- A
Reimage the server immediately to ensure the malware is completely removed.
Why wrong: Reimaging destroys forensic evidence and may not be necessary if a less destructive approach is available.
- B
Uninstall the current antivirus and install a different endpoint protection solution, then perform a full scan.
Why wrong: This takes time and does not prevent ongoing data exfiltration; isolation is more urgent.
- C
Delete the 'UpdateSvc' service and the 'HealthCheck' scheduled task, then run a full antivirus scan.
Why wrong: This may destroy evidence and the malware could have additional persistence mechanisms.
- D
Isolate the server from the network by disconnecting the network cable and blocking the IP at the firewall, then initiate incident response procedures.
Isolation stops the attack and preserves evidence for investigation.
Quick Answer
The answer is to isolate the server from the network by disconnecting the network cable and blocking the C2 IP at the firewall. This is correct because the immediate priority in incident response containment steps is to stop active data exfiltration and command-and-control communication; disconnecting the cable cuts the physical link, while blocking the IP at the firewall prevents any further outbound traffic on TCP port 8443, halting the malicious scheduled task from downloading additional payloads. On the Certified Ethical Hacker CEH exam, this scenario tests your ability to prioritize containment over analysis or remediation—a common trap is to jump to deleting the service or scheduled task, which could alert the attacker and destroy volatile evidence. Remember the CEH incident response mantra: "Contain before you clean, isolate before you investigate." Memory tip: think "Cable and C2"—the fastest way to stop a live breach is to cut the wire and block the call.
CEH Cryptography and Malware Analysis Practice Question
This CEH practice question tests your understanding of cryptography and malware analysis. 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.
You are a security analyst at a financial institution. The SOC has detected anomalous outbound traffic from a server in the DMZ to an unknown IP address on TCP port 8443. The server runs a custom application that normally communicates with internal databases on port 1433. The server's OS is Windows Server 2019. Preliminary analysis shows that a new service named 'UpdateSvc' was installed three days ago, set to start automatically, and runs under the LocalSystem account. The service binary is located at C:\Windows\System32\svchost.exe (the legitimate one). However, the service's 'ImagePath' registry key points to 'C:\Windows\System32\svchost.exe -k UpdateSvc'. Additionally, a scheduled task named 'HealthCheck' runs every hour and executes 'powershell.exe -EncodedCommand <base64>'. The encoded command decodes to a script that downloads a payload from the same unknown IP on port 8443 and executes it in memory. The server has antivirus installed that detected nothing. As the analyst, which of the following is the BEST immediate course of action?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Isolate the server from the network by disconnecting the network cable and blocking the IP at the firewall, then initiate incident response procedures.
Option D is correct because the immediate priority is to contain the threat by isolating the compromised server from the network (disconnecting the cable) and blocking the command-and-control IP at the firewall. This stops the ongoing outbound communication on TCP port 8443 and prevents further payload downloads or data exfiltration. Initiating incident response procedures ensures proper forensic collection and analysis, which is critical before any remediation steps like reimaging or deleting artifacts.
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.
- ✗
Reimage the server immediately to ensure the malware is completely removed.
Why it's wrong here
Reimaging destroys forensic evidence and may not be necessary if a less destructive approach is available.
- ✗
Uninstall the current antivirus and install a different endpoint protection solution, then perform a full scan.
Why it's wrong here
This takes time and does not prevent ongoing data exfiltration; isolation is more urgent.
- ✗
Delete the 'UpdateSvc' service and the 'HealthCheck' scheduled task, then run a full antivirus scan.
Why it's wrong here
This may destroy evidence and the malware could have additional persistence mechanisms.
- ✓
Isolate the server from the network by disconnecting the network cable and blocking the IP at the firewall, then initiate incident response procedures.
Why this is correct
Isolation stops the attack and preserves evidence for investigation.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates focus on removing the malware artifacts (service and task) rather than containing the threat first, which is a fundamental incident response principle: isolate before eradicate.
Detailed technical explanation
How to think about this question
The malware uses a technique called 'living off the land' by abusing the legitimate svchost.exe with a custom service group (-k UpdateSvc) to appear benign. The PowerShell encoded command executes a fileless payload entirely in memory, bypassing traditional antivirus that relies on disk-based signatures. In real-world scenarios, such as the 2020 SolarWinds attack, similar fileless persistence and C2 communication on non-standard ports (like 8443) were used to evade detection for months.
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.
TExam Day Tips
- 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 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.
What to study next
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FAQ
Questions learners often ask
What does this CEH question test?
Cryptography and Malware Analysis — This question tests Cryptography and Malware Analysis — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Isolate the server from the network by disconnecting the network cable and blocking the IP at the firewall, then initiate incident response procedures. — Option D is correct because the immediate priority is to contain the threat by isolating the compromised server from the network (disconnecting the cable) and blocking the command-and-control IP at the firewall. This stops the ongoing outbound communication on TCP port 8443 and prevents further payload downloads or data exfiltration. Initiating incident response procedures ensures proper forensic collection and analysis, which is critical before any remediation steps like reimaging or deleting artifacts.
What should I do if I get this CEH question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This CEH practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CEH exam.
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