CHFI OS and Network Forensics Practice Question
A security analyst observes multiple Event ID 4625 logon failures for a single user account within a short time frame, followed by Event ID 4624 logon success. Which attack technique is MOST likely indicated?
⚠ Common exam trap
EC-CHFI often tests the distinction between pre-authentication attacks (brute-force, password spraying) and post-authentication attacks (pass-the-hash, golden ticket), where candidates mistakenly associate any successful logon after failures with a hash-based attack instead of recognizing the sequential failure-success pattern as brute-force.
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
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Brute-force or password spraying attack
Event ID 4625 indicates failed logon attempts, and Event ID 4624 indicates a successful logon. A rapid sequence of failures followed by a success for the same user account is the classic signature of a brute-force or password spraying attack, where an attacker tries multiple passwords until one works. This pattern is specific to authentication attempts against the local SAM or domain controller via NTLM or Kerberos, not to post-authentication attacks.
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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Kerberos golden ticket attack
Why it's wrong here
A Kerberos golden ticket attack forges a TGT using the compromised KRBTGT account hash, so no password attempt occurs. Successful use appears as 4624 logon events with authentication package Kerberos, not a stream of 4625 failure codes. The attacker impersonates a privileged user by signing a forged ticket rather than guessing credentials, making multiple failed logons the wrong artifact.
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SQL injection attack on the authentication database
Why it's wrong here
SQL injection against an authentication database manipulates SQL queries at the application layer and cannot trigger Windows LSA logon events. Event ID 4625 is created by the Local Security Authority only when a logon attempt hits the Windows security subsystem, independent of any SQL backend. An attacker who compromises the DB may steal password hashes but would not produce repeated 4625 audit failures, which require a real credential validation attempt against the OS.
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Brute-force or password spraying attack
Why this is correct
The correct finding: a burst of 4625 events followed by a 4624 event is the canonical signature of brute-force or password-spraying. Brute-force creates many failed attempts per target account with different passwords, while spraying uses one password across many accounts; both generate numerous 4625 audit records. When one guess finally matches, a 4624 success appears, confirming the attack succeeded.
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Pass-the-hash attack
Why it's wrong here
Pass-the-hash reuses a captured NTLM hash to authenticate without knowing or trying passwords, so it does not generate repeated 4625 failures. The attack produces a single successful 4624 event, typically Logon Type 3 (network) or 10 (remote interactive), using a forged or stolen hash. If an attacker attempts an invalid hash, you might see one 4625, but a pattern of many failed logons is not the PtH signature.
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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.