SNS Topic is Publicly Accessible

• Query id: ae53ce91-42b5-46bf-a84f-9a13366a4f13
• Query name: SNS Topic is Publicly Accessible
• Platform: CloudFormation
• Severity: Critical
• Category: Access Control
• URL: Github

Description

SNS Topic Policy should not allow any principal to access
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - yaml file

AWSTemplateFormatVersion: '2010-09-09'
Description: ''
Resources:
  snsPolicy:
      Type: AWS::SNS::TopicPolicy
      Properties:
        PolicyDocument:
          Statement: [
            {
              "Sid": "MyTopicPolicy",
              "Effect": "Allow",
              "Principal": "*",
              "Action": ["sns:Publish"],
              "Resource": "arn:aws:sns:MyTopic"
            }]

Positive test num. 2 - json file

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "",
  "Resources": {
    "mysnspolicy0" : {
      "Type" : "AWS::SNS::TopicPolicy",
      "Properties" : {
        "PolicyDocument" :  {
          "Id" : "MyTopicPolicy",
          "Version" : "2012-10-17",
          "Statement" : [ {
            "Sid" : "My-statement-id",
            "Effect" : "Allow",
            "Principal" : "*",
            "Action" : "sns:Publish",
            "Resource" : "*"
          } ]
        },
        "Topics" : [ { "Ref" : "MySNSTopic" } ]
      }
    }
  }
}

Code samples without security vulnerabilities

Negative test num. 1 - yaml file

AWSTemplateFormatVersion: '2010-09-09'
Description: ''
Resources:
  snsPolicy:
      Type: AWS::SNS::TopicPolicy
      Properties:
        PolicyDocument:
          Statement: [
            {
              "Sid": "MyTopicPolicy",
              "Effect": "Allow",
              "Principal": "otherPrincipal",
              "Action": ["sns:Publish"],
              "Resource": "arn:aws:sns:MyTopic"
            }]

Negative test num. 2 - json file

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "",
  "Resources": {
    "mysnspolicy0" : {
      "Type" : "AWS::SNS::TopicPolicy",
      "Properties" : {
        "PolicyDocument" :  {
          "Id" : "MyTopicPolicy",
          "Version" : "2012-10-17",
          "Statement" : [ {
            "Sid" : "My-statement-id",
            "Effect" : "Allow",
            "Principal" : "otherPrincipal",
            "Action" : "sns:Publish",
            "Resource" : "*"
          } ]
        },
        "Topics" : [ { "Ref" : "MySNSTopic" } ]
      }
    }
  }
}