Class: Terrafying::Components::Security::Trail

Inherits:
Terrafying::Context
  • Object
show all
Defined in:
lib/terrafying/components/security/trail.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.bucket_statements(bucket_name) ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 17

def self.bucket_statements(bucket_name)
  [
    {
      Sid: "AWSCloudTrailAclCheck",
      Effect: "Allow",
      Principal: {
        Service: "cloudtrail.amazonaws.com"
      },
      Action: "s3:GetBucketAcl",
      Resource: "arn:aws:s3:::#{bucket_name}"
    },
    {
      Sid: "AWSCloudTrailWrite",
      Effect: "Allow",
      Principal: {
        Service: "cloudtrail.amazonaws.com"
      },
      Action: "s3:PutObject",
      Resource: "arn:aws:s3:::#{bucket_name}/*",
      Condition: {
        StringEquals: {
          "s3:x-amz-acl" => "bucket-owner-full-control"
        }
      }
    }
  ]
end

.create(*args) ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 13

def self.create(*args)
  Trail.new.create(*args)
end

.key_statements ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 45

def self.key_statements
  [
    {
      Sid: "Allow CloudTrail to encrypt logs",
      Effect: "Allow",
      Principal: {"Service": ["cloudtrail.amazonaws.com"]},
      Action: "kms:GenerateDataKey*",
      Resource: "*",
      Condition: {"StringLike": {"kms:EncryptionContext:aws:cloudtrail:arn": "arn:aws:cloudtrail:*:#{aws.}:trail/*"}}
    },
    {
      Sid: "Allow CloudTrail to describe key",
      Effect: "Allow",
      Principal: {"Service": ["cloudtrail.amazonaws.com"]},
      Action: "kms:DescribeKey",
      Resource: "*"
    },
    {
      Sid: "Allow principals in the account to decrypt log files",
      Effect: "Allow",
      Principal: {"AWS": "*"},
      Action: [
        "kms:Decrypt",
        "kms:ReEncryptFrom"
      ],
      Resource: "*",
      Condition: {
        StringEquals: {"kms:CallerAccount": aws.},
        StringLike: {"kms:EncryptionContext:aws:cloudtrail:arn": "arn:aws:cloudtrail:*:#{aws.}:trail/*"}
      }
    },
  ]
end

Instance Method Details

#alert!(name:, pattern:, threshold: 1, topic: @topic) ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 261

def alert!(name:, pattern:, threshold: 1, topic: @topic)

  ident = "cloudwatch-#{@name}-#{name}"

  resource :aws_cloudwatch_log_metric_filter, ident, {
             name: name,
             pattern: pattern,
             log_group_name: @log_group["name"],

             metric_transformation: {
               name: "EventCount",
               namespace: "CloudTrail/#{name}",
               value: "1",
             },
           }

  resource :aws_cloudwatch_metric_alarm, ident, {
             alarm_name: name,
             comparison_operator: "GreaterThanOrEqualToThreshold",
             evaluation_periods: "1",
             metric_name: "EventCount",
             namespace: "CloudTrail/#{name}",
             period: "300",
             statistic: "Sum",
             threshold: "#{threshold}",
             alarm_actions: [ topic ],
           }

end

#basic_selector ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 179

def basic_selector
  {
    event_selector: [
      {
        read_write_type: "All",
        include_management_events: true,

        data_resource: {
          type: "AWS::S3::Object",
          values: ["arn:aws:s3:::"],
        }
      },
      {
        read_write_type: "All",
        include_management_events: true,

        data_resource: {
          type: "AWS::Lambda::Function",
          values: ["arn:aws:lambda"],
        },
      }
    ]
  }
end

#cis_benchmark! ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 291

def cis_benchmark!

  # 3.1	Ensure a log metric filter and alarm exist for unauthorized API calls
  alert!(
    name: "UnauthorizedAPICalls",
    pattern: "{ ($.errorCode = \"*UnauthorizedOperation\") || ($.errorCode = \"AccessDenied*\") }",
  )

  # 3.2	Ensure a log metric filter and alarm exist for Management Console sign-in without MFA
  alert!(
    name: "NoMFAConsoleSignin",
    pattern: "{ ($.eventName = \"ConsoleLogin\") && ($.additionalEventData.MFAUsed != \"Yes\") }",
  )

  # 3.3	Ensure a log metric filter and alarm exist for usage of "root" account
  alert!(
    name: "RootUsage",
    pattern: "{ $.userIdentity.type = \"Root\" && $.userIdentity.invokedBy NOT EXISTS && $.eventType != \"AwsServiceEvent\" }",
  )

