SCS-C02 CloudTrail Bucket Policy Practice Question
A company has a multi-account AWS organization with centralized logging in a Security account. The Security account contains an S3 bucket that stores CloudTrail logs from all member accounts. The bucket policy allows CloudTrail from member accounts to deliver logs. Recently, a security audit revealed that the bucket is publicly accessible. The security engineer must ensure that only authorized accounts can access the logs. The engineer updates the bucket policy to include a condition that restricts access to specific AWS accounts. However, after the change, member accounts report that CloudTrail is failing to deliver logs to the bucket. The bucket policy currently includes the following statement: { "Effect": "Allow", "Principal": "*", "Action": "s3:PutObject", "Resource": "arn:aws:s3:::central-logs/*", "Condition": { "StringEquals": { "aws:SourceAccount": "111111111111" } } } The Security account ID is 222222222222. What is the MOST likely cause of the delivery failure, and what should the engineer do to fix it?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the Principal from "*" to the CloudTrail service principal to restrict access more tightly.
The bucket policy's condition using `aws:SourceAccount` is not appropriate for CloudTrail. CloudTrail uses the service principal (`cloudtrail.amazonaws.com`) and the `aws:SourceAccount` key is not evaluated for service principals. The condition does not match, causing log delivery failures. Changing the Principal from `*` to the CloudTrail service principal is a necessary step to properly scope the policy. However, the condition should also be changed to use `aws:SourceArn` or removed entirely. Among the options, option C is the most direct fix, while option B is incorrect because CloudTrail does not require bucket ACLs. Options A and D are irrelevant to the issue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Modify the KMS key policy to allow CloudTrail to decrypt and re-encrypt logs if SSE-KMS is enabled.
Why it's wrong here
This is incorrect because there is no mention of SSE-KMS being enabled. Changing the KMS key policy would not resolve the condition-based failure.
- ✗
Update the bucket ACL to grant the CloudTrail service write access, as CloudTrail requires both bucket policy and ACL permissions.
Why it's wrong here
This is incorrect. CloudTrail does not require bucket ACLs; it only requires bucket policy permissions. Updating the ACL will not fix the condition issue and is unnecessary.
- ✓
Change the Principal from "*" to the CloudTrail service principal to restrict access more tightly.
Why this is correct
This is correct. Changing the Principal from `*` to the CloudTrail service principal allows the policy to match CloudTrail requests. The condition should additionally be updated to use `aws:SourceArn` for proper account restriction, but among the given options, this is the best fix.
- ✗
Create an IAM role in the Security account and configure member accounts to use that role for log delivery.
Why it's wrong here
This is incorrect. CloudTrail does not require an IAM role in the destination account for cross-account log delivery; the bucket policy is sufficient.
Visual reference
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SCS-C02 practice question is part of Courseiva's free Amazon Web Services 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 SCS-C02 exam.