"@cR.botLocales=" is not allowed as an instance variable name (NameError)

[ktraam]

Describe the Bug

cfn_nag Version: 0.8.10 (build 97717cb)

Amazon Lex V2 Custom Resource with property "CR.botLocales" breaks cfn_nag command and throws error due to not being apart of instance variable names.

Expected Behavior

cfn_nag command runs successfully on the AWS SAM template.

Current Behavior

When running

cfn_nag test.yaml

I receive the following error:

Traceback (most recent call last):
	16: from /usr/local/bin/cfn_nag:23:in `<main>'
	15: from /usr/local/bin/cfn_nag:23:in `load'
	14: from /Library/Ruby/Gems/2.6.0/gems/cfn-nag-0.8.10/bin/cfn_nag:11:in `<top (required)>'
	13: from /Library/Ruby/Gems/2.6.0/gems/cfn-nag-0.8.10/lib/cfn-nag/cfn_nag_executor.rb:30:in `scan'
	12: from /Library/Ruby/Gems/2.6.0/gems/cfn-nag-0.8.10/lib/cfn-nag/cfn_nag_executor.rb:39:in `execute_file_or_piped_scan'
	11: from /Library/Ruby/Gems/2.6.0/gems/cfn-nag-0.8.10/lib/cfn-nag/cfn_nag_executor.rb:60:in `scan_file'
	10: from /Library/Ruby/Gems/2.6.0/gems/cfn-nag-0.8.10/lib/cfn-nag/cfn_nag.rb:87:in `audit'
	 9: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/parser/cfn_parser.rb:43:in `parse'
	 8: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/parser/cfn_parser.rb:86:in `parse_without_parameters'
	 7: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/parser/cfn_parser.rb:165:in `transform_hash_into_model_elements_with_numbers'
	 6: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/parser/cfn_parser.rb:165:in `each'
	 5: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/parser/cfn_parser.rb:173:in `block in transform_hash_into_model_elements_with_numbers'
	 4: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/parser/cfn_parser.rb:255:in `assign_fields_based_upon_properties'
	 3: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/parser/cfn_parser.rb:255:in `each'
	 2: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/parser/cfn_parser.rb:257:in `block in assign_fields_based_upon_properties'
	 1: from /Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/model/model_element.rb:101:in `method_missing'
/Library/Ruby/Gems/2.6.0/gems/cfn-model-0.6.6/lib/cfn-model/model/model_element.rb:101:in `instance_variable_get': `@cR.botLocales=' is not allowed as an instance variable name (NameError)

Reproduction Steps

Generate the following test.yaml file from lex-v2-cfn-cr:

Parameters:
  # add a parameter to your bot template to reference the Custom Resource stack
  LexV2CfnCrStackName:
    Description: >-
      Existing Lex V2 Custom Resource Stack Name. This is used to import the
      Lambda function and IAM role provisioned by the Custom Resource stack
    Type: String
    # If you deployed via the SAR Console and used the defaults, your stack
    # will be named serverlessrepo-lex-v2-cfn-cr. If you deployed manually,
    # make it match the name of your Custom Resource stack
    Default: serverlessrepo-lex-v2-cfn-cr

