Terraform AWS Secure Baseline : To Set Up Your AWS Account

Terraform Aws Secure Baseline is a terraform module to set up your AWS account with the secure baseline configuration based on CIS Amazon Web Services Foundations.

Terraform Module Registry

A terraform module to set up your AWS account with the reasonably secure configuration baseline. Most configurations are based on CIS Amazon Web Services Foundations v1.2.0.

Starting from v0.10.0, this module requires Terraform v0.12 or later. Please use v0.9.0 if you need to use Terraform v0.11 or ealier.

Features

1 . Identity and Access Management:

• Set up IAM Password Policy.
• Create separated IAM roles for defining privileges and assigning them to entities such as IAM users and groups.
• Create an IAM role for contacting AWS support for incident handling.
• Enable AWS Config rules to audit root account status.

2. Logging & Monitoring:

• Enable CloudTrail in all regions and deliver events to CloudWatch Logs.
• CloudTrail logs are encrypted using AWS Key Management Service.
• All logs are stored in the S3 bucket with access logging enabled.
• Logs are automatically archived into Amazon Glacier after the given period(defaults to 90 days).
• Set up CloudWatch alarms to notify you when critical changes happen in your AWS account.
• Enable AWS Config in all regions to automatically take configuration snapshots.
• Enable SecurityHub and subscribe CIS benchmark standard.

3. Networking:

• Remove all rules associated with default route tables, default network ACLs and default security groups in the default VPC in all regions.
• Enable AWS Config rules to audit unrestricted common ports in Security Group rules.
• Enable VPC Flow Logs with the default VPC in all regions.
• Enable GuardDuty in all regions.

Also Read – SKA : Simple Karma Attack

Usage

data “aws_caller_identity” “current” {}
data “aws_region” “current” {}

module “secure_baseline” {
source = “nozaq/secure-baseline/aws”

audit_log_bucket_name = “YOUR_BUCKET_NAME”
aws_account_id = data.aws_caller_identity.current.account_id
region = data.aws_region.current.name
support_iam_role_principal_arn = “YOUR_IAM_USER”

providers = {
aws = aws
aws.ap-northeast-1 = aws.ap-northeast-1
aws.ap-northeast-2 = aws.ap-northeast-2
aws.ap-south-1 = aws.ap-south-1
aws.ap-southeast-1 = aws.ap-southeast-1
aws.ap-southeast-2 = aws.ap-southeast-2
aws.ca-central-1 = aws.ca-central-1
aws.eu-central-1 = aws.eu-central-1
aws.eu-north-1 = aws.eu-north-1
aws.eu-west-1 = aws.eu-west-1
aws.eu-west-2 = aws.eu-west-2
aws.eu-west-3 = aws.eu-west-3
aws.sa-east-1 = aws.sa-east-1
aws.us-east-1 = aws.us-east-1
aws.us-east-2 = aws.us-east-2
aws.us-west-1 = aws.us-west-1
aws.us-west-2 = aws.us-west-2
}
}

Check the example to understand how these providers are defined. Note that you need to define a provider for each AWS region and pass them to the module.

Currently this is the recommended way to handle multiple regions in one module. Detailed information can be found at Providers within Modules – Terraform Docs.

A new S3 bucket to store audit logs is automatically created by default, while the external S3 bucket can be specified.

It is useful when you already have a centralized S3 bucket to store all logs. Please see external-bucket example for more detail.

Managing multiple accounts in AWS Organization

When you have multiple AWS accounts in your AWS Organization, secure-baseline module configures the separated environment for each AWS account.

You can change this behavior to centrally manage security information and audit logs from all accounts in one master account.

Check organization example for more detail.

Submodules

This module is composed of several submodules and each of which can be used independently. Modules in Package Sub-directories – Terraform describes how to source a submodule.

