RDS DB Instance Publicly Accessible

• Query id: de38e1d5-54cb-4111-a868-6f7722695007
• Query name: RDS DB Instance Publicly Accessible
• Platform: CloudFormation
• Severity: Critical
• Category: Insecure Configurations
• CWE: 668
• URL: Github

Description

RDS must not be defined with public interface, which means the attribute 'PubliclyAccessible' must be set to false.
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - yaml file

#this is a problematic code where the query should report a result(s)
AWSTemplateFormatVersion: 2010-09-09
Description: >-
  Description": "AWS CloudFormation Sample Template for creating an Amazon RDS DB instance:
  Sample template showing how to create a DB instance with Enhanced Monitoring enabled.
  **WARNING** This template creates an RDS DB instance. You will be billed for the AWS
  resources used if you create a stack from this template.
Parameters:
  DBInstanceID:
    Default: mydbinstance
    Description: My database instance
    Type: String
    MinLength: '1'
    MaxLength: '63'
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    ConstraintDescription: >-
      Must begin with a letter and must not end with a hyphen or contain two
      consecutive hyphens.
  DBName:
    Default: mydb
    Description: My database
    Type: String
    MinLength: '1'
    MaxLength: '64'
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    ConstraintDescription: Must begin with a letter and contain only alphanumeric characters.
  DBInstanceClass:
    Default: db.m5.large
    Description: DB instance class
    Type: String
    ConstraintDescription: Must select a valid DB instance type.
  DBAllocatedStorage:
    Default: '50'
    Description: The size of the database (GiB)
    Type: Number
    MinValue: '5'
    MaxValue: '1024'
    ConstraintDescription: must be between 20 and 65536 GiB.
  DBUsername:
    NoEcho: 'true'
    Description: Username for MySQL database access
    Type: String
    MinLength: '1'
    MaxLength: '16'
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    ConstraintDescription: must begin with a letter and contain only alphanumeric characters.
  DBPassword:
    NoEcho: 'true'
    Description: Password MySQL database access
    Type: String
    MinLength: '8'
    MaxLength: '41'
    AllowedPattern: '[a-zA-Z0-9]*'
    ConstraintDescription: must contain only alphanumeric characters.
Resources:
  MyDB:
    Type: 'AWS::RDS::DBInstance'
    Properties:
      DBInstanceIdentifier: !Ref DBInstanceID
      DBName: !Ref DBName
      DBInstanceClass: !Ref DBInstanceClass
      AllocatedStorage: !Ref DBAllocatedStorage
      Engine: MySQL
      EngineVersion: 8.0.16
      MasterUsername: !Ref DBUsername
      MasterUserPassword: !Ref DBPassword
      MonitoringInterval: '60'
      MonitoringRoleArn: 'arn:aws:iam::123456789012:role/rds-monitoring-role'
      PubliclyAccessible: true

Positive test num. 2 - json file

{
  "Description": "Description\": \"AWS CloudFormation Sample Template for creating an Amazon RDS DB instance: Sample template showing how to create a DB instance with Enhanced Monitoring enabled. **WARNING** This template creates an RDS DB instance. You will be billed for the AWS resources used if you create a stack from this template.",
  "Parameters": {
    "DBInstanceClass": {
      "Description": "DB instance class",
      "Type": "String",
      "ConstraintDescription": "Must select a valid DB instance type.",
      "Default": "db.m5.large"
    },
    "DBAllocatedStorage": {
      "ConstraintDescription": "must be between 20 and 65536 GiB.",
      "Default": "50",
      "Description": "The size of the database (GiB)",
      "Type": "Number",
      "MinValue": "5",
      "MaxValue": "1024"
    },
    "DBUsername": {
      "MinLength": "1",
      "MaxLength": "16",
      "AllowedPattern": "[a-zA-Z][a-zA-Z0-9]*",
      "ConstraintDescription": "must begin with a letter and contain only alphanumeric characters.",
      "NoEcho": "true",
      "Description": "Username for MySQL database access",
      "Type": "String"
    },
    "DBPassword": {
      "Type": "String",
      "MinLength": "8",
      "MaxLength": "41",
      "AllowedPattern": "[a-zA-Z0-9]*",
      "ConstraintDescription": "must contain only alphanumeric characters.",
      "NoEcho": "true",
      "Description": "Password MySQL database access"
    },
    "DBInstanceID": {
      "Default": "mydbinstance",
      "Description": "My database instance",
      "Type": "String",
      "MinLength": "1",
      "MaxLength": "63",
      "AllowedPattern": "[a-zA-Z][a-zA-Z0-9]*",
      "ConstraintDescription": "Must begin with a letter and must not end with a hyphen or contain two consecutive hyphens."
    },
    "DBName": {
      "ConstraintDescription": "Must begin with a letter and contain only alphanumeric characters.",
      "Default": "mydb",
      "Description": "My database",
      "Type": "String",
      "MinLength": "1",
      "MaxLength": "64",
      "AllowedPattern": "[a-zA-Z][a-zA-Z0-9]*"
    }
  },
  "Resources": {
    "MyDB": {
      "Type": "AWS::RDS::DBInstance",
      "Properties": {
        "MasterUsername": "DBUsername",
        "MasterUserPassword": "DBPassword",
        "PubliclyAccessible": true,
        "DBInstanceIdentifier": "DBInstanceID",
        "DBName": "DBName",
        "AllocatedStorage": "DBAllocatedStorage",
        "MonitoringInterval": "60",
        "MonitoringRoleArn": "arn:aws:iam::123456789012:role/rds-monitoring-role",
        "DBInstanceClass": "DBInstanceClass",
        "Engine": "MySQL",
        "EngineVersion": "8.0.16"
      }
    }
  },
  "AWSTemplateFormatVersion": "2010-09-09T00:00:00Z"
}

