The answer is using the transient keyword for sensitive fields, overriding resolveClass() in ObjectInputStream, and applying ObjectInputFilter. The transient keyword prevents sensitive data from being serialized, eliminating exposure during transmission or storage. Overriding resolveClass() lets you validate and whitelist allowed class names before deserialization, blocking malicious classes that could execute arbitrary code. ObjectInputFilter provides a configurable, global filter to reject untrusted classes or data sizes. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this question tests your understanding of deserialization attack vectors and the three layered defenses: field-level protection (transient), class-level validation (resolveClass), and stream-level filtering (ObjectInputFilter). A common trap is assuming serialVersionUID alone provides security—it does not. Remember the mnemonic “TRIP”: Transient, ResolveClass, InputFilter—three pillars to secure serialization.
1Z0-829 Java I/O API and Securing Applications Practice Question
This 1Z0-829 practice question tests your understanding of java i/o api and securing applications. 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 three actions help secure a Java application that uses serialization? (Select three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Overriding resolveClass() in ObjectInputStream to validate class names.
Option A is correct because overriding `resolveClass()` in `ObjectInputStream` allows you to validate the class name before it is deserialized. This prevents deserialization attacks where an attacker sends a malicious class that could execute arbitrary code. By checking the class name against a whitelist, you can block untrusted classes from being loaded.
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.
✓
Overriding resolveClass() in ObjectInputStream to validate class names.
Why this is correct
Allows filtering of classes during deserialization.
Related concept
Read the scenario before looking for a memorised answer.
✓
Implementing ObjectInputFilter to set a deserialization filter.
Why this is correct
Standard way to restrict deserialization in Java 9+.
Related concept
Read the scenario before looking for a memorised answer.
✓
Using transient keyword for sensitive fields.
Why this is correct
Prevents sensitive data from being serialized.
Related concept
Read the scenario before looking for a memorised answer.
✗
Using SecureRandom to generate serialVersionUID.
Why it's wrong here
serialVersionUID is a long constant, not generated with SecureRandom.
✗
Declaring serialVersionUID explicitly as a long constant.
Why it's wrong here
Helps with version compatibility but does not prevent attacks.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse versioning best practices (like declaring `serialVersionUID`) with security controls, or think that using `SecureRandom` for `serialVersionUID` adds security, when in fact it only breaks compatibility and does nothing to prevent deserialization attacks.
Detailed technical explanation
How to think about this question
Under the hood, `ObjectInputFilter` (option B) works by setting a filter on the `ObjectInputStream` that can reject classes based on patterns, limits, or custom logic, effectively blocking deserialization of malicious objects. The `transient` keyword (option C) prevents a field from being serialized, which is critical for sensitive data like passwords or encryption keys, as serialized objects can be intercepted or inspected. In real-world attacks like the Apache Commons Collections vulnerability, attackers exploit the default deserialization mechanism to execute arbitrary code; combining class validation, filters, and marking sensitive fields as transient forms a defense-in-depth strategy.
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 practitioner preparing for the 1Z0-829 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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Java I/O API and Securing Applications — This question tests Java I/O API and Securing Applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Overriding resolveClass() in ObjectInputStream to validate class names. — Option A is correct because overriding `resolveClass()` in `ObjectInputStream` allows you to validate the class name before it is deserialized. This prevents deserialization attacks where an attacker sends a malicious class that could execute arbitrary code. By checking the class name against a whitelist, you can block untrusted classes from being loaded.
What should I do if I get this 1Z0-829 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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Variation 1. An application deserializes objects from a network stream. To protect against deserialization attacks, which approach is most effective in Java 17?
hard
A.Declare all fields as transient
✓ B.Set an ObjectInputFilter on the ObjectInputStream
C.Use try-with-resources to auto-close the stream
D.Mark the class as final
Why B: Option B is correct because setting an ObjectInputFilter on the ObjectInputStream allows you to define a filter that can reject deserialization of arbitrary or malicious classes, which is the primary defense against deserialization attacks. This mechanism, introduced in Java 9 and enhanced in later versions, lets you whitelist or blacklist classes based on patterns, limits on array sizes, or depth of object graphs, directly mitigating the risk of remote code execution or denial-of-service via crafted serialized data.
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Question Discussion
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