SCS-C02 Threat Detection and Incident Response Practice Question
During a security review, a security engineer notices that an S3 bucket contains sensitive data but has a bucket policy that allows access from any principal in the account. The engineer needs to identify any unintended cross-account access to this bucket. Which AWS service should be used?
⚠ Common exam trap
A common mix-up: candidates confuse AWS Config (which can detect public S3 buckets) with IAM Access Analyzer (which specifically detects cross-account access), leading them to choose Config when the question explicitly asks for unintended cross-account access, not just public 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
✓
AWS IAM Access Analyzer
AWS IAM Access Analyzer helps identify resources that are shared with external principals by analyzing resource-based policies (like S3 bucket policies). In this scenario, the bucket policy allows access from any principal in the account, but IAM Access Analyzer can detect if the policy also grants access to principals outside the AWS account (cross-account access). It generates findings for any policy that allows access from an external entity, making it the correct service to identify unintended cross-account access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS Config
Why it's wrong here
AWS Config tracks resource configuration changes and evaluates compliance against rules, but its purpose is not to analyze IAM resource policies for cross-account access. You could write a custom Config rule to inspect a policy document, but that requires custom logic and doesn't provide the automated, comprehensive external-entity analysis that IAM Access Analyzer performs. Config is a compliance and change-management tool, not a policy-analysis tool.
- ✓
AWS IAM Access Analyzer
Why this is correct
AWS IAM Access Analyzer is specifically designed to identify unintended access to your resources from external entities. It applies automated reasoning to resource-based policies and generates findings that list the external principal, the resource, and the specific action granted, helping security engineers quickly identify and remediate cross-account access. This makes it the correct service for a security review focused on discovering whether any external accounts have been granted access to your resources.
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AWS Trusted Advisor
Why it's wrong here
AWS Trusted Advisor offers checks for cloud security best practices, such as IAM root access, MFA on root account, open security groups, and public S3 buckets, but it does not analyze individual policy documents for complex cross-account grants. It might tell you a bucket is publicly accessible, but it won't identify that a specific IAM role policy grants read/write to a specific external account ID. Trusted Advisor lacks the granular policy-level analysis that IAM Access Analyzer provides, so it cannot satisfy this review requirement.
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Amazon Macie
Why it's wrong here
Amazon Macie is a data visibility and security service that discovers sensitive data (PII, credentials, etc.) in S3 buckets using machine learning and pattern matching. It doesn't evaluate IAM policies or resource policies to determine whether external principals have access; it inspects the data content itself. Therefore, while Macie could alert you to the presence of sensitive data in a bucket, it wouldn't tell you that a bucket policy grants DeleteObject to an external account.
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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About these practice questions
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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.