The answer is using bounded string functions like strncpy instead of strcpy. This is correct because bounded functions enforce explicit length limits on data copied into a buffer, preventing writes beyond the allocated memory boundary—the root cause of a buffer overflow. By performing bounds checking before any memory operation, these functions ensure that array indices and pointers never reference adjacent memory, which an attacker could otherwise overwrite to inject malicious code or alter execution flow. On the CISSP exam, this concept appears in the Software Development Security domain, often testing your ability to distinguish between secure and legacy functions; a common trap is assuming that any string function is safe, when in fact unbounded functions like gets or sprintf are still frequently seen in multiple-choice distractors. Remember the mnemonic “Bound to be safe”—if a function name includes “n” for number (e.g., strncpy, snprintf), it is performing explicit length control, directly preventing overflow.
CISSP Software Development Security Practice Question
This CISSP practice question tests your understanding of software development security. 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 secure coding practices to prevent buffer overflow vulnerabilities? (Select TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Perform bounds checking on array indices and pointers
Bounds checking ensures that array indices and pointers do not reference memory outside the allocated buffer, directly preventing the overwrite of adjacent memory that leads to buffer overflows. This is a fundamental defensive coding practice that validates all input and index values before use.
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.
✓
Perform bounds checking on array indices and pointers
Why this is correct
Bounds checking ensures memory accesses are within allocated space.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use dynamic memory allocation for all buffers
Why it's wrong here
Dynamic allocation does not prevent overflows if bounds are not checked.
✗
Enable Address Space Layout Randomization (ASLR)
Why it's wrong here
ASLR is an OS-level mitigation, not a coding practice.
✓
Use bounded string functions (e.g., strncpy instead of strcpy)
Why this is correct
Bounded functions limit the number of characters copied, preventing overflow.
Related concept
Read the scenario before looking for a memorised answer.
✗
Deallocate memory after use
Why it's wrong here
Deallocation prevents memory leaks, not buffer overflows.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse system-level mitigations (like ASLR) or memory management practices (like deallocation) with actual secure coding practices that prevent the vulnerability from being written into the code.
Detailed technical explanation
How to think about this question
Buffer overflows exploit the lack of bounds checking on stack or heap buffers, allowing an attacker to overwrite the return address or function pointers. Bounded string functions like strncpy limit the number of bytes copied to the destination buffer size minus one for the null terminator, but even they can be misused if the size parameter is incorrect (e.g., off-by-one errors). In real-world scenarios, such as the 2014 Heartbleed vulnerability in OpenSSL, a missing bounds check on a memcpy call allowed reading beyond the buffer, leaking sensitive 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 security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Software Development Security — This question tests Software Development Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Perform bounds checking on array indices and pointers — Bounds checking ensures that array indices and pointers do not reference memory outside the allocated buffer, directly preventing the overwrite of adjacent memory that leads to buffer overflows. This is a fundamental defensive coding practice that validates all input and index values before use.
What should I do if I get this CISSP 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.
About these practice questions
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Variation 1. Which TWO of the following are secure coding practices to prevent buffer overflow vulnerabilities?
easy
A.Code obfuscation.
✓ B.Input validation.
C.Dynamic memory allocation without bounds.
D.Use of unsafe functions like strcpy.
✓ E.Use of compilers with stack protection.
Why B: Input validation ensures data fits within buffers; stack protection (e.g., canaries) detects overflow. Unsafe functions like strcpy are a cause, not prevention. Dynamic memory allocation without bounds still risks overflow. Code obfuscation does not prevent overflow.
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This CISSP practice question is part of Courseiva's free ISC2 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 CISSP exam.
Question Discussion
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