Quick Answer
The correct answer is XML External Entity (XXE) injection. This payload exploits a misconfigured XML parser by defining an external entity, `&xxe;`, that references the system file `file:///etc/passwd`, causing the server to read and return the contents of that sensitive local file. On the Certified Ethical Hacker CEH exam, this question tests your ability to recognize how attackers abuse XML entity expansion to achieve file disclosure, server-side request forgery, or denial of service. A common trap is confusing XXE with simple XML injection or XPath injection, but the key differentiator is the use of the `SYSTEM` keyword to load external resources. Remember the memory tip: “SYSTEM means source outside the document” — if you see `SYSTEM` in a DOCTYPE declaration, think XXE.
This CEH practice question tests your understanding of web application and injection 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.
A web application uses XML to transfer data. An attacker submits the following payload: '<!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///etc/passwd">]><root>&xxe;</root>'. What vulnerability is being exploited?
XML External Entity (XXE) injection
The DOCTYPE declaration with an external entity reading a file is classic XXE.
Directory traversal
Why wrong: Directory traversal uses '../' in file paths, not XML entities.
Server-Side Request Forgery (SSRF)
Why wrong: SSRF involves HTTP requests from the server, not XML entities.
Command injection
Why wrong: Command injection would involve executing shell commands, not XML entities.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
XML External Entity (XXE) injection
This is an XML External Entity (XXE) injection attack, where an external entity is defined to read local files.
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.
XML External Entity (XXE) injection
Why this is correct
The DOCTYPE declaration with an external entity reading a file is classic XXE.
Related concept
Read the scenario before looking for a memorised answer.
Directory traversal
Why it's wrong here
Directory traversal uses '../' in file paths, not XML entities.
Server-Side Request Forgery (SSRF)
Why it's wrong here
SSRF involves HTTP requests from the server, not XML entities.
Command injection
Why it's wrong here
Command injection would involve executing shell commands, not XML entities.
Common exam traps
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
Command injection would involve executing shell commands, not XML entities.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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 CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Web Application and Injection Attacks — This question tests Web Application and Injection Attacks — Read the scenario before looking for a memorised answer..
The correct answer is: XML External Entity (XXE) injection — This is an XML External Entity (XXE) injection attack, where an external entity is defined to read local files.
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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. A web application uses an XML parser to process user-supplied XML documents. An attacker submits the following payload: <?xml version='1.0'?><!DOCTYPE foo [<!ENTITY xxe SYSTEM 'file:///etc/passwd'>]><root>&xxe;</root>. Which vulnerability is being exploited?
hardWhy C: The payload defines an external entity that reads a local file, which is classic XXE (XML External Entity) injection.
Last reviewed: Jun 21, 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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