Resources:
  # LexBot resource contains the bot definition and subresources including:
  # locales, slot types, intents and slots. These subresources use custom
  # attributes with a name prefix: CR.<subresource name>
  # The changes are done to the DRAFT version of the bot.
  # All locales are automatically built
  LexBot:
    Type: Custom::LexBot
    Properties:
      ServiceToken:
        # Points to the Custom Resource Lambda function
        !ImportValue
          Fn::Sub: "${LexV2CfnCrStackName}-LexV2CfnCrFunctionArn"
      # Bot level attributes
      # https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lexv2-models.html#LexModelsV2.Client.create_bot
      botName:
        ZipCodeUpdateBot
      dataPrivacy:
        childDirected: True
      description: Test bot deployed using CloudFormation Custom Resource
      idleSessionTTLInSeconds: 300
      roleArn:
        # Points to the Custom Resource IAM Service Linked role
        !ImportValue
          Fn::Sub: "${LexV2CfnCrStackName}-LexServiceLinkedRole"
      # List of Bot Locale definitions. Requires one or more locales
      CR.botLocales:
        # Locale level attributes
        # https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lexv2-models.html#LexModelsV2.Client.create_bot_locale
        - localeId: en_US
          nluIntentConfidenceThreshold: 0.40
          voiceSettings:
            voiceId: Salli
          # List of optional Slot Type definitions
          CR.slotTypes:
            # Slot Type level attributes
            # https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lexv2-models.html#LexModelsV2.Client.create_slot_type
            - slotTypeName: ZipCodeType
              parentSlotTypeSignature: AMAZON.AlphaNumeric
              valueSelectionSetting:
                resolutionStrategy: OriginalValue
                regexFilter:
                  pattern: '[0-9]{8}'
          # List of Intent definitions. Requires one or more Intents
          CR.intents:
              # Intent level attributes
              # https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lexv2-models.html#LexModelsV2.Client.create_intent
            - intentName: UpdateZipCode
              sampleUtterances:
                - utterance: i want to change my zip code
                - utterance: i have a new zip code
                - utterance: my new zip code is {ZipCode}
               # List of optional Slot definitions. Defined in order of slot priority
              CR.slots:
                # Slot level attributes
                # https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lexv2-models.html#LexModelsV2.Client.create_slot
                - slotName: ZipCode
                  # Slot Type Name is used to dyanmically resolve the ID of the
                  # associated Slot Type defined above
                  CR.slotTypeName: ZipCodeType
                  valueElicitationSetting:
                    slotConstraint: Required
                    promptSpecification:
                      messageGroups:
                        - message:
                            plainTextMessage:
                              value: What is your zipcode?
                      maxRetries: 2
                      allowInterrupt: true
            # The Fallback intent is automatically created by the Lex service
            # This will update the default fallback intent
            - intentName: FallbackIntent
              description: Default fallback intent when no other intent matches
              intentClosingSetting:
                closingResponse:
                  messageGroups:
                    - message:
                        plainTextMessage:
                          value: Sorry I am having trouble understanding.

  # Creates an immutable Bot Version
  LexBotVersion:
    # Bot versions are deleted by the Bot on Stack deletions. This deletion
    # policy speeds up deletes
    DeletionPolicy: Retain
    # Version number changes between updates which cause a CloudFormation
    # delete event since the version number is the physical resource ID.
    # The following policies prevents deletion events to retain the bot versions
    # and speed up updates
    UpdateReplacePolicy: Retain
    Type: Custom::LexBotVersion
    Properties:
      ServiceToken:
        !ImportValue
          Fn::Sub: "${LexV2CfnCrStackName}-LexV2CfnCrFunctionArn"
      # Bot Version level attributes
      # https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lexv2-models.html#LexModelsV2.Client.create_bot_version
      botId: !Ref LexBot
      # botVersionLocaleSpecification is derived from the bot locales
      # this controls which locales are added to the version
      CR.botLocaleIds: !GetAtt LexBot.botLocaleIds
      # lastUpdatedDateTime is used to detect changes in the bot
      CR.lastUpdatedDateTime: !GetAtt LexBot.lastUpdatedDateTime

  # Provisions a Bot Alias that points to a version
  LexBotAlias:
    # Bot aliases are deleted by the Bot on Stack deletions. This deletion
    # policy speeds up deletes
    DeletionPolicy: Retain
    Type: Custom::LexBotAlias
    Properties:
      ServiceToken:
        !ImportValue
          Fn::Sub: "${LexV2CfnCrStackName}-LexV2CfnCrFunctionArn"
      # https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lexv2-models.html#LexModelsV2.Client.create_bot_alias
      botId: !Ref LexBot
      botAliasName: live
      # points to the latest version of the resource above
      botVersion: !Ref LexBotVersion
      # enable locales under this alias
      botAliasLocaleSettings:
        en_US:
          enabled: True

Outputs:
  LexBotId:
    Description: Lex Bot ID
    Value: !Ref LexBot

  LexBotLocaleIds:
    Description: Lex Bot Locale IDs
    Value: !Join [",", !GetAtt LexBot.botLocaleIds]

  LexBotLatestVersion:
    Description: Latest Lex Bot Version ID
    Value: !Ref LexBotVersion

  LexBotAliasId:
    Description: Lex Bot Alias ID
    Value: !Ref LexBotAlias

Run the command:

cfn_nag test.yaml

Possible Solution

N/A

Additional Information / Context

Ruby Version

3.0.3

OS

macOS Big Sur 11.6.5