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ISC2 CC A SOC analyst for a financial institution Practice Question
You are a SOC analyst for a financial institution. At 2:00 AM, your SIEM generates a critical alert from the email security gateway indicating that an internal user received a phishing email with a malicious attachment. The email was delivered to the user's inbox, and the user's account activity logs show that the attachment was opened 10 minutes ago. The user is a junior accountant who works in the accounts payable department. You have access to endpoint detection tools, email logs, and network traffic data. The organization's incident response policy requires containment within 30 minutes of detection. Which action should you take FIRST?
⚠ Common exam trap
ISC2 often tests the principle that containment must happen before any eradication or recovery steps, so candidates mistakenly choose scanning or blocking the sender because they focus on the email vector rather than the active compromise on the endpoint.
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 user's workstation from the network to prevent lateral movement.
The incident response policy requires containment within 30 minutes. Isolating the workstation (e.g., via network access control or disabling the switch port) immediately stops any ongoing malicious activity, such as command-and-control communication or lateral movement, which is the highest priority after detection. This aligns with the NIST SP 800-61 containment strategy and the SANS PICERL model, where containment precedes eradication and recovery.
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 user's workstation from the network to prevent lateral movement.
Why this is correct
Isolation contains the incident quickly, as per policy.
- ✗
Scan the user's workstation with antivirus software.
Why it's wrong here
Scanning is analysis, not containment, and may miss advanced malware.
- ✗
Block the sender's email address at the email gateway.
Why it's wrong here
This prevents future emails but does not address the already-opened attachment.
- ✗
Send an email to the user instructing them to delete the email.
Why it's wrong here
This is not immediate containment; the user may not see the email or may not act promptly.
Go deeper
Related to this question
Learn chapter
Introduction to Security Principles
Key term
SOC
A Security Operations Center (SOC) is a centralized team that monitors, detects, analyzes, and responds to cybersecurity incidents to protect an organization's information systems.
Key term
Alert
An alert is a notification that something unusual or potentially harmful has happened in a computer system or network.
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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.