Code samples without security vulnerabilities

Negative test num. 1 - yaml file

AWSTemplateFormatVersion: 2010-09-09
Description: >-
  Description": "AWS CloudFormation Sample Template for creating an Amazon RDS DB instance:
  Sample template showing how to create a DB instance with Enhanced Monitoring enabled.
  **WARNING** This template creates an RDS DB instance. You will be billed for the AWS
  resources used if you create a stack from this template.
Parameters:
  DBInstanceID:
    Default: mydbinstance
    Description: My database instance
    Type: String
    MinLength: '1'
    MaxLength: '63'
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    ConstraintDescription: >-
      Must begin with a letter and must not end with a hyphen or contain two
      consecutive hyphens.
  DBName:
    Default: mydb
    Description: My database
    Type: String
    MinLength: '1'
    MaxLength: '64'
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    ConstraintDescription: Must begin with a letter and contain only alphanumeric characters.
  DBInstanceClass:
    Default: db.m5.large
    Description: DB instance class
    Type: String
    ConstraintDescription: Must select a valid DB instance type.
  DBAllocatedStorage:
    Default: '50'
    Description: The size of the database (GiB)
    Type: Number
    MinValue: '5'
    MaxValue: '1024'
    ConstraintDescription: must be between 20 and 65536 GiB.
  DBUsername:
    NoEcho: 'true'
    Description: Username for MySQL database access
    Type: String
    MinLength: '1'
    MaxLength: '16'
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    ConstraintDescription: must begin with a letter and contain only alphanumeric characters.
  DBPassword:
    NoEcho: 'true'
    Description: Password MySQL database access
    Type: String
    MinLength: '8'
    MaxLength: '41'
    AllowedPattern: '[a-zA-Z0-9]*'
    ConstraintDescription: must contain only alphanumeric characters.
Resources:
  MyDB:
    Type: 'AWS::RDS::DBInstance'
    Properties:
      DBInstanceIdentifier: !Ref DBInstanceID
      DBName: !Ref DBName
      DBInstanceClass: !Ref DBInstanceClass
      AllocatedStorage: !Ref DBAllocatedStorage
      Engine: MySQL
      EngineVersion: 8.0.16
      MasterUsername: !Ref DBUsername
      MasterUserPassword: !Ref DBPassword
      MonitoringInterval: '60'
      MonitoringRoleArn: 'arn:aws:iam::123456789012:role/rds-monitoring-role'
      PubliclyAccessible: false

Negative test num. 2 - json file

{
  "Resources": {
    "MyDB": {
      "Type": "AWS::RDS::DBInstance",
      "Properties": {
        "AllocatedStorage": "DBAllocatedStorage",
        "EngineVersion": "8.0.16",
        "MasterUserPassword": "DBPassword",
        "MonitoringInterval": "60",
        "DBInstanceIdentifier": "DBInstanceID",
        "DBName": "DBName",
        "DBInstanceClass": "DBInstanceClass",
        "Engine": "MySQL",
        "MasterUsername": "DBUsername",
        "MonitoringRoleArn": "arn:aws:iam::123456789012:role/rds-monitoring-role",
        "PubliclyAccessible": false
      }
    }
  },
  "AWSTemplateFormatVersion": "2010-09-09T00:00:00Z",
  "Description": "Description\": \"AWS CloudFormation Sample Template for creating an Amazon RDS DB instance: Sample template showing how to create a DB instance with Enhanced Monitoring enabled. **WARNING** This template creates an RDS DB instance. You will be billed for the AWS resources used if you create a stack from this template.",
  "Parameters": {
    "DBPassword": {
      "NoEcho": "true",
      "Description": "Password MySQL database access",
      "Type": "String",
      "MinLength": "8",
      "MaxLength": "41",
      "AllowedPattern": "[a-zA-Z0-9]*",
      "ConstraintDescription": "must contain only alphanumeric characters."
    },
    "DBInstanceID": {
      "MinLength": "1",
      "MaxLength": "63",
      "AllowedPattern": "[a-zA-Z][a-zA-Z0-9]*",
      "ConstraintDescription": "Must begin with a letter and must not end with a hyphen or contain two consecutive hyphens.",
      "Default": "mydbinstance",
      "Description": "My database instance",
      "Type": "String"
    },
    "DBName": {
      "Default": "mydb",
      "Description": "My database",
      "Type": "String",
      "MinLength": "1",
      "MaxLength": "64",
      "AllowedPattern": "[a-zA-Z][a-zA-Z0-9]*",
      "ConstraintDescription": "Must begin with a letter and contain only alphanumeric characters."
    },
    "DBInstanceClass": {
      "Default": "db.m5.large",
      "Description": "DB instance class",
      "Type": "String",
      "ConstraintDescription": "Must select a valid DB instance type."
    },
    "DBAllocatedStorage": {
      "Description": "The size of the database (GiB)",
      "Type": "Number",
      "MinValue": "5",
      "MaxValue": "1024",
      "ConstraintDescription": "must be between 20 and 65536 GiB.",
      "Default": "50"
    },
    "DBUsername": {
      "MinLength": "1",
      "MaxLength": "16",
      "AllowedPattern": "[a-zA-Z][a-zA-Z0-9]*",
      "ConstraintDescription": "must begin with a letter and contain only alphanumeric characters.",
      "NoEcho": "true",
      "Description": "Username for MySQL database access",
      "Type": "String"
    }
  }
}