This CCSP practice question tests your understanding of cloud application security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 developer is writing code that will be deployed as a serverless function (e.g., AWS Lambda). The function needs to read data from an Amazon S3 bucket. According to the principle of least privilege, how should the developer grant access?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "least"
Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create an IAM role with an S3 read policy and attach it to the function
Option D is correct because AWS Lambda functions should assume an IAM role that grants only the specific permissions needed—in this case, an S3 read policy. This follows the principle of least privilege by avoiding hardcoded credentials and instead using temporary, automatically rotated credentials provided by the AWS Security Token Service (STS) via the IAM role. The role is attached to the Lambda function at deployment, ensuring the function can securely access the S3 bucket without exposing long-term access keys.
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.
✗
Store the AWS access key and secret key in environment variables in the function
Why it's wrong here
Hardcoding credentials is insecure and not scalable.
✗
Use the root user credentials of the AWS account
Why it's wrong here
Root user has unrestricted access and should not be used for day-to-day tasks.
✗
Set the S3 bucket policy to allow public read access
Why it's wrong here
Public access exposes the data to anyone on the internet.
✓
Create an IAM role with an S3 read policy and attach it to the function
Why this is correct
This grants only the necessary permissions and follows least privilege.
Clue confirmation
The clue word "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the misconception that environment variables are a secure way to store credentials in serverless functions, but the trap is that AWS Lambda’s native IAM role integration provides temporary, automatically rotated credentials that are far more secure and align with least privilege, whereas static keys in environment variables introduce long-term exposure risks.
Detailed technical explanation
How to think about this question
When a Lambda function assumes an IAM role, the AWS Lambda service calls the STS AssumeRole API to obtain temporary security credentials (access key, secret key, and session token) that are automatically injected into the function's runtime environment via environment variables (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN). These credentials are valid for up to 6 hours and are rotated automatically on each invocation, eliminating the need for manual credential management. In a real-world scenario, if the function needs to read from multiple S3 buckets, you would scope the IAM policy to specific bucket ARNs and actions (e.g., s3:GetObject on arn:aws:s3:::example-bucket/*) to further enforce least privilege.
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.
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.
Cloud Application Security — This question tests Cloud Application Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create an IAM role with an S3 read policy and attach it to the function — Option D is correct because AWS Lambda functions should assume an IAM role that grants only the specific permissions needed—in this case, an S3 read policy. This follows the principle of least privilege by avoiding hardcoded credentials and instead using temporary, automatically rotated credentials provided by the AWS Security Token Service (STS) via the IAM role. The role is attached to the Lambda function at deployment, ensuring the function can securely access the S3 bucket without exposing long-term access keys.
What should I do if I get this CCSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "least". You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
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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