SIEM on Amazon OpenSearch Service

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SIEM on Amazon OpenSearch Service is a solution for collecting multiple types of logs from multiple AWS accounts, correlating and visualizing the logs to help investigate security incidents. Deployment is easily done with the help of AWS CloudFormation or AWS Cloud Development Kit (AWS CDK), taking only about 30 minutes to complete. As soon as AWS services logs are put into a specified Amazon Simple Storage Service (Amazon S3) bucket, a purpose-built AWS Lambda function automatically loads those logs into SIEM on OpenSearch Service, enabling you to view visualized logs in the dashboard and correlate multiple logs to investigate security incidents.

Jump to | Configuring AWS Services(Log Sources) | Changing Configurations of SIEM on OpenSearch Service | Advanced Deployment | OpenSearch Serverless | Dashboard | AWS Control Tower Integration | Amazon Security Lake Integration | Supported Log Types | FAQ | Changelog |

Architecture

AWS Control Tower Integration

Amazon Security Lake Integration

Supported Log Types

SIEM on OpenSearch Service can load and correlate the following log types.

	AWS Service	Log
Security, Identity, & Compliance	AWS CloudHSM	HSM audit logs
Security, Identity, & Compliance	Amazon GuardDuty	GuardDuty findings
Security, Identity, & Compliance	Amazon Inspector	Inspector findings
Security, Identity, & Compliance	AWS Directory Service	Microsoft AD
Security, Identity, & Compliance	AWS WAF	AWS WAF Web ACL traffic information AWS WAF Classic Web ACL traffic information
Security, Identity, & Compliance	AWS Security Hub	Security Hub findings GuardDuty findings Amazon Macie findings Amazon Inspector findings AWS IAM Access Analyzer findings
Security, Identity, & Compliance	AWS Network Firewall	Flow logs Alert logs
Management & Governance	AWS CloudTrail	CloudTrail Log Event CloudTrail Insight Event
Management & Governance	AWS Config	Configuration History Configuration Snapshot Config Rules
Management & Governance	AWS Trusted Advisor	Trusted Advisor Check Result
Networking & Content Delivery	Amazon CloudFront	Standard access log Real-time log
Networking & Content Delivery	Amazon Route 53 Resolver	VPC DNS query log
Networking & Content Delivery	Amazon Virtual Private Cloud (Amazon VPC)	VPC Flow Logs (Version5) Text / Parquet Format
Networking & Content Delivery	AWS Transit Gateway	VPC Flow Logs (Version6) Text / Parquet Format
Networking & Content Delivery	Elastic Load Balancing	Application Load Balancer access logs Network Load Balancer access logs Classic Load Balancer access logs
Networking & Content Delivery	AWS Client VPN	connection log
Storage	Amazon FSx for Windows File Server	audit log
Storage	Amazon Simple Storage Service (Amazon S3)	access log
Database	Amazon Relational Database Service (Amazon RDS)	Amazon Aurora(MySQL) Amazon Aurora(PostgreSQL) Amazon RDS for MariaDB Amazon RDS for MySQL Amazon RDS for PostgreSQL
Database	Amazon ElastiCache	ElastiCache for Redis SLOWLOG
Analytics	Amazon OpenSearch Service	Audit logs
Analytics	Amazon Managed Streaming for Apache Kafka (Amazon MSK)	Broker log
Compute	Linux OS via CloudWatch Logs	/var/log/messages /var/log/secure
Compute	Windows Server 2012/2016/2019 via CloudWatch Logs	System event log Security event log
Containers	Amazon Elastic Container Service (Amazon ECS) via FireLens	Framework only
End User Computing	Amazon WorkSpaces	Event log Inventory
Open Source Software	Apache Web Server	access log(CLF, combined, combinedio with XFF) error log
Open Source Software	NGINX Web Server	access log(combined with XFF) error log

Experimental Support: We may change field type, normalization and something in the future.

Supported logs are normalized in accordance with the Elastic Common Schema. Click here to see the correspondence table of the original and normalized field names for the logs.

Contribution

Product/Service	Pull Request	Doc	Contributor
TrendMicro Deep Security	#27	README	@EijiSugiura
Okta audit log	#168	README	@yopiyama

Dashboard

See this

Getting Started

In this tutorial, you will create a publicly accessible SIEM on OpenSearch Service domain using a CloudFormation template. See Advanced Deployment if you need to deploy it within an Amazon VPC or need to customize it.

