EC2 Instance Dedicated Tenancy

Risk Level: Medium (should be achieved)

Rule ID: EC2-053

Ensure that all the dedicated Amazon EC2 instances provisioned within your AWS cloud account are regularly reviewed for cost optimization. Dedicated instances are Amazon EC2 compute resources which run on single-tenant hardware (i.e., physically isolated at the host level).

This rule can help you with the following compliance standards:

NIST4

For further details on compliance standards supported by Conformity, see here.

This rule resolution is part of the Conformity Security & Compliance tool for AWS.

Cost
optimisation

Because dedicated EC2 instances are physically isolated at the host hardware level from instances provisioned in other AWS accounts, these are more expensive than the ones running on the shared (default) environment.

Audit

To identify dedicated Amazon EC2 instances running within your AWS cloud account for review purposes, perform the following operations:

Using AWS Console

01 Sign in to the AWS Management Console.

02 Navigate to Amazon EC2 console available at https://console.aws.amazon.com/ec2/.

03 In the left navigation panel, under Instances, choose Instances.

04 Select the Amazon EC2 instance that you want to examine.

05 Choose the Details tab from the console split panel to access the instance configuration information.

06 In the Host and placement group section, check the Tenancy configuration attribute value to determine the tenancy type for the selected instance. If the attribute value is set to default, the selected EC2 instance is running on Multi-Tenant Hardware (logically isolated). If the Tenancy value is set to dedicated, the selected EC2 instance is running on Single-Tenant Hardware (physically isolated at the host hardware level) and can be reviewed for cost optimization.

07 Repeat steps no. 4 – 6 for each Amazon EC2 instance available within the current AWS cloud region.

08 Change the AWS cloud region from the console navigation bar and repeat the Audit process for other regions.

Using AWS CLI

01 Run describe-instances command (OSX/Linux/UNIX) with custom output filters to list the IDs of the Amazon EC2 instances provisioned in the selected AWS cloud region:

aws ec2 describe-instances
	--region us-east-1
	--output table
	--query 'Reservations[*].Instances[*].InstanceId'

02 The command output should return a table with the requested EC2 instance identifiers (IDs):

-------------------------
|   DescribeInstances   |
+-----------------------+
|  i-01234abcd1234abcd  |
|  i-0abcdabcdabcdabcd  |
|  i-0abcd1234abcd1234  |
+-----------------------+

03 Run describe-instances command (OSX/Linux/UNIX) with the ID of the Amazon EC2 instance that you want to examine as the identifier parameter and custom output filters to describe the type of tenancy used by the selected EC2 instance:

aws ec2 describe-instances
	--region us-east-1
	--instance-ids i-01234abcd1234abcd
	--query 'Reservations[*].Instances[*].Placement.Tenancy[]'

04 The command output should return the type of the tenancy configured for the selected EC2 instance:

If the command output returns "default", your Amazon EC2 instance is running on a Multi-Tenant Hardware (logically isolated):
```
[
	"default"
]
```
If the describe-instances command output returns "dedicated", your Amazon EC2 instance is running on a Single-Tenant Hardware (physically isolated):
```
[
	"dedicated"
]
```
If the command output returns "host", your EC2 instance is running on a Single-Tenant Hardware (physically isolated) that gives you full control over the instance placement at the host level:
```
[
	"host"
]
```

If the describe-instances command output returns "dedicated", the selected Amazon EC2 instance is dedicated (physically isolated at the host hardware level), therefore, the instance can be reviewed for cost optimization.

05 Repeat steps no. 3 and 4 for each Amazon EC2 instance available in the selected AWS region.

06 Change the AWS cloud region by updating the --region command parameter value and repeat the Audit process for other regions.

Remediation / Resolution

Case A: After the dedicated instance is reviewed, you can choose to migrate your EC2 instance to the default (shared) tenancy in order to reduce your Amazon EC2 service costs. To relaunch (re-create) your dedicated Amazon EC2 instance with the appropriate tenancy type, perform the following operations:

Using AWS CloudFormation

01 CloudFormation template (JSON):

{
	"AWSTemplateFormatVersion":"2010-09-09",
	"Description":"Create EC2 instance with Default Tenancy model",
	"Parameters":{
		"InstanceKeyName":{
			"Type":"AWS::EC2::KeyPair::KeyName",
			"Description":"The SSH key used to access the instance."
		},
		"InstanceSecurityGroup":{
			"Type":"AWS::EC2::SecurityGroup::Id",
			"Description":"The ID of the security group to use."
		}
	},
	"Resources":{
		"EncryptedEC2Instance":{
			"Type":"AWS::EC2::Instance",
			"Properties":{
			"ImageId":"ami-0abcd1234abcd1234",
			"InstanceType":"t2.micro",
			"KeyName":{
				"Ref":"InstanceKeyName"
			},
			"SubnetId":"subnet-abcd1234",
			"SecurityGroupIds":[
				{
					"Ref":"InstanceSecurityGroup"
				}
			],
			"BlockDeviceMappings":[
				{
					"DeviceName":"/dev/xvda",
					"Ebs":{
						"VolumeSize":"150",
						"VolumeType":"gp2"
					}
				}
			],
			"Tenancy":"default"
			}
		}
	}
}

