Quick Answer
The correct answer is the WPS PIN brute-force weakness, as Reaver is a tool specifically designed to exploit this vulnerability in Wi-Fi Protected Setup. The attack works because the WPS PIN is split into two halves—the first half has only 4 digits (10,000 possibilities) and the second half has 3 digits with a checksum (just 1,000 possibilities)—and the WPS registrar lacks rate-limiting, allowing Reaver to brute-force each half separately and recover the full PIN, which then reveals the WPA2 pre-shared key. On the Certified Ethical Hacker CEH exam, this question tests your understanding of wireless attack vectors and tools; a common trap is confusing Reaver with tools like Aircrack-ng (which targets WEP or WPA handshakes) or thinking it exploits a protocol flaw in WPA2 itself. Remember the memory tip: “Reaver splits the PIN—first four, then three, and the checksum is the key.”
This CEH practice question tests your understanding of advanced topics: wireless, cloud, iot, cryptography. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A penetration tester uses the tool Reaver to target a Wi-Fi network. What vulnerability is the tester attempting to exploit?
WPA2 4-way handshake capture
Why wrong: Handshake capture is done with airodump-ng, not Reaver.
WPS PIN brute-force weakness
Reaver performs a brute-force attack on the WPS PIN (typically 8 digits) to recover PSK.
Weak WEP encryption keys
Why wrong: WEP keys are cracked with aircrack-ng, not Reaver.
RADIUS authentication bypass
Why wrong: RADIUS bypass requires exploiting authentication servers, not a WPS attack.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
WPS PIN brute-force weakness
Reaver is a tool specifically designed to exploit the WPS (Wi-Fi Protected Setup) PIN brute-force vulnerability. It targets the WPS registrar's lack of rate-limiting and the fact that the PIN is split into two halves (first half 4 digits, second half 3 digits with a checksum), allowing an attacker to recover the WPS PIN and subsequently the WPA2 pre-shared key in a matter of hours.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
WPA2 4-way handshake capture
Why it's wrong here
Handshake capture is done with airodump-ng, not Reaver.
WPS PIN brute-force weakness
Why this is correct
Reaver performs a brute-force attack on the WPS PIN (typically 8 digits) to recover PSK.
Related concept
Read the scenario before looking for a memorised answer.
Weak WEP encryption keys
Why it's wrong here
WEP keys are cracked with aircrack-ng, not Reaver.
RADIUS authentication bypass
Why it's wrong here
RADIUS bypass requires exploiting authentication servers, not a WPS attack.
Common exam traps
EC-Council often tests the distinction between WPS PIN brute-force (Reaver) and WPA2 handshake capture (aircrack-ng), so candidates mistakenly associate any wireless attack with handshake capture rather than recognizing the specific tool-to-vulnerability mapping.
Detailed technical explanation
The WPS PIN consists of 8 digits, but the last digit is a checksum, reducing the effective keyspace. The first 4 digits are verified separately from the last 3 digits, meaning an attacker only needs to brute-force 10^4 + 10^3 = 11,000 attempts at most. Reaver sends EAPOL start messages to the access point's WPS registrar and uses the WPS protocol's M1–M8 message exchange to test PIN guesses, exploiting the lack of lockout mechanisms in many consumer routers.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
What to study next
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FAQ
Advanced Topics: Wireless, Cloud, IoT, Cryptography — This question tests Advanced Topics: Wireless, Cloud, IoT, Cryptography — Read the scenario before looking for a memorised answer..
The correct answer is: WPS PIN brute-force weakness — Reaver is a tool specifically designed to exploit the WPS (Wi-Fi Protected Setup) PIN brute-force vulnerability. It targets the WPS registrar's lack of rate-limiting and the fact that the PIN is split into two halves (first half 4 digits, second half 3 digits with a checksum), allowing an attacker to recover the WPS PIN and subsequently the WPA2 pre-shared key in a matter of hours.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This CEH 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 CEH exam.
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