You can add country information as well as latitude/longitude location information to each IP address. To get location information, SIEM on OpenSearch Service downloads and uses GeoLite2 Free by MaxMind. If you want to add location information, get your free license from MaxMind.

Threat information can be enriched based on IP addresses and domain names (EXPERIMANTAL). Threat information sources include your own IoCs (Indicators of compromise) in TXT and STIX 2.x formats, Tor Project, Abuse.ch Feodo Tracker, AlienVault OTX. If there are many IoCs, the processing time of Lambda will increase, so please select IoCs carefully. If you want to use the IoC on AlienVault OTX, please get your API key at AlienVault OTX. See Threat Information Enrichment by IoC for more details.

Note: The CloudFormation template will deploy OpenSearch Service with a t3.medium.search instance. It's not the AWS Free Tier. Change it to an instance type that can deliver higher performance than t3 when using SIEM in the production environment as it requires higher processing power when aggregating many logs. Use the AWS Management Console to change the instance type, extend the volume, or use UltraWarm. This is because the CloudFormation template for SIEM on OpenSearch Service is designed for the initial deployment purpose only, and cannot be used for management purposes like changing/deleting nodes.

1. Quick Start

Choose a region where you want to deploy SIEM on OpenSearch Service from the following. If there is no region below, please check CloudFormation Template For All Regions.

Region	CloudFormation	Template URL
US East (N. Virginia) us-east-1		https://aes-siem-us-east-1.s3.amazonaws.com/siem-on-amazon-opensearch-service.template
US West (Oregon) us-west-2		https://aes-siem-us-west-2.s3.amazonaws.com/siem-on-amazon-opensearch-service.template
Asia Pacific (Tokyo) ap-northeast-1		https://aes-siem-ap-northeast-1.s3.amazonaws.com/siem-on-amazon-opensearch-service.template
Asia Pacific (Singapore) ap-southeast-1		https://aes-siem-ap-southeast-1.s3.amazonaws.com/siem-on-amazon-opensearch-service.template
Europe (Frankfurt) eu-central-1		https://aes-siem-eu-central-1.s3.amazonaws.com/siem-on-amazon-opensearch-service.template
Europe (London) eu-west-2		https://aes-siem-eu-west-2.s3.amazonaws.com/siem-on-amazon-opensearch-service.template

Or you can create your own template by the steps.

2. Configuring OpenSearch Dashboards

It will take about 30 mins for the deployment of SIEM on OpenSearch Service to complete. You can then continue to configure OpenSearch Dashboards.

1. Navigate to the AWS CloudFormation console, choose the stack that you've just created, and then choose "Outputs" from the tab menu at the top right. You can find your username, password, and URL for OpenSearch Dashboards. Log into OpenSearch Dashboards using the credentials.
2. When you login for the first time, [Select your tenant] is displayed. Select [Global]. You can use the prepared dashboard etc.
3. You can also select [Private] instead of [Global] in [Select your tenant] and customize configuration and dashboard etc. for each user. The following is the procedure for each user. If you select Global, you do not need to set it.
   1. To import OpenSearch Dashboards' configuration files such as dashboard, download saved_objects.zip. Then unzip the file.
   2. Navigate to the OpenSearch Dashboards console. Click on "Stack Management" in the left pane, then choose "Saved Objects" --> "Import" --> "Import". Choose dashboard.ndjson which is contained in the unzipped folder. Then log out and log in again so that the imported configurations take effect.

3. Loading logs into OpenSearch Service

All you need to do to load logs into SIEM on OpenSearch Service is PUT logs to the S3 Bucket named aes-siem-<YOUR_AWS_ACCOUNT>-log. Then the logs will be automatically loaded into SIEM on OpenSearch Service. See this for detailed instructions on how to output AWS services logs to the S3 bucket.

Workshop

We have published the workshop, SIEM on Amazon OpenSearch Service Workshop. In this workshop, we will build the SIEM, ingest AWS resource logs, learn OpenSearch Dashboards, investigate security incident, create dashboard, configure alerts and ingest logs of Apache HTTPD server.

Updating SIEM

If you want to update "SIEM on OpenSearch Service" to the latest version, upgrade the OpenSearch / Elasticsearch domain and then update it in the same way as you did for the initial setup (using CloudFormation or AWS CDK.) You can view the changelog of SIEM here.

