorized processes that confirms a backdoor. Remember the memory tip: “Outbound is the inbound for backdoors”—if you see traffic leaving to an unknown IP, especially on non-standard ports, suspect a Trojan.
CEH Practice Question: Malware, Social Engineering and Network Attacks
This CEH practice question tests your understanding of malware, social engineering and network attacks. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which THREE of the following are indicators that a system may be infected with a backdoor Trojan? (Select three)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Unexpected network traffic on ports typically used for remote administration
Backdoor Trojans often cause unusual network connections to unknown IPs, unexpected outbound traffic, and unauthorized processes running. High CPU usage alone could be other malware, but combined with network activity it's indicative.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Unexpected network traffic on ports typically used for remote administration
Why this is correct
Backdoors often use ports like 4444, 1337 for communication.
Related concept
Read the scenario before looking for a memorised answer.
✗
Persistent high CPU usage by a single process
Why it's wrong here
Could be legitimate or other malware, not specific to backdoors.
✓
Unauthorized processes running in the background
Why this is correct
Backdoors run as hidden processes.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increased number of DNS queries to known legitimate sites
Why it's wrong here
Increased queries to legitimate sites is not typical; backdoors may use DNS tunneling but that's to malicious domains.
✓
Unusual outbound connections to unknown IP addresses
Why this is correct
Backdoors connect to C2 servers, causing outbound connections.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Malware, Social Engineering and Network Attacks — This question tests Malware, Social Engineering and Network Attacks — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Unexpected network traffic on ports typically used for remote administration — Backdoor Trojans often cause unusual network connections to unknown IPs, unexpected outbound traffic, and unauthorized processes running. High CPU usage alone could be other malware, but combined with network activity it's indicative.
What should I do if I get this CEH question wrong?
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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