# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   guardduty_s3_protection_enabled_check
# 
# Description:
#   This control checks whether Amazon S3 protection is enabled on an Amazon GuardDuty detector.
# 
# Reports on:
#   AWS::GuardDuty::Detector
# 
# Evaluates:
#   AWS CloudFormation, AWS CloudFormation hook
# 
# Rule Parameters:
#   None
# 
# Scenarios:
#   Scenario: 1
#      Given: The input document is an AWS CloudFormation or CloudFormation hook document
#        And: The input document does not contain any Amazon GuardDuty detector resources
#       Then: SKIP
#   Scenario: 2
#      Given: The input document is an AWS CloudFormation or CloudFormation hook document
#        And: The input document contains a GuardDuty detector resource
#        And: 'Enable' has not been specified or specified with value is bool(false)
#       Then: FAIL
#   Scenario: 3
#      Given: The input document is an AWS CloudFormation or CloudFormation hook document
#        And: The input document contains a GuardDuty detector resource
#        And: 'Enable' is specified with a value of bool(true)
#        And: 'DataSources.S3Logs' has not been specified
#       Then: FAIL
#   Scenario: 4
#      Given: The input document is an AWS CloudFormation or CloudFormation hook document
#        And: The input document contains a GuardDuty detector resource
#        And: 'Enable' is specified and value is bool(true)
#        And: 'DataSources.S3Logs' has been specified
#        And: 'Enable' has not been specified within 'S3Logs' or has been specified with a value of bool(false)
#       Then: FAIL
#   Scenario: 5
#      Given: The input document is an AWS CloudFormation or CloudFormation hook document
#        And: The input document contains a GuardDuty detector resource
#        And: 'Enable' is specified and value is bool(true)
#        And: 'DataSources.S3Logs' has been specified
#        And: 'Enable' has been specified within 'S3Logs' with a value of bool(true)
#       Then: PASS

#
# Constants
#
let GUARDDUTY_DETECTOR_TYPE = "AWS::GuardDuty::Detector"
let INPUT_DOCUMENT = this

#
# Assignments
#
let guardduty_detectors = Resources.*[ Type == %GUARDDUTY_DETECTOR_TYPE ]

#
# Primary Rules
#
rule guardduty_s3_protection_enabled_check when is_cfn_template(%INPUT_DOCUMENT)
                                                %guardduty_detectors not empty {
    check(%guardduty_detectors.Properties)
        <<
        [CT.GUARDDUTY.PR.1]: Require an Amazon GuardDuty detector to have Amazon S3 protection activated
        [FIX]: Set 'DataSources.S3Logs' to true.
        >>
}

rule guardduty_s3_protection_enabled_check when is_cfn_hook(%INPUT_DOCUMENT, %GUARDDUTY_DETECTOR_TYPE) {
    check(%INPUT_DOCUMENT.%GUARDDUTY_DETECTOR_TYPE.resourceProperties)
        <<
        [CT.GUARDDUTY.PR.1]: Require an Amazon GuardDuty detector to have Amazon S3 protection activated
        [FIX]: Set 'DataSources.S3Logs' to true.
        >>
}

#
# Parameterized Rules
#
rule check(guardduty_detector) {
    %guardduty_detector {
        # Scenario: 2
        Enable exists
        Enable == true
        # Scenario: 3
        DataSources exists
        DataSources is_struct
        DataSources {
            # Scenario: 4 and 5
            S3Logs exists
            S3Logs is_struct
            S3Logs {
                Enable exists
                Enable == true
            }
        }
    }
}

#
# Utility Rules
#
rule is_cfn_template(doc) {
    %doc {
        AWSTemplateFormatVersion exists  or
        Resources exists
    }
}

rule is_cfn_hook(doc, RESOURCE_TYPE) {
    %doc.%RESOURCE_TYPE.resourceProperties exists
}