SIGNAL - Role Assumed by AWS Service

AnalysisType: rule
Filename: role_assumed_by_aws_service.py
RuleID: "Role.Assumed.by.AWS.Service"
DisplayName: "SIGNAL - Role Assumed by AWS Service"
Enabled: false
CreateAlert: false
LogTypes:
    - AWS.CloudTrail
Severity: Info
DedupPeriodMinutes: 60
Threshold: 1
Tests:
    - Name: Role Assumed by AWS Service
      ExpectedResult: true
      Log:
        awsRegion: us-west-2
        eventCategory: Management
        eventID: 1f3d7d49-6637-3304-b959-9be15f20215d
        eventName: AssumeRole
        eventSource: sts.amazonaws.com
        eventTime: "2024-06-02 20:27:12"
        eventType: AwsApiCall
        eventVersion: "1.08"
        managementEvent: true
        readOnly: true
        recipientAccountId: "123456789123"
        requestID: a0dda101-6e27-4f88-8250-f3d475f88b56
        requestParameters:
            roleArn: arn:aws:iam::123456789123:role/my_role_arn
            roleSessionName: awslambda_55_20240602202712548
        resources:
            - accountId: "123456789123"
              arn: arn:aws:iam::123456789123:role/my_role_arn
              type: AWS::IAM::Role
        responseElements:
            credentials:
                accessKeyId: REDACTED
                expiration: Jun 2, 2024, 10:37:12 PM
                sessionToken: REDACTED
        sharedEventID: 95e84e79-100a-40a6-985e-3c9c4b41f622
        sourceIPAddress: lambda.amazonaws.com
        userAgent: lambda.amazonaws.com
        userIdentity:
            invokedBy: lambda.amazonaws.com
            type: AWSService


# ------ paired body: role_assumed_by_aws_service.py ------

def rule(event):
    aws_service = event.deep_get("userIdentity", "type") == "AWSService"
    return all(
        [
            event.get("eventName") == "AssumeRole",
            event.deep_get("requestParameters", "roleArn"),
            aws_service,
        ]
    )