GCFA Practice Question: Identification of Malicious and Normal Activity
An analyst observes a high volume of '4625' events for a single user account. What does this indicate and what is the appropriate initial response?
⚠ Common exam trap
Test-takers frequently mistake Event ID 4625 for successful logons or treat it purely as an informational alert, overlooking the critical need for immediate containment like account locking.
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
✓
Indicates a brute-force attack; lock the account and investigate.
Event ID 4625 indicates failed logon attempts. A high volume often suggests a brute-force or password-spraying attack. The immediate response should be to isolate the account and investigate the source of the failures to prevent unauthorized access. This is a baseline security operation that every analyst must perform, as it is the most common indicator of credential-based attacks currently plaguing enterprise network environments.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Indicates a successful system update; no action required.
Why it's wrong here
Event ID 4625 is unequivocally a failed logon attempt. Suggesting it indicates a system update is fundamentally incorrect and dangerous. Misinterpreting failed authentication events as routine system maintenance will lead to ignoring active brute-force attempts and potentially allowing an attacker to gain unauthorized access to the environment.
- ✓
Indicates a brute-force attack; lock the account and investigate.
Why this is correct
A high volume of 4625 events signifies repeated failed authentication attempts, which is the textbook definition of a brute-force or password-spraying attack. Locking the account and investigating the source IP is the standard and necessary incident response procedure to mitigate the risk of credential compromise in this scenario.
- ✗
Indicates a malware infection; format the hard drive.
Why it's wrong here
Formatting a drive is a destructive action that destroys forensic evidence without addressing the immediate threat. A series of failed logins is an authentication issue, not direct proof of malware. Proper analysis requires investigating the source of the attempts, not resorting to extreme measures that prevent further investigation.
- ✗
Indicates a network failure; check the cabling.
Why it's wrong here
Network failures do not generate 4625 authentication failure events. This event is generated by the local security authority when an authentication request fails. Suggesting a physical layer check for a logical authentication error demonstrates a fundamental misunderstanding of Windows authentication logs and how to troubleshoot security events effectively.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official GIAC exam blueprint
This GCFA practice question is part of Courseiva's free GIAC 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 GCFA exam.