• alarm-baseline
• cloudtrail-baseline
• guardduty-baseline
• iam-baseline
• vpc-baseline
• secure-bucket

Inputs

Name	Description	Type	Default	Required
account_type	The type of the AWS account. The possible values are individual, master and member . Specify master and member to set up centalized logging for multiple accounts in AWS Organization. Use individual` otherwise.	string	"individual"	no
alarm_namespace	The namespace in which all alarms are set up.	string	"CISBenchmark"	no
alarm_sns_topic_name	The name of the SNS Topic which will be notified when any alarm is performed.	string	"CISAlarm"	no
allow_users_to_change_password	Whether to allow users to change their own password.	string	"true"	no
audit_log_bucket_force_destroy	A boolean that indicates all objects should be deleted from the audit log bucket so that the bucket can be destroyed without error. These objects are not recoverable.	string	"false"	no
audit_log_bucket_name	The name of the S3 bucket to store various audit logs.	string	n/a	yes
audit_log_lifecycle_glacier_transition_days	The number of days after log creation when the log file is archived into Glacier.	string	"90"	no
aws_account_id	The AWS Account ID number of the account.	string	n/a	yes
cloudtrail_cloudwatch_logs_group_name	The name of CloudWatch Logs group to which CloudTrail events are delivered.	string	"cloudtrail-multi-region"	no
cloudtrail_iam_role_name	The name of the IAM Role to be used by CloudTrail to delivery logs to CloudWatch Logs group.	string	"CloudTrail-CloudWatch-Delivery-Role"	no
cloudtrail_iam_role_policy_name	The name of the IAM Role Policy to be used by CloudTrail to delivery logs to CloudWatch Logs group.	string	"CloudTrail-CloudWatch-Delivery-Policy"	no
cloudtrail_key_deletion_window_in_days	Duration in days after which the key is deleted after destruction of the resource, must be between 7 and 30 days. Defaults to 30 days.	string	"10"	no
cloudtrail_name	The name of the trail.	string	"cloudtrail-multi-region"	no
cloudtrail_s3_key_prefix	The prefix used when CloudTrail delivers events to the S3 bucket.	string	"cloudtrail"	no
cloudwatch_logs_retention_in_days	Number of days to retain logs for. CIS recommends 365 days. Possible values are: 0, 1, 3, 5, 7, 14, 30, 60, 90, 120, 150, 180, 365, 400, 545, 731, 1827, and 3653. Set to 0 to keep logs indefinitely.	string	"365"	no
config_aggregator_name	The name of the organizational AWS Config Configuration Aggregator.	string	"organization-aggregator"	no
config_aggregator_name_prefix	The prefix of the name for the IAM role attached to the organizational AWS Config Configuration Aggregator.	string	"config-for-organization-role"	no
config_delivery_frequency	The frequency which AWS Config sends a snapshot into the S3 bucket.	string	"One_Hour"	no
config_iam_role_name	The name of the IAM Role which AWS Config will use.	string	"Config-Recorder"	no
config_iam_role_policy_name	The name of the IAM Role Policy which AWS Config will use.	string	"Config-Recorder-Policy"	no
config_s3_bucket_key_prefix	The prefix used when writing AWS Config snapshots into the S3 bucket.	string	"config"	no
config_sns_topic_name	The name of the SNS Topic to be used to notify configuration changes.	string	"ConfigChanges"	no
guardduty_disable_email_notification	Boolean whether an email notification is sent to the accounts.	string	"false"	no
guardduty_finding_publishing_frequency	Specifies the frequency of notifications sent for subsequent finding occurrences.	string	"SIX_HOURS"	no
guardduty_invitation_message	Message for invitation.	string	"This is an automatic invitation message from guardduty-baseline module."	no
manager_iam_role_name	The name of the IAM Manager role.	string	"IAM-Manager"	no
manager_iam_role_policy_name	The name of the IAM Manager role policy.	string	"IAM-Manager-Policy"	no
master_account_id	The ID of the master AWS account to which the current AWS account is associated. Required if account\_type is member.	string	""	no
master_iam_role_name	The name of the IAM Master role.	string	"IAM-Master"	no
master_iam_role_policy_name	The name of the IAM Master role policy.	string	"IAM-Master-Policy"	no
max_password_age	The number of days that an user password is valid.	string	"90"	no
member_accounts	A list of IDs and emails of AWS accounts which associated as member accounts.	object	[]	no
minimum_password_length	Minimum length to require for user passwords.	string	"14"	no
password_reuse_prevention	The number of previous passwords that users are prevented from reusing.	string	"24"	no
region	The AWS region in which global resources are set up.	string	n/a	yes
require_lowercase_characters	Whether to require lowercase characters for user passwords.	string	"true"	no
require_numbers	Whether to require numbers for user passwords.	string	"true"	no
require_symbols	Whether to require symbols for user passwords.	string	"true"	no
require_uppercase_characters	Whether to require uppercase characters for user passwords.	string	"true"	no
support_iam_role_name	The name of the the support role.	string	"IAM-Support"	no
support_iam_role_policy_name	The name of the support role policy.	string	"IAM-Support-Role"	no
support_iam_role_principal_arn	The ARN of the IAM principal element by which the support role could be assumed.	string	n/a	yes
tags	Specifies object tags key and value. This applies to all resources created by this module.	map	{}	no
target_regions	A list of regions to set up with this module.	list	[ "ap-northeast-1", "ap-northeast-2", "ap-south-1", "ap-southeast-1", "ap-southeast-2", "ca-central-1", "eu-central-1", "eu-north-1", "eu-west-1", "eu-west-2", "eu-west-3", "sa-east-1", "us-east-1", "us-east-2", "us-west-1", "us-west-2" ]	no
use_external_audit_log_bucket	A boolean that indicates whether the specific audit log bucket already exists. Create a new S3 bucket if it is set to false.	string	"false"	no
vpc_iam_role_name	The name of the IAM Role which VPC Flow Logs will use.	string	"VPC-Flow-Logs-Publisher"	no
vpc_iam_role_policy_name	The name of the IAM Role Policy which VPC Flow Logs will use.	string	"VPC-Flow-Logs-Publish-Policy"	no
vpc_log_group_name	The name of CloudWatch Logs group to which VPC Flow Logs are delivered.	string	"default-vpc-flow-logs"	no
vpc_log_retention_in_days	Number of days to retain logs for. CIS recommends 365 days. Possible values are: 0, 1, 3, 5, 7, 14, 30, 60, 90, 120, 150, 180, 365, 400, 545, 731, 1827, and 3653. Set to 0 to keep logs indefinitely.	string	"365"	no

