This CC practice question tests your understanding of security operations. 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.
Exhibit
Refer to the exhibit.
```
[IDS Alert] Signature: ET TROJAN Win32/SpyEye Checkin
Source IP: 10.10.10.5 -> Destination IP: 203.0.113.50
Time: 2023-03-15 14:32:45
Alert: Priority 1
```
Refer to the exhibit. The IDS alert indicates a possible SpyEye botnet check-in from an internal host. What immediate action should the analyst take?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Isolate the internal host from the network
Isolating the internal host immediately stops the potential command-and-control (C2) communication with the SpyEye botnet, preventing data exfiltration or further compromise. This is the first step in incident response (containment) before any forensic analysis or remediation, as per NIST SP 800-61 guidelines. Delaying containment could allow the botnet to receive new instructions or spread laterally.
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.
✓
Isolate the internal host from the network
Why this is correct
Isolating the host stops the C2 traffic and prevents lateral movement.
Related concept
Read the scenario before looking for a memorised answer.
✗
Ignore the alert as it is a false positive
Why it's wrong here
Priority 1 alerts should not be ignored without investigation.
✗
Block the destination IP at the firewall
Why it's wrong here
Blocking the IP is a good step, but isolating the host is more immediate to contain the threat.
✗
Run a full antivirus scan on the internal host
Why it's wrong here
Scanning is a later step; containment first.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the principle that containment (isolation) must precede remediation (scanning or blocking) in incident response, tricking candidates into choosing a reactive firewall block or a delayed scan instead of immediate host isolation.
Detailed technical explanation
How to think about this question
SpyEye is a known banking trojan that uses HTTP-based C2 check-ins, often mimicking legitimate traffic to evade detection. The IDS alert likely triggered on a signature matching SpyEye's unique HTTP User-Agent string or a specific URI pattern (e.g., /gate.php). Isolating the host via network access control (NAC) or manually disabling its switch port ensures that even if the malware attempts to use alternate C2 IPs or DNS fast-flux, the traffic cannot leave the local subnet.
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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Isolate the internal host from the network — Isolating the internal host immediately stops the potential command-and-control (C2) communication with the SpyEye botnet, preventing data exfiltration or further compromise. This is the first step in incident response (containment) before any forensic analysis or remediation, as per NIST SP 800-61 guidelines. Delaying containment could allow the botnet to receive new instructions or spread laterally.
What should I do if I get this CC question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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