02 CloudFormation template (YAML):

AWSTemplateFormatVersion: '2010-09-09'
	Description: Create EC2 instance with Default Tenancy model
	Parameters:
		InstanceKeyName:
		Type: AWS::EC2::KeyPair::KeyName
		Description: The SSH key used to access the instance.
		InstanceSecurityGroup:
		Type: AWS::EC2::SecurityGroup::Id
		Description: The ID of the security group to use.
	Resources:
		EncryptedEC2Instance:
		Type: AWS::EC2::Instance
		Properties:
			ImageId: ami-0abcd1234abcd1234
			InstanceType: t2.micro
			KeyName:
			Ref: InstanceKeyName
			SubnetId: subnet-abcd1234
			SecurityGroupIds:
			- Ref: InstanceSecurityGroup
			BlockDeviceMappings:
			- DeviceName: "/dev/xvda"
			Ebs:
				VolumeSize: '150'
				VolumeType: gp2
			Tenancy: default

Using Terraform (AWS Provider)

01 Terraform configuration file (.tf):

terraform {
	required_providers {
		aws = {
			source  = "hashicorp/aws"
			version = "~> 3.27"
		}
	}

	required_version = ">= 0.14.9"
}

provider "aws" {
	profile = "default"
	region  = "us-east-1"
}

resource "aws_instance" "new-ec2-instance" {

	ami = "ami-0abcd1234abcd1234"
	instance_type = "t2.micro"
	key_name = "ssh-key"
	subnet_id = "subnet-abcd1234"
	vpc_security_group_ids = [ "sg-01234abcd1234abcd" ]

	ebs_block_device {
		device_name = "/dev/xvda"
		volume_size = 150
		volume_type = "gp2"
	}

	tenancy = "default"

	lifecycle {
		ignore_changes = [ami]
	}

}

Using AWS Console

01 Sign in to the AWS Management Console.

02 Navigate to Amazon EC2 console available at https://console.aws.amazon.com/ec2/.

03 In the left navigation panel, under Instances, choose Instances.

04 Select the Amazon EC2 instance that you want to re-create.

05 Choose Actions from the top-right menu, select Image and templates, and choose Create image.

06 On the Create image setup page, provide the following information:

For Image name, type a unique name for your new Amazon Machine Image (AMI).
(Optional) For Image description - optional, provide a short description that reflects the usage of the selected EC2 instance.
Select the Reboot instance setting checkbox to ensure data consistency. When this option is selected, Amazon EC2 reboots the instance so that data is at rest when snapshots of the attached volumes are taken.
(Optional) For Tags - optional, choose Tag image and snapshots together, and use the Add new tag button to create and apply user-defined tags to the new image. Tags can be used to search and filter your cloud resources or track your AWS costs.
Choose Create image to create your new AMI.

07 In the left navigation panel, under Images, select AMIs, and check the Status column to determine the state of your new AMI. Once the Status is set to Available, the image is ready to be used to relaunch your Amazon EC2 instance with the correct tenancy type.

08 In the left navigation panel, under Instances, select Instances, choose Launch instances, and perform the following actions to launch your new EC2 instance:

For Name and tags, provide a name tag for your instance in the Name box. (Optional) Choose Add additional tags to apply user-defined tags to your new EC2 instance. You can track compute cost and other criteria by tagging your instance.
For Application and OS Images (Amazon Machine Image), select My AMIs tab, choose Owned by me, and select the name of the AMI created in step no. 6 from the Amazon Machine Image (AMI) dropdown list.
For Instance type, select the required instance type from the Instance type dropdown list (must match the hardware configuration of the source instance).
For Key pair (login), you can select the same key pair as the source instance from the Key pair name - required dropdown list or choose Create new key pair to create a new key pair for your instance.
For Network settings, choose Select existing security group under Firewall (security groups), and select the appropriate security group(s) from the Common security groups dropdown list (must match the security group configuration of the source instance). If you need to change the VPC network settings, choose Edit, and make sure the network settings align with the source instance settings.
For Configure storage, configure the storage device settings (must match the storage configuration of the source instance).
For Advanced details, configure the advanced settings supported by your EC2 instance. For Tenancy, select Shared - run a shared hardware instance to deploy the new EC2 instance in a logically isolated hardware environment (i.e., Shared Instance). This will help your reduce your Amazon EC2 service fees.
For Summary, review the instance details, and choose Launch instance to deploy your new, compliant Amazon EC2 instance.
Choose View all instances to view your new EC2 instance. Once the Instance State is set to Running, your new instance is ready to use.