Note: When you update SIEM, Global tenant settings, dashboards, etc. will be overwritten automatically. The configuration files and dashboards used before the update will be backed up to aes-siem-[AWS_Account]-snapshot/saved_objects/ in the S3 bucket, so restore them manually if you want to restore the original settings.

Note: S3 bucket policy, KMS key policy, IAM policy, etc. are automatically generated by CDK/CloudFormation. Manual modification is not recommended, but if you have modified it, it will be overwritten, so please back up each and update the difference after updating. Or when updating CDK/CloudFormation, keep the current bucket policy by setting the parameter LogBucketPolicyUpdate to keep

Upgrading the OpenSearch Service domain

Upgrade the domain to OpenSearch 1.0 - 2.11 or Elasticsearch version 7.10. Some Dashboards assume OpenSearch Service 1.3 or higher. The recommended version is OpenSearch Service 2.11 with "Enable compatibility mode":

1. Navigate to the OpenSearch Service console
2. Choose domain: [aes-siem]
3. Choose [Actions] icon, and choose [Upgrade domain] from the drop-down menu
4. For "Version to upgrade to", choose [OpenSearch 2.11] (Recommended), [OpenSearch 1.0 - 2.9], or [Elasticsearch 7.10]
5. Choose "Enable compatibility mode" (Recommended)
6. Then choose [Submit]

If you completed the initial setup using CloudFormation, move on to the next step. If you completed the initial setup using the AWS CDK, see
"Updating SIEM with the AWS CDK" section in Advanced Deployment.

Updating the CloudFormation stack

You can update the CloudFormation stack by specifying the CloudFormation template below:

https://aes-siem-<REGION>.s3.amazonaws.com/siem-on-amazon-opensearch-service.template

1. Navigate to the CloudFormation console
2. Choose stack [aes-siem]
3. Choose [Update] at the right top on the screen
4. In Update stack, choose the following:
   • Prepare template: [Replace current template]
   • Template source: [Amazon S3 URL]
   • Amazon S3 URL:
   • Choose [Next]
5. Leave all the other settings as default, and continue to click Next to complete.

Updating is now complete.

Changing Configurations

Changing the OpenSearch Service domain resources after deployment

If you want to make changes to the OpenSearch Service domain itself such as changing the access policy of OpenSearch Service, changing the instance type, changing the Availability Zone or adding a new one, or changing to UltraWarm, perform the change from the OpenSearch Service console of AWS Management Console.

Managing the index and customizing SIEM

SIEM on OpenSearch Service saves logs in the index and rotates it once a month. If you want to change this interval or load logs from non-AWS services, see this.

Near-real-time logs loading from non-SIEM-managed S3 buckets

If you have an S3 bucket in the same account and region as the SIEM, you can load logs into OpenSearch Service. Please refer Near-real-time loading from other S3 buckets for the setting method.

Loading stored logs through batch processing

You can execute es-loader, which is a python script, in the local environment to load past logs stored in the S3 bucket into SIEM on OpenSearch Service. See Loading past data stored in the S3 bucket for details.

Throttling of es-loader in an emergency

To avoid unnecessary invocation of es-loader, throttle es-loader under the following conditions

• If total free space for the OpenSearch Service cluster remains less than 200MB for 30 minutes and aes-siem-TotalFreeStorageSpaceRemainsLowAlarm is triggered.
  • The OpenSearch cluster is running out of storage space. More free space is needed for recovery. To learn more, see Lack of available storage space.

If you want to resume loading logs, set the reserved concurrency of the Lambda function aes-siem-es-loader back to 10 from the AWS Management Console or AWS CLI. You can also load messages from the dead-letter queue (aes-siem-dlq) by referring to Loading data from SQS Dead Letter Queue.

AWS resources created by the CloudFormation template

Below is the list of AWS resources created by the CloudFormation template. AWS Identity and Access Management (IAM) resources can be found from the AWS Management Console.

