AWS Security Blog
How US federal agencies can use AWS to improve logging and log retention
September 9, 2021: Amazon Elasticsearch Service has been renamed to Amazon OpenSearch Service. See details.
This post is part of a series about how Amazon Web Services (AWS) can help your US federal agency meet the requirements of the President’s Executive Order on Improving the Nation’s Cybersecurity. You will learn how you can use AWS information security practices to help meet the requirement to improve logging and log retention practices in your AWS environment.
Improving the security and operational readiness of applications relies on improving the observability of the applications and the infrastructure on which they operate. For our customers, this translates to questions of how to gather the right telemetry data, how to securely store it over its lifecycle, and how to analyze the data in order to make it actionable. These questions take on more importance as our federal customers seek to improve their collection and management of log data in all their IT environments, including their AWS environments, as mandated by the executive order.
Given the interest in the technologies used to support logging and log retention, we’d like to share our perspective. This starts with an overview of logging concepts in AWS, including log storage and management, and then proceeds to how to gain actionable insights from that logging data. This post will address how to improve logging and log retention practices consistent with the Security and Operational Excellence pillars of the AWS Well-Architected Framework.
Log actions and activity within your AWS account
AWS provides you with extensive logging capabilities to provide visibility into actions and activity within your AWS account. A security best practice is to establish a wide range of detection mechanisms across all of your AWS accounts. Starting with services such as AWS CloudTrail, AWS Config, Amazon CloudWatch, Amazon GuardDuty, and AWS Security Hub provides a foundation upon which you can base detective controls, remediation actions, and forensics data to support incident response. Here is more detail on how these services can help you gain more security insights into your AWS workloads:
- AWS CloudTrail provides event history for all of your AWS account activity, including API-level actions taken through the AWS Management Console, AWS SDKs, command line tools, and other AWS services. You can use CloudTrail to identify who or what took which action, what resources were acted upon, when the event occurred, and other details. If your agency uses AWS Organizations, you can automate this process for all of the accounts in the organization.
- CloudTrail logs can be delivered from all of your accounts into a centralized account. This places all logs in a tightly controlled, central location, making it easier to both protect them as well as to store and analyze them. As with AWS CloudTrail, you can automate this process for all of the accounts in the organization using AWS Organizations. CloudTrail can also be configured to emit metrical data into the CloudWatch monitoring service, giving near real-time insights into the usage of various services.
- CloudTrail log file integrity validation produces and cyptographically signs a digest file that contains references and hashes for every CloudTrail file that was delivered in that hour. This makes it computationally infeasible to modify, delete or forge CloudTrail log files without detection. Validated log files are invaluable in security and forensic investigations. For example, a validated log file enables you to assert positively that the log file itself has not changed, or that particular user credentials performed specific API activity.
- AWS Config monitors and records your AWS resource configurations and allows you to automate the evaluation of recorded configurations against desired configurations. For example, you can use AWS Config to verify that resources are encrypted, multi-factor authentication (MFA) is enabled, and logging is turned on, and you can use AWS Config rules to identify noncompliant resources. Additionally, you can review changes in configurations and relationships between AWS resources and dive into detailed resource configuration histories, helping you to determine when compliance status changed and the reason for the change.
- Amazon GuardDuty is a threat detection service that continuously monitors for malicious activity and unauthorized behavior to protect your AWS accounts and workloads. Amazon GuardDuty analyzes and processes the following data sources: VPC Flow Logs, AWS CloudTrail management event logs, CloudTrail Amazon Simple Storage Service (Amazon S3) data event logs, and DNS logs. It uses threat intelligence feeds, such as lists of malicious IP addresses and domains, and machine learning to identify potential threats within your AWS environment.
- AWS Security Hub provides a single place that aggregates, organizes, and prioritizes your security alerts, or findings, from multiple AWS services and optional third-party products to give you a comprehensive view of security alerts and compliance status.
You should be aware that most AWS services do not charge you for enabling logging (for example, AWS WAF) but the storage of logs will incur ongoing costs. Always consult the AWS service’s pricing page to understand cost impacts. Related services such as Amazon Kinesis Data Firehose (used to stream data to storage services), and Amazon Simple Storage Service (Amazon S3), used to store log data, will incur charges.