09 (Optional) To stop incurring any charges for your non-compliant (source) instance, you must terminate it. To shut down the instance, perform the following actions:

In the left navigation panel, under Instances, choose Instances.
Select the Amazon EC2 instance that you want to terminate.
Choose Instance state and select Terminate (delete) instance.
In the Terminate (delete) instance confirmation box, review the instance details, then choose Terminate (delete) to terminate the selected EC2 instance.

10 Repeat steps no. 2 – 9 for each Amazon EC2 instance that you want to re-create, available within the current AWS cloud region.

11 Change the AWS cloud region from the console navigation bar and repeat the Remediation process for other regions.

Using AWS CLI

01 Run describe-instances command (OSX/Linux/UNIX) to list the configuration information for the Amazon EC2 instance that you want to re-create (i.e., source instance):

aws ec2 describe-instances
	--region us-east-1
	--instance-ids i-01234abcd1234abcd
	--query 'Reservations[*].Instances[]'

02 The command output should return the configuration information necessary for re-creating your Amazon EC2 instance:

[
	{
		"Architecture": "x86_64",
		"BlockDeviceMappings": [
			{
				"DeviceName": "/dev/xvda",
				"Ebs": {
					"AttachTime": "2025-07-01T11:00:32+00:00",
					"DeleteOnTermination": true,
					"Status": "attached",
					"VolumeId": "vol-0abcd1234abcd1234"
				}
			}
		],
		"EbsOptimized": false,
		"EnaSupport": true,
		"Hypervisor": "xen",
		"NetworkInterfaces": [
			{
				"Association": {
					"IpOwnerId": "amazon",
					"PublicDnsName": "ec2-xxx-xxx-xxx-xxx.compute-1.amazonaws.com",
					"PublicIp": "xxx.xxx.xxx.xxx"
				},
				"Attachment": {
					"AttachTime": "2025-07-01T11:00:31+00:00",
					"AttachmentId": "eni-attach-01234abcd1234abcd",
					"DeleteOnTermination": true,
					"DeviceIndex": 0,
					"Status": "attached",
					"NetworkCardIndex": 0
				},
				"Description": "",
				"Groups": [
					{
						"GroupId": "sg-0abcd1234abcd1234",
						"GroupName": "cc-project5-security-group"
					}
				],
				"Ipv6Addresses": [],
				"NetworkInterfaceId": "eni-01234abcd1234abcd",
				"OwnerId": "123456789012",
				"PrivateDnsName": "ip-172-10-20-30.ec2.internal",
				"PrivateIpAddress": "172.10.20.30",
				"PrivateIpAddresses": [
					{
						"Association": {
							"IpOwnerId": "amazon",
							"PublicDnsName": "ec2-xxx-xxx-xxx-xxx.compute-1.amazonaws.com",
							"PublicIp": "xxx.xxx.xxx.xxx"
						},
						"Primary": true,
						"PrivateDnsName": "ip-172-10-20-30.ec2.internal",
						"PrivateIpAddress": "172.10.20.30"
					}
				],
				"SourceDestCheck": true,
				"Status": "in-use",
				"SubnetId": "subnet-01234abcd1234abcd",
				"VpcId": "vpc-0abcd1234abcd1234",
				"InterfaceType": "interface",
				"Operator": {
					"Managed": false
				}
			}
		],
		"RootDeviceName": "/dev/xvda",
		"RootDeviceType": "ebs",
		"SecurityGroups": [
			{
				"GroupId": "sg-0abcd1234abcd1234",
				"GroupName": "cc-project5-security-group"
			}
		],
		"SourceDestCheck": true,
		"Tags": [
			{
				"Key": "Name",
				"Value": "cc-project5-prod-instance"
			}
		],
		"VirtualizationType": "hvm",
		"CpuOptions": {
			"CoreCount": 1,
			"ThreadsPerCore": 1
		},
		"CapacityReservationSpecification": {
			"CapacityReservationPreference": "open"
		},
		"HibernationOptions": {
			"Configured": false
		},
		"MetadataOptions": {
			"State": "applied",
			"HttpTokens": "required",
			"HttpPutResponseHopLimit": 2,
			"HttpEndpoint": "enabled",
			"HttpProtocolIpv6": "disabled",
			"InstanceMetadataTags": "disabled"
		},
		"EnclaveOptions": {
			"Enabled": false
		},
		"BootMode": "uefi-preferred",
		"PlatformDetails": "Linux/UNIX",
		"UsageOperation": "RunInstances",
		"UsageOperationUpdateTime": "2025-07-01T11:00:31+00:00",
		"PrivateDnsNameOptions": {
			"HostnameType": "ip-name",
			"EnableResourceNameDnsARecord": true,
			"EnableResourceNameDnsAAAARecord": false
		},
		"MaintenanceOptions": {
			"AutoRecovery": "default",
			"RebootMigration": "default"
		},
		"CurrentInstanceBootMode": "legacy-bios",
		"NetworkPerformanceOptions": {
			"BandwidthWeighting": "default"
		},
		"Operator": {
			"Managed": false
		},
		"InstanceId": "i-01234abcd1234abcd",
		"ImageId": "ami-0abcd1234abcd1234",
		"State": {
			"Code": 16,
			"Name": "running"
		},
		"PrivateDnsName": "ip-172-10-20-30.ec2.internal",
		"PublicDnsName": "ec2-xxx-xxx-xxx-xxx.compute-1.amazonaws.com",
		"StateTransitionReason": "",
		"KeyName": "cc-project5-ssh-key",
		"AmiLaunchIndex": 0,
		"ProductCodes": [],
		"InstanceType": "t2.micro",
		"LaunchTime": "2025-07-01T10:01:31+00:00",
		"Placement": {
			"GroupName": "",
			"Tenancy": "default",
			"AvailabilityZone": "us-east-1a"
		},
		"Monitoring": {
			"State": "disabled"
		},
		"SubnetId": "subnet-01234abcd1234abcd",
		"VpcId": "vpc-0abcd1234abcd1234",
		"PrivateIpAddress": "172.10.20.30",
		"PublicIpAddress": "xxx.xxx.xxx.xxx"
	}
]