AWS Resource	Resource Name	Purpose
OpenSearch Service	aes-siem	SIEM itself
S3 bucket	aes-siem-[AWS_Account]-log	For collecting logs
S3 bucket	aes-siem-[AWS_Account]-snapshot	For capturing manual snapshots of OpenSearch Service
S3 bucket	aes-siem-[AWS_Account]-geo	For storing downloaded GeoIPs
Step Functions	aes-siem-ioc-state-machine	For downloading IoC and creating database
Lambda function	aes-siem-aws-api-caller	CDK/CloudFormation custom resource to make an AWS API call
Lambda function	aes-siem-ioc-plan	For creating map to download IoC
Lambda function	aes-siem-ioc-createdb	For downloading IoC
Lambda function	aes-siem-ioc-download	For creating IoC Database
Lambda function	aes-siem-geoip-downloader	For downloading GeoIPs
Lambda function	aes-siem-es-loader	For normalizing logs and loading them into OpenSearch Service
Lambda function	aes-siem-es-loader-stopper	For throttling es-loader in case of emergency
Lambda function	aes-siem-deploy-aes	For creating the OpenSearch Service domain
Lambda function	aes-siem-configure-aes	For configuring OpenSearch Service
Lambda function	aes-siem-index-metrics-exporter	For OpenSearch Service index metrics
Lambda function	aes-siem-BucketNotificationsHandler	For configuring invent notification for the S3 bucket that stores logs
Lambda function	aes-siem-add-pandas-layer	For adding aws_sdk_pandas as Lambda layer to es-loader
AWS Key Management Service (AWS KMS) KMS key & Alias	aes-siem-key	For encrypting logs
SSM Parameter Store	/siem/bucketpolicy/log/policy1-8	Temporarily used when keeping the s3 log Bucket Policy
Amazon SQS Queue	aes-siem-sqs-splitted-logs	A log is split into multiple parts if it has many lines to process. This is the queue to coordinate it
Amazon SQS Queue	aes-siem-dlq	A dead-letter queue used when loading logs into OpenSearch Service fails
CloudWatch alarms	aes-siem-TotalFreeStorageSpaceRemainsLowAlarm	Triggered when total free space for the OpenSearch Service cluster remains less than 200MB for 30 minutes
CloudWatch dashboards	SIEM	Dashboard of resource information used by SIEM on OpenSearch Service
EventBridge events	aes-siem-EventBridgeRuleStepFunctionsIoc	For executing aes-siem-ioc-state-machine regularly
EventBridge events	aes-siem-EventBridgeRuleLambdaGeoipDownloader	For executing aes-siem-geoip-downloader every 12 hours
EventBridge events	aes-siem-EventBridgeRuleLambdaMetricsExporter	For executing aes-siem-geoip-downloader every 1 hour
EventBridge events	aes-siem-EsLoaderStopperRule	For passing alarm events to es-loader-stopper
Amazon SNS Topic	aes-siem-alert	This is selected as the destination for alerting in OpenSearch Service
Amazon SNS Subscription	inputed email	This is the email address where alerts are sent

Cleanup

1. Navigate to the CloudFormation console and delete stack: aes-siem
2. Delete the following AWS resources manually:
   • OpenSearch Service domain: aes-siem
   • Amazon S3 bucket: aes-siem-[AWS_Account]-log
   • Amazon S3 bucket: aes-siem-[AWS_Account]-snapshot
   • Amazon S3 bucket: aes-siem-[AWS_Account]-geo
   • AWS KMS customer-managed key: aes-siem-key
     • Please delete this with care. After deleting this customer-managed key, you will no longer be able to read logs if they are encrypted using this key.
3. If you deployed SIEM on OpenSearch Service within an Amazon VPC, delete the following AWS resources as well:
   • Amazon VPC: aes-siem/VpcAesSiem (if you created a new VPC)
   • SecurityGroup: aes-siem-vpc-sg

Note If you want to redeploy SIEM on OpenSearch Service right after deleting it, you need to delete the key alias using the AWS CLI commands below. Otherwise, redeployment will fail as the KMS key alias still remains:

export AWS_DEFAULT_REGION=<AWS_REGION>
aws kms delete-alias --alias-name  "alias/aes-siem-key"

Security

See CONTRIBUTING for more information.

License

This library is licensed under the MIT-0 License. See the LICENSE file.

This product uses GeoLite2 data created by MaxMind and licensed under CC BY-SA 4.0, available from https://www.maxmind.com.

This product uses Tor exit list created by The Tor Project, Inc and licensed under CC BY 3.0 US, available from https://www.torproject.org