An Amazon S3 bucket is created without server-side encryption. Encryption mitigates data breaches by making data unreadable to anyone without the proper credentials. Encryption at rest can help satisfy some industrial and government compliance requirements such as GDPR, HIPAA, and PCI.

AWS API Gateway methods that are publicly accessible can expose the organization to attack.

Example 1: The following example template defines publicly accessible AWS API Gateway methods.

{
    "AWSTemplateFormatVersion": "2010-09-09",
    "Resources": {
        "MyMethod0": {
            "Type": "AWS::ApiGateway::Method",
            "Properties": {
                "RestApiId": "MyAPIID",
                "ResourceId": "MyResourceID",
                "HttpMethod": "GET",
                "AuthorizationType": "NONE"
            }
        },
        "MyMethod1": {
            "Type": "AWS::ApiGateway::Method",
            "Properties": {
                "RestApiId": "MyAPIID",
                "ResourceId": "MyResourceID",
                "HttpMethod": "POST",
                "AuthorizationType": "NONE",
                "ApiKeyRequired": false
            }
        }
    }
}

A wildcard configuration for lambda principals violates the least privilege principle and allows an attacker to invoke the lambda from any account.

Example 1: The following example template defines a wildcard lambda principal.

{
    "Resources": {
        "LambdaPerm": {
            "Type": "AWS::Lambda::Permission",
            "Properties": {
            "SourceAccount": "AWS::AccountId",
            "SourceArn": "bucket.Arn",
            "FunctionName": "function.Arn",
            "Action": "lambda:InvokeFunction",
            "Principal": "*"
            }
        }
    },
    "AWSTemplateFormatVersion": "2010-09-09",
    "Description": "Lambda Permission"
}

By default, Amazon DocumentDB instances are not encrypted. This exposes the data to unauthorized access and potential theft.

Example 1: The following example shows a template that defines an Amazon DocumentDB with encryption disabled.

"Resources": {
    "DocDBDefault": {
        "Type": "AWS::DocDB::DBCluster",
        "Properties": {
            "MasterUsername": "name",
            "MasterUserPassword": "password"
        }
    }

By default, EBS volumes are not encrypted.
Example 1: The following example template exposes the data to potential theft and unauthorized access.

"Resources": {
    "EBSVOLExample": {
        "Type": "AWS::EC2::Volume",
        "Properties": {
            "Encrypted": false,
        }
    }
}

By default, Amazon ElastiCache Replication Groups are not encrypted. This exposes the data to unauthorized access and potential theft.

Example 1: The following example template defines an Amazon ElastiCache Replication Group with encryption disabled.

{
    "Description": "ElastiCache redis",
    "Resources": {
        "MyReplicationGroup": {
            "Type": "AWS::ElastiCache::ReplicationGroup",
            "Properties": {
                "AutomaticFailoverEnabled": true,
                "CacheNodeType": {
                    "Ref": "CacheNodeType"
                },
                Cache  "ParameterGroupName": {
                    "Ref": "CacheParameterGroup"
                },
                "CacheSubnetGroupName": {
                    "Ref": "CacheSubnetGroupName"
                },
                "Engine": "redis",
                "EngineVersion": {
                    "Ref": "EngineVersion"
                },
                "NumNodeGroups": {
                    "Ref": "NumShards"
                },
                "ReplicasPerNodeGroup": {
                    "Ref": "NumReplicas"
                },
                "PreferredMaintenanceWindow": "sat:10:00-sat:08:00",
                "SecurityGroupIds": [
                    {
                        "Ref": "SecurityGroup"
                    }
                ],
                "SnapshotRetentionLimit": {
                    "Ref": "SnapshotRetentionLimit"
                },
                "SnapshotWindow": "00:00-03:00"
            },
            "UpdatePolicy": {
                "UseOnlineResharding": true
            }
        }
    }
}

By default, Neptune DB clusters are not encrypted. This exposes the data to potential theft and unauthorized access by attackers.

Example 1: The following example template fails to enable encryption at rest.

{
    "AWSTemplateFormatVersion": "2010-09-09",
    "Description": "My Neptune DB cluster",
    "Resources": {
        "NeptuneDBCluster": {
            "Type": "AWS::Neptune::DBCluster",
            "Properties": {
                "BackupRetentionPeriod": 10,
                "DBClusterIdentifier": "MyDBClusterIdentifier",
                "DBClusterParameterGroupName": "MyNeptuneDBClusterParameterGroup",
                "DBSubnetGroupName": "MyNeptuneDBSubnetGroup",
                "IamAuthEnabled": true,
                "Port": 8080,
                "PreferredBackupWindow": "NeptuneDBClusterPreferredBackupWindow",
                "PreferredMaintenanceWindow": "NeptuneDBClusterPreferredMaintenanceWindow"
            }
        }
    }
}