S3 bucket allows delete action from all principals

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Metadata

Id: cloudformation-aws-s3-bucket-allows-delete-actions-from-all-principals

Provider: AWS

Platform: CloudFormation

Severity: Critical

Category: Access Control

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Provider Reference

Description

S3 bucket policies must not allow delete actions to all principals (*). Public delete permissions enable unauthorized users to remove or tamper with objects and buckets, causing data loss and service disruption. Check AWS::S3::BucketPolicy resources’ Properties.PolicyDocument.Statement entries. Ensure no statement has Effect: "Allow" with Principal equal to * (or an array containing *) while Action includes delete operations such as s3:DeleteObject, s3:DeleteBucket, s3:DeleteObjectVersion, or wildcard actions that grant delete privileges.

Statements that combine Effect: "Allow", Principal: "*", and any delete action will be flagged. Instead, restrict delete permissions to explicit principals (account IDs, ARNs, or specific service principals) or remove Allow for delete actions to public principals. Action may be a single string or a list. Both forms are checked.

Secure example restricting delete to a specific AWS account:

MyBucketPolicy:
  Type: AWS::S3::BucketPolicy
  Properties:
    Bucket: my-bucket
    PolicyDocument:
      Statement:
        - Sid: AllowSpecificAccountDeletes
          Effect: Allow
          Principal:
            AWS: "arn:aws:iam::123456789012:root"
          Action:
            - "s3:DeleteObject"
            - "s3:DeleteObjectVersion"
          Resource: "arn:aws:s3:::my-bucket/*"

Compliant Code Examples

#this code is a correct code for which the query should not find any result
Resources:
  SampleBucketPolicy1:
    Type: 'AWS::S3::BucketPolicy'
    Properties:
      Bucket: !Ref DOC-EXAMPLE-BUCKET
      PolicyDocument:
        Statement:
          - Action:
              - 's3:DeleteObject'
            Effect: Deny
            Resource: '*'
            Principal: '*'
            Condition:
              StringLike:
                'aws:Referer':
                  - 'http://www.example.com/*'
                  - 'http://example.net/*'

Non-Compliant Code Examples

#this is a problematic code where the query should report a result(s)
Resources:
  SampleBucketPolicy3:
    Type: 'AWS::S3::BucketPolicy'
    Properties:
      Bucket: !Ref DOC-EXAMPLE-BUCKET
      PolicyDocument:
        Statement:
          - Action: "DeleteObject"
            Effect: Allow
            Resource: "*"
            Principal: "*"
            Condition:
              StringLike:
                'aws:Referer':
                  - 'http://www.example.com/*'
                  - 'http://example.net/*'
  SampleBucketPolicy4:
    Type: 'AWS::S3::BucketPolicy'
    Properties:
      Bucket: !Ref DOC-EXAMPLE-BUCKET
      PolicyDocument:
        Statement:
          - Action:
              - "DeleteObject"
              - "GetObject"
            Effect: Allow
            Resource: "*"
            Principal: "*"
            Condition:
              StringLike:
                'aws:Referer':
                  - 'http://www.example.com/*'
                  - 'http://example.net/*'