03 Run create-image command (OSX/Linux/UNIX) to create an Amazon Machine Image (AMI) from the source Amazon EC2 instance described in the previous step. Include the --no-reboot command parameter to ensure data consistency. When this parameter is included, Amazon EC2 reboots the instance so that data is at rest when snapshots of the attached volumes are taken:

aws ec2 create-image
	--region us-east-1
	--instance-id i-01234abcd1234abcd
	--name "Project5 Prod Instance AMI"
	--description "Production Stack AMI version 2.0"
	--no-reboot

04 The command output should return the ID of the new Amazon Machine Image (AMI):

{
	"ImageId": "ami-0abcdabcdabcdabcd"
}

05 Perform run-instances command (OSX/Linux/UNIX) to launch a new Amazon EC2 instance from the AMI created in the previous steps. Use the information returned in step no. 2 to configure your new EC2 instance. Set the --placement parameter to: Tenancy=default to use the Default Tenancy model (i.e., logically isolated hardware environment). This will help your reduce your Amazon EC2 service fees:

aws ec2 run-instances
	--region us-east-1
	--image-id ami-0abcdabcdabcdabcd
	--count 1
	--instance-type t2.micro
	--key-name cc-project5-ssh-key
	--security-group-ids sg-0abcd1234abcd1234
	--tag-specifications 'ResourceType=instance,Tags=[{Key=Name,Value=cc-project5-prod-instance}]'
	--placement Tenancy=default
	--query 'Instances[]'

