hardMultiple Choice
ISC2 CC Practice Question: Refer to the exhibit
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?
⚠ Common exam trap
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.
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 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.
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 internal host immediately severs command-and-control traffic to the SpyEye infrastructure, containing potential data exfiltration or further malware propagation while forensic investigation proceeds. It is the fastest containment step for a confirmed botnet check-in alert.
- ✗
Ignore the alert as it is a false positive
Why it's wrong here
Dismissing the alert assumes the traffic is benign without any triage, leaving a potentially SpyEye-infected host beaconing to its controller. False-positive closure is legitimate only after verifying the signature against known-good traffic; here the exhibit shows a botnet check-in pattern that warrants investigation, not suppression.
- ✗
Block the destination IP at the firewall
Why it's wrong here
Blocking the destination IP stops this single check-in but leaves the infected internal host communicating with the botnet's other command-and-control servers. Firewall blocks are tempting for containing known malicious infrastructure, yet the immediate priority is isolating the compromised endpoint, since SpyEye will simply fail over to alternate addresses.
- ✗
Run a full antivirus scan on the internal host
Why it's wrong here
A full antivirus scan is slow and signature-based, leaving the host communicating with the botnet command-and-control server throughout, so containment is delayed. It tempts because scanning is a familiar remediation step, and would be correct after the host is isolated, once active exfiltration has been stopped.
Go deeper
Related to this question
Learn chapter
Access Control Fundamentals
Key term
IDS
An IDS is a security system that monitors network or system traffic for suspicious activity and alerts administrators to potential threats, but does not actively block them.
Key term
Incident
An incident is a security event that violates an organization's policies or threatens its data, systems, or operations, requiring a structured response.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CC practice question is part of Courseiva's free ISC2 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 CC exam.