Outputs

Name	Description
alarm_sns_topic	The SNS topic to which CloudWatch Alarms will be sent.
audit_bucket	The S3 bucket used for storing audit logs.
cloudtrail	The trail for recording events in all regions.
cloudtrail_kms_key	The KMS key used for encrypting CloudTrail events.
cloudtrail_log_delivery_iam_role	The IAM role used for delivering CloudTrail events to CloudWatch Logs.
cloudtrail_log_group	The CloudWatch Logs log group which stores CloudTrail events.
config_configuration_recorder	The configuration recorder in each region.
config_iam_role	The IAM role used for delivering AWS Config records to CloudWatch Logs.
config_sns_topic	The SNS topic that AWS Config delivers notifications to.
default_network_acl	The default network ACL.
default_route_table	The default route table.
default_security_group	The ID of the default security group.
default_vpc	The default VPC.
guardduty_detector	The GuardDuty detector in each region.
manager_iam_role	The IAM role used for the manager user.
master_iam_role	The IAM role used for the master user.
support_iam_role	The IAM role used for the support user.
vpc_flow_logs_group	The CloudWatch Logs log group which stores VPC Flow Logs in each region.
vpc_flow_logs_iam_role	The IAM role used for delivering VPC Flow Logs to CloudWatch Logs.