Quick Answer
The answer is Cross-Site Scripting (XSS), specifically reflected XSS, because the application accepts user input and renders it directly in the browser without sanitization, allowing an attacker to inject malicious JavaScript that executes in the victim's session. This vulnerability arises when the server fails to validate or encode output, enabling the attacker to craft a URL containing the payload that, when clicked, reflects the script back to the user’s browser. On the Certified Ethical Hacker CEH exam, this scenario tests your ability to distinguish XSS from server-side attacks like SQL injection or command injection, which target databases or the operating system rather than the client-side DOM. A common trap is confusing reflected XSS with stored XSS—remember that reflected XSS is non-persistent and requires the victim to click a crafted link, while stored XSS saves the payload on the server. For a quick memory tip, think “Reflect and Redirect”: if the input echoes back immediately in the response, it’s reflected XSS.
This CEH practice question tests your understanding of network and web application attacks. 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.
During a penetration test, you notice that a web application accepts user input and displays it directly in the browser without sanitization. Which attack is most likely to succeed?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
SQL Injection
Why wrong: SQL injection targets database queries, not browser output.
Cross-Site Request Forgery (CSRF)
Why wrong: CSRF exploits user authentication to perform unauthorized actions.
Cross-Site Scripting (XSS)
Reflected XSS is the direct result of unsanitized input displayed in the browser.
Command Injection
Why wrong: Command injection targets server-side command execution.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Cross-Site Scripting (XSS)
Option C is correct because the scenario describes a classic reflected Cross-Site Scripting (XSS) vulnerability. The application accepts user input and displays it directly in the browser without sanitization, allowing an attacker to inject malicious JavaScript that executes in the victim's browser. This is the defining characteristic of XSS, not SQL injection or command injection, which target server-side interpreters.
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.
SQL Injection
Why it's wrong here
SQL injection targets database queries, not browser output.
Cross-Site Request Forgery (CSRF)
Why it's wrong here
CSRF exploits user authentication to perform unauthorized actions.
Cross-Site Scripting (XSS)
Why this is correct
Reflected XSS is the direct result of unsanitized input displayed in the browser.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Command Injection
Why it's wrong here
Command injection targets server-side command execution.
Common exam traps
EC-Council often tests the distinction between reflected XSS and stored XSS; the trap here is that candidates may assume any unsanitized input is SQL injection, but the key clue is direct display in the browser without server-side processing like database queries or command execution.
Trap categories for this question
Command / output trap
SQL injection targets database queries, not browser output.
Detailed technical explanation
In reflected XSS, the unsanitized input is typically echoed back in the HTTP response body, often within a script context or HTML attribute. For example, if the input is placed inside a <script> tag without encoding, an attacker can inject a payload like <script>alert('XSS')</script>. Real-world attacks often use event handlers (e.g., onerror) or break out of existing HTML attributes to execute arbitrary JavaScript, bypassing simple filters.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network and Web Application Attacks — study guide chapter
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FAQ
Network and Web Application Attacks — This question tests Network and Web Application Attacks — Read the scenario before looking for a memorised answer..
The correct answer is: Cross-Site Scripting (XSS) — Option C is correct because the scenario describes a classic reflected Cross-Site Scripting (XSS) vulnerability. The application accepts user input and displays it directly in the browser without sanitization, allowing an attacker to inject malicious JavaScript that executes in the victim's browser. This is the defining characteristic of XSS, not SQL injection or command injection, which target server-side interpreters.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Refer to the exhibit. A security analyst captured the HTTP request and response shown. What type of vulnerability is present?
mediumWhy C: The HTTP response contains the search query parameter directly reflected in the HTML body without proper sanitization or encoding. Specifically, the request includes `?search=<script>alert('XSS')</script>` and the response echoes this payload verbatim in the page content, allowing the browser to execute the injected JavaScript. This is the classic signature of a reflected cross-site scripting (XSS) vulnerability, where the malicious script is immediately reflected off the web server and executed in the user's browser.
Last reviewed: Jun 30, 2026
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