CHFI OS and Network Forensics Practice Question
A security analyst is reviewing Windows Event Logs and notices multiple Event ID 4625 entries for a single user account within a short time frame. What does this most likely indicate?
⚠ Common exam trap
Many exam-takers confuse Event ID 4625 (failed logon) with Event ID 4624 (successful logon) or assume any repeated event indicates a system error rather than an active attack.
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
✓
A brute-force password guessing attack
Event ID 4625 is the Windows security log event for a failed logon attempt. A high frequency of these events for the same user account within a short time frame is a classic indicator of an automated brute-force password guessing attack, where an attacker tries multiple passwords against a single account.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Successful user logins
Why it's wrong here
A successful user logon generates Event ID 4624 (An account was successfully logged on), not 4625. Event ID 4625 is specifically reserved for failed logon attempts and is raised when authentication fails due to bad credentials, disabled accounts, or locked accounts. Thus, a high volume of 4625 events cannot be attributed to successful user activity, as that would produce a different event ID with a different logon outcome.
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Account creation events
Why it's wrong here
Account creation in Windows is tracked as a Security event ID 4720 (A user account was created), which belongs to the Account Management audit category. Event ID 4625, by contrast, belongs to the Logon/Logoff audit category and indicates an authentication failure for an existing account. While an attacker might create a new account and then attempt to log on with it, the creation event itself would not appear as 4625; the absence of 4720 events in the log points away from account provisioning.
- ✓
A brute-force password guessing attack
Why this is correct
A brute-force password guessing attack is characterized by a high volume of Event ID 4625 (failed logon) records in a short window, often for the same target user account, and frequently originating from multiple source IP addresses or repeated attempts with varying passwords. The Failure Reason on these events typically shows 'Unknown user name or bad password' (status code 0xC000006D) or 'the specified account's password has expired' when lockout policies exist. This pattern is the classic signature of an automated tool cycling through passwords, making it the correct interpretation of a surge in 4625 events.
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Service installation
Why it's wrong here
Service installation on Windows is recorded in the System log as Event ID 7045 (A service was installed in the system), not in the Security log. Event ID 4625 is a Security log event signifying a failed authentication attempt; installing a service does not inherently cause a logon failure. While a malicious service might later run as a user and generate 4625 events if it tries to authenticate with bad credentials, that would be an indirect consequence, and the 7045 event would be the primary indicator—not the 4625 flood seen here.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CHFI 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 CHFI exam.