Turn on service-specific logging as desired
After you have the foundational logging services enabled and configured, next turn your attention to service-specific logging. Many AWS services produce service-specific logs that include additional information. These services can be configured to record and send out information that is necessary to understand their internal state, including application, workload, user activity, dependency, and transaction telemetry. Here’s a sampling of key services with service-specific logging features:
- Amazon CloudWatch provides you with data and actionable insights to monitor your applications, respond to system-wide performance changes, optimize resource utilization, and get a unified view of operational health. CloudWatch collects monitoring and operational data in the form of logs, metrics, and events, providing you with a unified view of AWS resources, applications, and services that run on AWS and on-premises servers. You can gain additional operational insights from your AWS compute instances (Amazon Elastic Compute Cloud, or EC2) as well as on-premises servers using the CloudWatch agent. Additionally, you can use CloudWatch to detect anomalous behavior in your environments, set alarms, visualize logs and metrics side by side, take automated actions, troubleshoot issues, and discover insights to keep your applications running smoothly.
- Amazon CloudWatch Logs is a component of Amazon CloudWatch which you can use to monitor, store, and access your log files from Amazon Elastic Compute Cloud (Amazon EC2) instances, AWS CloudTrail, Route 53, and other sources. CloudWatch Logs enables you to centralize the logs from all of your systems, applications, and AWS services that you use, in a single, highly scalable service. You can then easily view them, search them for specific error codes or patterns, filter them based on specific fields, or archive them securely for future analysis. CloudWatch Logs enables you to see all of your logs, regardless of their source, as a single and consistent flow of events ordered by time, and you can query them and sort them based on other dimensions, group them by specific fields, create custom computations with a powerful query language, and visualize log data in dashboards.
- Traffic Mirroring allows you to achieve full packet capture (as well as filtered subsets) of network traffic from an elastic network interface of EC2 instances inside your VPC. You can then send the captured traffic to out-of-band security and monitoring appliances for content inspection, threat monitoring, and troubleshooting.
- The Elastic Load Balancing service provides access logs that capture detailed information about requests that are sent to your load balancer. Each log contains information such as the time the request was received, the client’s IP address, latencies, request paths, and server responses. The specific information logged varies by load balancer type:
- Amazon S3 access logs record the S3 bucket and account that are being accessed, the API action, and requester information.
- AWS Web Application Firewall (WAF) logs record web requests that are processed by AWS WAF, and indicate whether the requests matched AWS WAF rules and what actions, if any, were taken. These logs are delivered to Amazon S3 by using Amazon Kinesis Data Firehose.
- Amazon Relational Database Service (Amazon RDS) log files can be downloaded or published to Amazon CloudWatch Logs. Log settings are specific to each database engine. Agencies use these settings to apply their desired logging configurations and chose which events are logged. Amazon Aurora and Amazon RDS for Oracle also support a real-time logging feature called “database activity streams” which provides even more detail, and cannot be accessed or modified by database administrators.
- Amazon Route 53 provides options for logging for both public DNS query requests as well as Route53 Resolver DNS queries:
- Route 53 Resolver DNS query logs record DNS queries and responses that originate from your VPC, that use an inbound Resolver endpoint, that use an outbound Resolver endpoint, or that use a Route 53 Resolver DNS Firewall.
- Route 53 DNS public query logs record queries to Route 53 for domains you have hosted with AWS, including the domain or subdomain that was requested; the date and time of the request; the DNS record type; the Route 53 edge location that responded to the DNS query; and the DNS response code.
- Amazon Elastic Compute Cloud (Amazon EC2) instances can use the unified CloudWatch agent to collect logs and metrics from Linux, macOS, and Windows EC2 instances and publish them to the Amazon CloudWatch service.
- Elastic Beanstalk logs can be streamed to CloudWatch Logs. You can also use the AWS Management Console to request the last 100 log entries from the web and application servers, or request a bundle of all log files that is uploaded to Amazon S3 as a ZIP file.
- Amazon CloudFront logs record user requests for content that is cached by CloudFront.
Store and analyze log data
Now that you’ve enabled foundational and service-specific logging in your AWS accounts, that data needs to be persisted and managed throughout its lifecycle. AWS offers a variety of solutions and services to consolidate your log data and store it, secure access to it, and perform analytics.
