ANS-C01 Network Security, Compliance and Governance Practice Question
A security engineer is designing a network security architecture for a multi-account AWS environment using AWS Organizations. The company requires that all VPC flow logs be delivered to a central S3 bucket in the security account. The security engineer has created a bucket policy that grants the necessary permissions. However, flow logs from member accounts are failing to be delivered. What is the most likely cause?
⚠ Common exam trap
AWS often tests the confused deputy problem in cross-account service delivery scenarios, and the trap here is that candidates mistakenly focus on IAM roles or root user permissions instead of recognizing that the bucket policy must include a source condition to prevent unauthorized access.
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
✓
The bucket policy does not include a condition that restricts access to the flow log delivery service using aws:SourceArn or aws:SourceAccount.
The VPC Flow Logs delivery service uses a service-linked role to write to the destination S3 bucket. Without a condition in the bucket policy that restricts access using `aws:SourceArn` or `aws:SourceAccount`, the policy is vulnerable to the confused deputy problem, where a different AWS service or account could potentially write to the bucket. The missing condition causes the delivery to fail because the service cannot verify that the request originated from the expected source.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The member accounts have not created an IAM role with permissions to write to the central bucket.
Why it's wrong here
VPC Flow Logs use a service-linked role, not an IAM role in member accounts.
- ✓
The bucket policy does not include a condition that restricts access to the flow log delivery service using aws:SourceArn or aws:SourceAccount.
Why this is correct
This condition is essential to prevent the confused deputy problem.
- ✗
The bucket policy does not grant write access to the member accounts' root user.
Why it's wrong here
The bucket policy should grant access to the VPC Flow Logs service principal, not the member account root.
- ✗
The central S3 bucket has not been configured with ACLs enabled.
Why it's wrong here
ACLs are not required; bucket policy is used.
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 |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 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 ANS-C01 exam.