The correct answer is to create an IAM role with an S3 read policy and attach it to the Lambda function as its execution role. This works because Lambda functions assume this IAM execution role to obtain temporary credentials from AWS Security Token Service (STS), and the attached policy granting s3:GetObject permissions authorizes the function to read objects from the S3 bucket without embedding long-term access keys. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of least privilege and the principle that Lambda never inherits permissions from the caller—it always relies on its own execution role. A common trap is assuming you can attach a policy directly to the Lambda function or use the caller’s IAM role; instead, remember that the execution role is the sole mechanism for granting AWS resource access. Memory tip: “Lambda lives by its own role—never borrows from the caller’s soul.”
SCS-C02 Identity and Access Management Practice Question
This SCS-C02 practice question tests your understanding of identity and access management. 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 company wants to allow a Lambda function to read objects from an S3 bucket in the same account. What should be done?
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 Lambda function.
Option B is correct because Lambda functions require an IAM role (execution role) to obtain temporary AWS credentials via the AWS Security Token Service (STS). Attaching a policy with s3:GetObject permissions to this role grants the Lambda function the necessary access to read objects from the S3 bucket without hardcoding long-term credentials.
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 IAM user access keys in the Lambda function's environment variables.
Why it's wrong here
This is not a recommended practice; IAM roles are preferred for Lambda.
✓
Create an IAM role with an S3 read policy and attach it to the Lambda function.
Why this is correct
Lambda assumes the role to get temporary credentials.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add a bucket policy allowing s3:GetObject for the Lambda service principal.
Why it's wrong here
Lambda runs as a role, not as the service principal itself.
✗
Configure the S3 bucket to be public.
Why it's wrong here
This would expose the bucket publicly, which is insecure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the Lambda service principal (lambda.amazonaws.com) with the Lambda execution role, incorrectly assuming that a bucket policy can grant access directly to the Lambda service rather than to the IAM role that the Lambda function assumes.
Detailed technical explanation
How to think about this question
Under the hood, the Lambda execution role's trust policy allows the lambda.amazonaws.com service to assume the role, and the attached IAM policy defines the S3 actions. The Lambda runtime automatically retrieves temporary credentials from the instance metadata service (IMDS) or the ECS credential provider, which are valid for up to 6 hours and are rotated automatically. In a cross-account scenario, you would combine an IAM role in the Lambda account with a bucket policy granting access to that role's ARN, but within the same account, the execution role alone is sufficient.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Identity and Access Management — This question tests Identity and Access Management — 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 Lambda function. — Option B is correct because Lambda functions require an IAM role (execution role) to obtain temporary AWS credentials via the AWS Security Token Service (STS). Attaching a policy with s3:GetObject permissions to this role grants the Lambda function the necessary access to read objects from the S3 bucket without hardcoding long-term credentials.
What should I do if I get this SCS-C02 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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