  # 3.4	Ensure a log metric filter and alarm exist for IAM policy changes
  alert!(
    name: "IAMChanges",
    pattern: "{($.eventName=DeleteGroupPolicy)||($.eventName=DeleteRolePolicy)||($.eventName=DeleteUserPolicy)||($.eventName=PutGroupPolicy)||($.eventName=PutRolePolicy)||($.eventName=PutUserPolicy)||($.eventName=CreatePolicy)||($.eventName=DeletePolicy)||($.eventName=CreatePolicyVersion)||($.eventName=DeletePolicyVersion)||($.eventName=AttachRolePolicy)||($.eventName=DetachRolePolicy)||($.eventName=AttachUserPolicy)||($.eventName=DetachUserPolicy)||($.eventName=AttachGroupPolicy)||($.eventName=DetachGroupPolicy)}",
  )

  # 3.5	Ensure a log metric filter and alarm exist for CloudTrail configuration changes
  alert!(
    name: "CloudTrailCfgChanges",
    pattern: "{ ($.eventName = CreateTrail) || ($.eventName = UpdateTrail) || ($.eventName = DeleteTrail) || ($.eventName = StartLogging) || ($.eventName = StopLogging) }",
  )

  # 3.6	Ensure a log metric filter and alarm exist for AWS Management Console authentication failures
  alert!(
    name: "ConsoleSigninFailures",
    pattern: "{ ($.eventName = ConsoleLogin) && ($.errorMessage = \"Failed authentication\") }",
  )

  # 3.7	Ensure a log metric filter and alarm exist for disabling or scheduled deletion of customer created CMKs
  alert!(
    name: "DisableOrDeleteCMK",
    pattern: "{ ($.eventSource = kms.amazonaws.com) && (($.eventName = DisableKey) || ($.eventName = ScheduleKeyDeletion)) }",
  )

  # 3.8	Ensure a log metric filter and alarm exist for S3 bucket policy changes
  alert!(
    name: "S3BucketPolicyChanges",
    pattern: "{ ($.eventSource = s3.amazonaws.com) && (($.eventName = PutBucketAcl) || ($.eventName = PutBucketPolicy) || ($.eventName = PutBucketCors) || ($.eventName = PutBucketLifecycle) || ($.eventName = PutBucketReplication) || ($.eventName = DeleteBucketPolicy) || ($.eventName = DeleteBucketCors) || ($.eventName = DeleteBucketLifecycle) || ($.eventName = DeleteBucketReplication)) }",
  )

  # 3.9	Ensure a log metric filter and alarm exist for AWS Config configuration changes
  alert!(
    name: "AWSConfigChanges",
    pattern: "{ ($.eventSource = config.amazonaws.com) && (($.eventName=StopConfigurationRecorder)||($.eventName=DeleteDeliveryChannel)||($.eventName=PutDeliveryChannel)||($.eventName=PutConfigurationRecorder)) }",
  )

  # 3.10	Ensure a log metric filter and alarm exist for security group changes
  alert!(
    name: "SecurityGroupChanges",
    pattern: "{ ($.eventName = AuthorizeSecurityGroupIngress) || ($.eventName = AuthorizeSecurityGroupEgress) || ($.eventName = RevokeSecurityGroupIngress) || ($.eventName = RevokeSecurityGroupEgress) || ($.eventName = CreateSecurityGroup) || ($.eventName = DeleteSecurityGroup)}",
  )

  # 3.11	Ensure a log metric filter and alarm exist for changes to Network Access Control Lists (NACL)
  alert!(
    name: "NACLChanges",
    pattern: "{ ($.eventName = CreateNetworkAcl) || ($.eventName = CreateNetworkAclEntry) || ($.eventName = DeleteNetworkAcl) || ($.eventName = DeleteNetworkAclEntry) || ($.eventName = ReplaceNetworkAclEntry) || ($.eventName = ReplaceNetworkAclAssociation) }",
  )

  # 3.12	Ensure a log metric filter and alarm exist for changes to network gateways
  alert!(
    name: "NetworkGWChanges",
    pattern: "{ ($.eventName = CreateCustomerGateway) || ($.eventName = DeleteCustomerGateway) || ($.eventName = AttachInternetGateway) || ($.eventName = CreateInternetGateway) || ($.eventName = DeleteInternetGateway) || ($.eventName = DetachInternetGateway) }",
  )

  # 3.13	Ensure a log metric filter and alarm exist for route table changes
  alert!(
    name: "RouteTableChanges",
    pattern: "{ ($.eventName = CreateRoute) || ($.eventName = CreateRouteTable) || ($.eventName = ReplaceRoute) || ($.eventName = ReplaceRouteTableAssociation) || ($.eventName = DeleteRouteTable) || ($.eventName = DeleteRoute) || ($.eventName = DisassociateRouteTable) }",
  )