06 The command output should return the configuration information for the newly created EC2 instance:

[
	{
		"Architecture": "x86_64",
		"BlockDeviceMappings": [],
		"EbsOptimized": false,
		"EnaSupport": true,
		"Hypervisor": "xen",
		"NetworkInterfaces": [
			{
				"Attachment": {
					"AttachTime": "2025-07-01T11:50:48+00:00",
					"AttachmentId": "eni-attach-01234abcd1234abcd",
					"DeleteOnTermination": true,
					"DeviceIndex": 0,
					"Status": "attaching",
					"NetworkCardIndex": 0
				},
				"Description": "",
				"Groups": [
					{
						"GroupId": "sg-0abcd1234abcd1234",
						"GroupName": "cc-project5-security-group"
					}
				],
				"Ipv6Addresses": [],
				"NetworkInterfaceId": "eni-01234abcd1234abcd",
				"OwnerId": "123456789012",
				"PrivateDnsName": "ip-172-20-30-40.ec2.internal",
				"PrivateIpAddress": "172.20.30.40",
				"PrivateIpAddresses": [
					{
						"Primary": true,
						"PrivateDnsName": "ip-172-20-30-40.ec2.internal",
						"PrivateIpAddress": "172.20.30.40"
					}
				],
				"SourceDestCheck": true,
				"Status": "in-use",
				"SubnetId": "subnet-01234abcd1234abcd",
				"VpcId": "vpc-0abcd1234abcd1234",
				"InterfaceType": "interface",
				"Operator": {
					"Managed": false
				}
			}
		],
		"RootDeviceName": "/dev/xvda",
		"RootDeviceType": "ebs",
		"SecurityGroups": [
			{
				"GroupId": "sg-0abcd1234abcd1234",
				"GroupName": "cc-project5-security-group"
			}
		],
		"SourceDestCheck": true,
		"StateReason": {
			"Code": "pending",
			"Message": "pending"
		},
		"Tags": [
			{
				"Key": "Name",
				"Value": "cc-project5-prod-instance"
			}
		],
		"VirtualizationType": "hvm",
		"CpuOptions": {
			"CoreCount": 1,
			"ThreadsPerCore": 1
		},
		"CapacityReservationSpecification": {
			"CapacityReservationPreference": "open"
		},
		"MetadataOptions": {
			"State": "pending",
			"HttpTokens": "required",
			"HttpPutResponseHopLimit": 2,
			"HttpEndpoint": "enabled",
			"HttpProtocolIpv6": "disabled",
			"InstanceMetadataTags": "disabled"
		},
		"EnclaveOptions": {
			"Enabled": false
		},
		"BootMode": "uefi-preferred",
		"PrivateDnsNameOptions": {
			"HostnameType": "ip-name",
			"EnableResourceNameDnsARecord": false,
			"EnableResourceNameDnsAAAARecord": false
		},
		"MaintenanceOptions": {
			"AutoRecovery": "default",
			"RebootMigration": "default"
		},
		"CurrentInstanceBootMode": "legacy-bios",
		"Operator": {
			"Managed": false
		},
		"InstanceId": "i-0abcd1234abcd1234",
		"ImageId": "ami-0abcdabcdabcdabcd",
		"State": {
			"Code": 0,
			"Name": "pending"
		},
		"PrivateDnsName": "ip-172-20-30-40.ec2.internal",
		"PublicDnsName": "",
		"StateTransitionReason": "",
		"KeyName": "cc-project5-ssh-key",
		"AmiLaunchIndex": 0,
		"ProductCodes": [],
		"InstanceType": "t2.micro",
		"LaunchTime": "2025-07-01T11:50:48+00:00",
		"Placement": {
			"GroupName": "",
			"Tenancy": "default",
			"AvailabilityZone": "us-east-1a"
		},
		"Monitoring": {
			"State": "disabled"
		},
		"SubnetId": "subnet-01234abcd1234abcd",
		"VpcId": "vpc-0abcd1234abcd1234",
		"PrivateIpAddress": "172.20.30.40"
	}
]

07 (Optional) You can terminate the source (non-compliant) EC2 instance in order to stop incurring charges for it. To shut down the instance, run terminate-instances command (OSX/Linux/UNIX) with the source instance ID as the identifier parameter:

aws ec2 terminate-instances
	--region us-east-1
	--instance-ids i-01234abcd1234abcd

08 The output should return the terminate-instances command request information:

{
	"TerminatingInstances": [
		{
			"InstanceId": "i-01234abcd1234abcd",
			"CurrentState": {
				"Code": 32,
				"Name": "shutting-down"
			},
			"PreviousState": {
				"Code": 16,
				"Name": "running"
			}
		}
	]
}

09 Repeat steps no. 1 – 8 for each Amazon EC2 instance that you want to re-create, available in the selected AWS cloud region.

10 Change the AWS cloud region by updating the --region command parameter value and repeat the Remediation process for other regions.

Case B: After the instance is reviewed, choose to keep the dedicated tenancy type for your Amazon EC2 instance. In this case, your Amazon EC2 instance is dedicated by design in order to meet regulatory compliance and standards within your organization.

References

CloudFormation Documentation
Amazon Elastic Compute Cloud resource type reference

AWS Command Line Interface (CLI) Documentation
describe-instances
create-image
run-instances
terminate-instances

Terraform Documentation
AWS Provider

Publication date Mar 13, 2017

Audit

Using AWS Console

Using AWS CLI

Remediation / Resolution

Using AWS CloudFormation

Using Terraform (AWS Provider)

Using AWS Console

Using AWS CLI

References

Related EC2 rules