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.
A penetration tester discovers a web application that deserializes user-controlled data without validation. The application uses Java serialization. The tester creates a malicious serialized object that executes a system command. Which of the following conditions is required for this exploit to succeed?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Java runtime must have a gadget chain available in its classpath
Java deserialization exploits rely on the presence of specific classes (gadget chains) in the application's classpath that can be chained together to achieve arbitrary code execution. The attacker crafts a serialized object that, when deserialized, triggers a sequence of method calls (gadget chain) that ultimately executes a system command. Without a suitable gadget chain available in the classpath, the deserialization of a malicious object will not lead to code execution.
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.
✗
The application must be running with root privileges
Why it's wrong here
Code execution through deserialization can happen with the application's user privileges; root is not required.
✗
The application must use a custom ClassLoader
Why it's wrong here
A custom ClassLoader is not necessary; the attack uses existing classes in the default class path.
✓
The Java runtime must have a gadget chain available in its classpath
Why this is correct
Gadget chains like those in Apache Commons Collections are necessary to transform deserialization into code execution.
Related concept
Read the scenario before looking for a memorised answer.
✗
The application must be running on a Windows operating system
Why it's wrong here
Java deserialization vulnerabilities are platform-independent; the OS does not affect the availability of gadget chains.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that privilege escalation (root) or custom class loading is required, when in fact the core requirement is the availability of gadget chains in the classpath.
Detailed technical explanation
How to think about this question
Common gadget chains in Java deserialization exploits include libraries like Apache Commons Collections, Spring, or JDK built-in classes (e.g., Runtime.exec via ChainedTransformer). The ysoserial tool automates the generation of payloads for known gadget chains, and the exploit's success depends entirely on the specific libraries and versions present in the target application's classpath. A real-world scenario is the 2015 Apache Commons Collections vulnerability (CVE-2015-7501) used in attacks against JBoss and WebLogic servers.
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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
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: The Java runtime must have a gadget chain available in its classpath — Java deserialization exploits rely on the presence of specific classes (gadget chains) in the application's classpath that can be chained together to achieve arbitrary code execution. The attacker crafts a serialized object that, when deserialized, triggers a sequence of method calls (gadget chain) that ultimately executes a system command. Without a suitable gadget chain available in the classpath, the deserialization of a malicious object will not lead to code execution.
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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