  # 3.14	Ensure a log metric filter and alarm exist for VPC changes
  alert!(
    name: "VPCChanges",
    pattern: "{ ($.eventName = CreateVpc) || ($.eventName = DeleteVpc) || ($.eventName = ModifyVpcAttribute) || ($.eventName = AcceptVpcPeeringConnection) || ($.eventName = CreateVpcPeeringConnection) || ($.eventName = DeleteVpcPeeringConnection) || ($.eventName = RejectVpcPeeringConnection) || ($.eventName = AttachClassicLinkVpc) || ($.eventName = DetachClassicLinkVpc) || ($.eventName = DisableVpcClassicLink) || ($.eventName = EnableVpcClassicLink) }",
  )

end

#create(name, store:, topic:, include_all_regions: true, include_all_organisation: true, ignore_buckets: []) ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 79

def create(
      name,
      store:,
      topic:,
      include_all_regions: true,
      include_all_organisation: true,
      ignore_buckets: []
    )

  @name = name
  @topic = topic

  @log_group = resource :aws_cloudwatch_log_group, "cloudtrail-#{name}", {
                          name: "cloudtrail-#{name}",
                        }

  log_role = resource :aws_iam_role, "cloudtrail-#{name}-logs", {
                        name: "cloudtrail-#{name}-logs",
                        assume_role_policy: {
                          Version: "2012-10-17",
                          Statement: [
                            {
                              Sid: "",
                              Effect: "Allow",
                              Principal: {
                                Service: "cloudtrail.amazonaws.com"
                              },
                              Action: "sts:AssumeRole",
                            },
                          ],
                        }.to_json,
                      }

  log_role_policy = resource :aws_iam_policy, "cloudtrail-#{name}-logs", {
                               name: "cloudtrail-#{name}-logs",
                               policy: {
                                 Version: "2012-10-17",
                                 Statement: [
                                   {
                                     Sid: "AWSCloudTrailCreateLogStream2014110",
                                     Effect: "Allow",
                                     Action: [
                                       "logs:CreateLogStream"
                                     ],
                                     Resource: [
                                       "#{@log_group["arn"]}:*",
                                     ]
                                   },
                                   {
                                     Sid: "AWSCloudTrailPutLogEvents20141101",
                                     Effect: "Allow",
                                     Action: [
                                       "logs:PutLogEvents"
                                     ],
                                     Resource: [
                                       "#{@log_group["arn"]}:*",
                                     ]
                                   }
                                 ]
                               }.to_json
                             }

  resource :aws_iam_role_policy_attachment, "cloudtrail-#{name}-logs", {
             role: log_role["name"],
             policy_arn: log_role_policy["arn"],
           }

  data_event_selectors = event_selector(ignore_buckets)

  resource :aws_cloudtrail, "#{name}", {
             name: "#{name}",
             s3_bucket_name: store.name,
             s3_key_prefix: "cloudtrail",
             include_global_service_events: true,
             is_multi_region_trail: include_all_regions,
             is_organization_trail: include_all_organisation,
             enable_log_file_validation: true,
             kms_key_id: store.key_arn,

             cloud_watch_logs_group_arn: "#{@log_group["arn"]}:*",
             cloud_watch_logs_role_arn: log_role["arn"],

           }.deep_merge(data_event_selectors)
  self
end

#event_selector(buckets) ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 165

def event_selector(buckets)
  buckets = Array(buckets)

  return basic_selector if buckets.empty?

  {
    advanced_event_selector: [
      ignore_buckets_selectors(buckets),
      management_events_selector,
      lambda_events
    ]
  }
end

#ignore_buckets_selectors(buckets) ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 204

def ignore_buckets_selectors(buckets)
  ignore_bucket_arns = Array(buckets).map { |bucket|
    data_name = Digest::SHA256.hexdigest("#{@name}-#{bucket}")[0..16]
    arn = data(:aws_s3_bucket, "ct-ignore-#{data_name}", bucket: bucket)['arn']
    "#{arn}/"
  }

  {
    name: 'Log all S3 buckets objects events except these',

    field_selector: [
      {
        field: 'eventCategory',
        equals: ['Data']
      },
      {
        field: 'resources.type',
        equals: ['AWS::S3::Object']
      },
      {
        field: 'resources.ARN',
        not_starts_with: ignore_bucket_arns
      }
    ],
  }
end

#lambda_events ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 244

def lambda_events
  {
    name: 'Log Lambda data events',

    field_selector: [
      {
        field: 'eventCategory',
        equals: ['Data']
      },
      {
        field: 'resources.type',
        equals: ['AWS::Lambda::Function']
      }
    ]
  }
end

#management_events_selector ⇒ Object 



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# File 'lib/terrafying/components/security/trail.rb', line 231

def management_events_selector
  {
    name: 'Log readOnly and writeOnly management events',

    field_selector: [
      {
        field: "eventCategory",
        equals: ["Management"]
      }
    ]
  }
end