Store log data
The primary service for storing all of this logging data is Amazon S3. Amazon S3 is ideal for this role, because it’s a highly scalable, highly resilient object storage service. AWS provides a rich set of multi-layered capabilities to secure log data that is stored in Amazon S3, including encrypting objects (log records), preventing deletion (the S3 Object Lock feature), and using lifecycle policies to transition data to lower-cost storage over time (for example, to S3 Glacier). Access to data in Amazon S3 can also be restricted through AWS Identity and Access Management (IAM) policies, AWS Organizations service control policies (SCPs), S3 bucket policies, Amazon S3 Access Points, and AWS PrivateLink interfaces. While S3 is particularly easy to use with other AWS services given its various integrations, many customers also centralize their storage and analysis of their on-premises log data, or log data from other cloud environments, on AWS using S3 and the analytic features described below.
If your AWS accounts are organized in a multi-account architecture, you can make use of the AWS Centralized Logging solution. This solution enables organizations to collect, analyze, and display CloudWatch Logs data in a single dashboard. AWS services generate log data, such as audit logs for access, configuration changes, and billing events. In addition, web servers, applications, and operating systems all generate log files in various formats. This solution uses the Amazon Elasticsearch Service (Amazon ES) and Kibana to deploy a centralized logging solution that provides a unified view of all the log events. In combination with other AWS-managed services, this solution provides you with a turnkey environment to begin logging and analyzing your AWS environment and applications.
You can also make use of services such as Amazon Kinesis Data Firehose, which you can use to transport log information to S3, Amazon ES, or any third-party service that is provided with an HTTP endpoint, such as Datadog, New Relic, or Splunk.
Finally, you can use Amazon EventBridge to route and integrate event data between AWS services and to third-party solutions such as software as a service (SaaS) providers or help desk ticketing systems. EventBridge is a serverless event bus service that allows you to connect your applications with data from a variety of sources. EventBridge delivers a stream of real-time data from your own applications, SaaS applications, and AWS services, and then routes that data to targets such as AWS Lambda.
Analyze log data and respond to incidents
As the final step in managing your log data, you can use AWS services such as Amazon Detective, Amazon ES, CloudWatch Logs Insights, and Amazon Athena to analyze your log data and gain operational insights.
- Amazon Detective makes it easy to analyze, investigate, and quickly identify the root cause of security findings or suspicious activities. Detective automatically collects log data from your AWS resources. It then uses machine learning, statistical analysis, and graph theory to help you visualize and conduct faster and more efficient security investigations.
- Incident Manager is a component of AWS Systems Manger which enables you to automatically take action when a critical issue is detected by an Amazon CloudWatch alarm or Amazon Eventbridge event. Incident Manager executes pre-configured response plans to engage responders via SMS and phone calls, enable chat commands and notifications using AWS Chatbot, and execute AWS Systems Manager Automation runbooks. The Incident Manager console integrates with AWS Systems Manager OpsCenter to help you track incidents and post-incident action items from a central place that also synchronizes with popular third-party incident management tools such as Jira Service Desk and ServiceNow.
- Amazon Elasticsearch Service (Amazon ES) is a fully managed service that collects, indexes, and unifies logs and metrics across your environment to give you unprecedented visibility into your applications and infrastructure. With Amazon ES, you get the scalability, flexibility, and security you need for the most demanding log analytics workloads. You can configure a CloudWatch Logs log group to stream data it receives to your Amazon ES cluster in near real time through a CloudWatch Logs subscription.
- CloudWatch Logs Insights enables you to interactively search and analyze your log data in CloudWatch Logs.
- Amazon Athena is an interactive query service that you can use to analyze data in Amazon S3 by using standard SQL. Athena is serverless, so there is no infrastructure to manage, and you pay only for the queries that you run.
As called out in the executive order, information from network and systems logs is invaluable for both investigation and remediation services. AWS provides a broad set of services to collect an unprecedented amount of data at very low cost, optionally store it for long periods of time in tiered storage, and analyze that telemetry information from your cloud-based workloads. These insights will help you improve your organization’s security posture and operational readiness and, as a result, improve your organization’s ability to deliver on its mission.
To learn more about how AWS can help you meet the requirements of the executive order, see the other posts in this series:
- How AWS can help your US federal agency meet the executive order on improving the nation’s cybersecurity
- How US federal agencies can authenticate to AWS with multi-factor authentication
- How US federal agencies can use AWS to encrypt data at rest and in transit
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