CS0-003 Security Operations Practice Question
A security analyst is reviewing a SIEM alert that triggered on a single failed login attempt from an internal IP address. The username used does not exist in Active Directory. The analyst checks the source IP and finds it belongs to a known vulnerability scanner. What classification should the analyst assign to this alert?
⚠ Common exam trap
CS0-004 often tests the confusion between 'false positive' and 'true negative' — candidates forget that a false positive requires an alert to have actually fired on benign activity.
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
✓
False positive
A false positive is an alert that fires but does not represent a genuine security incident. Here, the 'failed login' is benign because the source is an authorized vulnerability scanner and the username does not exist — there is no real attacker or compromised account, so the SIEM rule matched on activity that is expected and non-malicious.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
False negative
Why it's wrong here
A false negative occurs when a security control fails to detect an actual, malicious threat, resulting in no alert being generated. Because the SIEM successfully triggered an alert in this scenario, it cannot be classified as a false negative, which represents a silent omission of a real attack.
- ✗
True positive
Why it's wrong here
A true positive indicates that a security system correctly identified and alerted on actual malicious activity or an unauthorized policy violation. Since the vulnerability scanner in this scenario was fully authorized and performing scheduled operations, the alert does not represent a genuine security incident or threat.
- ✗
True negative
Why it's wrong here
A true negative represents a state where no malicious activity is occurring, and the security monitoring systems correctly remain silent without generating any alerts. Because an alert was actively triggered by the SIEM, this event cannot be categorized as a true negative.
- ✓
False positive
Why this is correct
A false positive occurs when benign or authorized activity, such as an approved internal vulnerability scan, triggers a security alert as if it were malicious. Analysts must tune SIEM rules to recognize these authorized sources to prevent alert fatigue from these non-threatening events.
Go deeper
Related to this question
Learn chapter
Zero-Day Vulnerability Response
Key term
False positive
A false positive is an alert or result that indicates a security threat or vulnerability exists when in fact there is no real issue.
Key term
Vulnerability scanner
A vulnerability scanner is an automated tool that identifies security weaknesses in systems, networks, and applications by comparing their configurations and software versions against known vulnerability databases.
About these practice questions
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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 CompTIA exam blueprint
This CS0-004 practice question is part of Courseiva's free CompTIA 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 CS0-004 exam.