Foundational data sources

GuardDuty uses the foundational data sources to detect communication with known malicious domains and IP addresses, and identify potentially anomalous behavior and unauthorized activity. While in transit from these sources to GuardDuty, all of the log data is encrypted. GuardDuty extracts various fields from these logs sources for profiling and anomaly detection, and then discards these logs.

When you enable GuardDuty for the first time in a Region, there is a 30-day free trial that includes threat detection for all the foundational data sources. During this free trial and thereafter, you can monitor the estimated monthly usage on the GuardDuty console usage page, broken down by data source. As a delegated GuardDuty administrator account, you can view the estimated monthly usage cost broken down by the member accounts in your organization that have enabled GuardDuty.

After you enable GuardDuty in your AWS account, it automatically starts to monitor the log sources explained in the following sections. You don't need to enable anything else for GuardDuty to start analyzing and processing these data sources to generate associated security findings.

AWS CloudTrail event logs

AWS CloudTrail provides you with a history of AWS API calls for your account, including API calls made using the AWS Management Console, the AWS SDKs, the command line tools, and certain AWS services. CloudTrail also helps you identify which users and accounts invoked AWS APIs for services that support CloudTrail, the source IP address from where the calls were invoked, and the time at which the calls were invoked. For more information, see What is AWS CloudTrail in AWS CloudTrail User Guide.

GuardDuty also monitors CloudTrail management events. When you enable GuardDuty, it starts consuming CloudTrail management events directly from CloudTrail through an independent and duplicated stream of events and analyzes your CloudTrail event logs. There is no additional charge when GuardDuty accesses the events recorded in CloudTrail.

GuardDuty does not manage your CloudTrail events or affect your existing CloudTrail configurations. Similarly, your CloudTrail configurations don't affect how GuardDuty consumes and processes the event logs. To manage access and retention of your CloudTrail events, use the CloudTrail service console or API. For more information, see Viewing events with CloudTrail event history in AWS CloudTrail User Guide.

How GuardDuty handles AWS CloudTrail global events

For most AWS services, CloudTrail events are recorded in the AWS Region where they are created. For global services such as AWS Identity and Access Management (IAM), AWS Security Token Service (AWS STS), Amazon Simple Storage Service (Amazon S3), Amazon CloudFront, and Amazon Route 53 (Route 53), events are only generated in the Region where they occur but they have a global significance.

When GuardDuty consumes CloudTrail Global service events with security value such as network configurations or user permissions, it replicates those events and processes them in each Region where you have enabled GuardDuty. This behavior helps GuardDuty maintain user and role profiles in each Region, which is vital to detecting anomalous events.

We highly recommend that you enable GuardDuty in all AWS Regions which are enabled for your AWS account. This helps GuardDuty generate findings about unauthorized or unusual activity even in those Regions that you may not be using actively.

AWS CloudTrail management events

Management events are also known as control plane events. These events provide insight into management operations that are performed on resources in your AWS account.

VPC Flow Logs

The VPC Flow Logs feature of Amazon VPC captures information about the IP traffic going to and from network interfaces attached to the Amazon Elastic Compute Cloud (Amazon EC2) instances within your AWS environment.

When you enable GuardDuty, it immediately starts analyzing your VPC flow logs from Amazon EC2 instances within your account. It consumes VPC flow log events directly from the VPC Flow Logs feature through an independent and duplicative stream of flow logs. This process does not affect any of your existing flow logs configuration.

GuardDuty doesn't manage your flow logs or make them accessible in your account. To manage access to and retention of your flow logs, you must configure the VPC Flow Logs feature.

DNS logs

If you use AWS DNS resolvers for your Amazon EC2 instances (the default setting), then GuardDuty can access and process your request and response DNS logs through the internal AWS DNS resolvers. If you use another DNS resolver, such as OpenDNS or GoogleDNS, or if you set up your own DNS resolvers, then GuardDuty cannot access and process data from this data source.

When you enable GuardDuty, it immediately starts analyzing your DNS logs from an independent stream of data. This data stream is separate from the data provided through the Route 53 Resolver query logging feature. Configuration of this feature does not affect GuardDuty analysis.