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Cis AWS Euc 2.4

DevOps & Security
cis-aws-euc-2.4

Cis AWS Euc 2.4 is an Agent Skill for devops & security published in the CyberStrikeus/CyberStrike repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

Ensure WorkSpaces are deployed in their own virtual private cloud (VPC)

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Ensure WorkSpaces are deployed in their own virtual private cloud (VPC) (Manual)

Profile Applicability

  • Level 1

Description

Amazon WorkSpaces VPC should be created with two private subnets for your WorkSpaces and a NAT gateway in a public subnet.

Rationale

The NAT gateway will provide WorkSpaces access to the internet for updates to the operating system and so that applications can be deployed using Amazon WorkSpaces Application Manager if that is applicable for your environment.

Impact

Your VPC's subnets must be in different Availability Zones in the Region where you're launching WorkSpaces.

Audit Procedure

Using AWS Console

Perform the following steps to confirm that a VPC exists for WorkSpaces and is configured correctly:

  1. Login to the VPC console at https://console.aws.amazon.com/vpc/
  2. In the left pane, click Your VPC's
  3. Select the VPC for WorkSpaces
  4. Confirm the IPv4 settings are using a CIDR block from the private (non-publicly routable) IP address ranges. For example, 10.0.0.0/16. For more information, see the references below
  5. Confirm the IPv6 CIDR Block, set to No
  6. Confirm the IPv4 CIDR block for the public subnet (example - WorkSpaces Public Subnet)
    • Availability Zone, set to No Preference
  7. Confirm the IPv4 CIDR block for the first private subnet (example - WorkSpaces Private Subnet 1)
    • Availability Zone, set for Amazon WorkSpaces
    • Elastic IP Allocation ID
    • Service endpoints - Blank
    • Enable DNS hostnames, set to Yes
    • Hardware tenancy, Default
  8. Confirm the IPv4 CIDR block for the first private subnet (example - WorkSpaces Private Subnet 2)
    • Availability Zone set for Amazon WorkSpaces
      • NOTE: Make sure you select a different Availability zone from the one you selected for the Workspaces Private Subnet 1
    • Elastic IP Allocation ID
    • Service endpoints - Blank
    • Enable DNS hostnames, set to Yes
    • Hardware tenancy, Default

If this is not set as referenced above refer to the remediation procedure below.

Remediation

Using AWS Console

Allocate an Elastic IP Address

  1. Login in to the VPC console at https://console.aws.amazon.com/vpc/
  2. In the left pane, click Elastic IPs
  3. Click Allocate new address
  4. On the Allocate new address page, for IPv4 address pool, click Amazon pool or Owned by me
  5. Click Allocate
  6. Make a note of the Elastic IP address, click Close

Create a VPC with one public subnet and two private subnets as follows:

  1. Login in to the VPC console at https://console.aws.amazon.com/vpc/

  2. In the left pane, click VPC Dashboard in the upper-left corner

  3. Click Launch VPC Wizard

  4. Click VPC with Public and Private Subnets

  5. Click Select

  6. Configure the VPC as follows:

    • For IPv4 CIDR block, enter the CIDR block from the private (non-publicly routable) IP address ranges. For example 10.0.0.0/16
    • For IPv6 CIDR block, keep No IPv6 CIDR Block
    • For VPC name, enter a name for the VPC (example: WorkspacesVPC)
    • For Public subnet's IPv4 CIDR - enter a CIDR block from the private (non-publicly routable) IP address ranges. For example - 10.0.0.0/24
    • For Availability Zone, keep No Preference
    • For Public subnet name, enter a name for the subnet (example: WorkSpaces Public Subnet)
    • For Private subnet's IPv4 CIDR, enter the CIDR block for the subnet
    • Availability Zone - Accept the default value = No Preference
    • For Private subnet name, enter a name for the subnet (example: WorkSpaces Private Subnet 1)
    • For Elastic IP Allocation ID, enter the Elastic IP address that you created
    • For Service endpoints, do nothing
    • For Enable DNS hostnames, keep Yes
    • For Hardware tenancy, keep Default

  7. Click Create VPC. Note that it takes several minutes to set up your VPC. After the VPC is created

  8. Click OK

Create a Second Private Subnet

  1. In the left pane, click Subnets
  2. Click Create Subnet
    • For Name tag, enter a name for the private subnet (example: WorkSpaces Private Subnet 2)
    • For VPC, select the VPC that you created
    • For Availability Zone. Make sure you select a different Availability Zone from the one you used in WorkSpaces Private Subnet 1
    • For IPv4 CIDR block, enter the CIDR block for the subnet
  3. Click Create

Verify and Name the Route Tables for Public

  1. In the left pane, click Subnets
  2. Click the public subnet that you created. (example: WorkSpaces Public Subnet)
  3. On the Route Table tab, choose the ID of the route table (example: rtb-12345678)
  4. Click the route table
  5. Under Name, choose the edit icon, enter a name (example: workspaces-public-routetable)
  6. Click the check mark to save the name

Verify and Name the Route Tables for Private

  1. In the left pane, click Subnets
  2. Click the private subnet 1 that you created. (example: WorkSpaces Private Subnet 1)
  3. On the Route Table tab, choose the ID of the route table (example: rtb-12345678)
  4. Click the route table
  5. Under Name, choose the edit icon, enter a name (example: workspaces-private-routetable)
  6. Click the check mark to save the name
  7. On the Routes tab, verify that there is one route for local traffic and another route that sends all other traffic to the internet gateway for the VPC
  8. Repeat steps 1-7 under Verify and Name the Route Tables for Private for WorkSpaces Private Subnet 2'

Default Value

By default, AWS Workspaces does not create its own VPC. A VPC must be created to run an AWS Workspace environment.

References

  1. https://docs.aws.amazon.com/workspaces/latest/adminguide/amazon-workspaces-vpc.html
  2. https://docs.aws.amazon.com/vpc/latest/userguide/VPC_Subnets.html#vpc-sizing-ipv4
  3. https://docs.aws.amazon.com/workspaces/latest/adminguide/azs-workspaces.html

CIS Controls

v8:

  • 3.12 Segment Data Processing and Storage Based on Sensitivity
    • Segment data processing and storage based on the sensitivity of the data. Do not process sensitive data on enterprise assets intended for lower sensitivity data.

v7:

  • 14.1 Segment the Network Based on Sensitivity
    • Segment the network based on the label or classification level of the information stored on the servers, locate all sensitive information on separated Virtual Local Area Networks (VLANs).