ANS-C01 Network Security, Compliance and Governance Practice Question

Exhibit

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Deny",
      "Action": "s3:PutObject",
      "Resource": "arn:aws:s3:::important-bucket/*",
      "Condition": {
        "StringNotEquals": {
          "s3:x-amz-server-side-encryption": "aws:kms"
        }
      }
    }
  ]
}

Refer to the exhibit. A company has an S3 bucket policy that denies PutObject if the object is not encrypted with SSE-KMS. However, uploads are still being allowed without encryption. What is the most likely reason?

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 condition key 's3:x-amz-server-side-encryption' is not present in the upload request, so the condition is not evaluated and the Deny is not applied.

The bucket policy uses a condition key 's3:x-amz-server-side-encryption' to deny uploads that are not encrypted with SSE-KMS. However, if the upload request does not include the 'x-amz-server-side-encryption' header at all, the condition key is not present in the request, so the condition is not evaluated. As a result, the Deny effect is not applied, and the upload is allowed. Option A is incorrect because the policy is valid JSON and would be enforced if the condition were met. Option B is incorrect because an explicit Allow in an IAM policy cannot override a Deny in a bucket policy; the Deny would still apply. Option D is incorrect because bucket policies are evaluated regardless of region as long as the bucket is in the same region as the request's endpoint; the region is not the issue here.

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 bucket policy has a syntax error and is not being enforced.
Why it's wrong here
The policy syntax is correct.
✗
The IAM user has an explicit Allow that overrides the Deny in the bucket policy.
Why it's wrong here
An explicit Deny in a bucket policy overrides any Allow from IAM.
✓
The condition key 's3:x-amz-server-side-encryption' is not present in the upload request, so the condition is not evaluated and the Deny is not applied.
Why this is correct
If the header is omitted, the condition evaluates to false, and the Deny statement is not triggered.
✗
The bucket policy must be attached to the bucket in the same region as the request.
Why it's wrong here
Bucket policies are region-specific but that is not the issue here.

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

ANS-C01 Network Security, Compliance and Governance Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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