Mutelisting

Sometimes you may find resources that are intentionally configured in a certain way that may be a bad practice but it is all right with it, for example an AWS S3 Bucket open to the internet hosting a web site, or an AWS Security Group with an open port needed in your use case.

Mutelist option works along with other options and adds a MUTED instead of MANUAL, PASS or FAIL to any output format.

You can use -w/--mutelist-file with the path of your mutelist yaml file:

prowler <provider> -w mutelist.yaml

## Mutelist Yaml File Syntax

???+ note For Azure provider, the Account ID is the Subscription Name and the Region is the Location.

???+ note For GCP provider, the Account ID is the Project ID and the Region is the Zone.

???+ note For Kubernetes provider, the Account ID is the Cluster Name and the Region is the Namespace.

The Mutelist file is a YAML file with the following syntax:

    ### Account, Check and/or Region can be * to apply for all the cases.
    ### Resources and tags are lists that can have either Regex or Keywords.
    ### Tags is an optional list that matches on tuples of 'key=value' and are "ANDed" together.
    ### Use an alternation Regex to match one of multiple tags with "ORed" logic.
    ### For each check you can except Accounts, Regions, Resources and/or Tags.
    ###########################  MUTELIST EXAMPLE  ###########################
    Mutelist:
      Accounts:
        "123456789012":
          Checks:
            "iam_user_hardware_mfa_enabled":
              Regions:
                - "us-east-1"
              Resources:
                - "user-1"           # Will ignore user-1 in check iam_user_hardware_mfa_enabled
                - "user-2"           # Will ignore user-2 in check iam_user_hardware_mfa_enabled
            "ec2_*":
              Regions:
                - "*"
              Resources:
                - "*"                 # Will ignore every EC2 check in every account and region
            "*":
              Regions:
                - "*"
              Resources:
                - "test"
              Tags:
                - "test=test"         # Will ignore every resource containing the string "test" and the tags 'test=test' and
                - "project=test|project=stage" # either of ('project=test' OR project=stage) in account 123456789012 and every region

        "*":
          Checks:
            "s3_bucket_object_versioning":
              Regions:
                - "eu-west-1"
                - "us-east-1"
              Resources:
                - "ci-logs"           # Will ignore bucket "ci-logs" AND ALSO bucket "ci-logs-replica" in specified check and regions
                - "logs"              # Will ignore EVERY BUCKET containing the string "logs" in specified check and regions
                - ".+-logs"           # Will ignore all buckets containing the terms ci-logs, qa-logs, etc. in specified check and regions
            "ecs_task_definitions_no_environment_secrets":
              Regions:
                - "*"
              Resources:
                - "*"
              Exceptions:
                Accounts:
                  - "0123456789012"
                Regions:
                  - "eu-west-1"
                  - "eu-south-2"        # Will ignore every resource in check ecs_task_definitions_no_environment_secrets except the ones in account 0123456789012 located in eu-south-2 or eu-west-1
            "*":
              Regions:
                - "*"
              Resources:
                - "*"
              Tags:
                - "environment=dev"    # Will ignore every resource containing the tag 'environment=dev' in every account and region

        "123456789012":
          Checks:
            "*":
              Regions:
                - "*"
              Resources:
                - "*"
              Exceptions:
                Resources:
                  - "test"
                Tags:
                  - "environment=prod"   # Will ignore every resource except in account 123456789012 except the ones containing the string "test" and tag environment=prod

Mute specific AWS regions

If you want to mute failed findings only in specific regions, create a file with the following syntax and run it with prowler aws -w mutelist.yaml:

Mutelist:
  Accounts:
  "*":
    Checks:
      "*":
        Regions:
          - "ap-southeast-1"
          - "ap-southeast-2"
        Resources:
          - "*"

## Default AWS Mutelist For the AWS Provider, Prowler is executed with a Default AWS Mutelist with the AWS Resources that should be muted such as all resources created by AWS Control Tower when setting up a landing zone. You can see this Mutelist file in prowler/config/aws_mutelist.yaml.

Supported AWS Mutelist Locations

The mutelisting flag supports the following AWS locations when using the AWS Provider:

AWS S3 URI

You will need to pass the S3 URI where your Mutelist YAML file was uploaded to your bucket:

prowler aws -w s3://<bucket>/<prefix>/mutelist.yaml

???+ note Make sure that the used AWS credentials have s3:GetObject permissions in the S3 path where the mutelist file is located.

AWS DynamoDB Table ARN

You will need to pass the DynamoDB Mutelist Table ARN:

prowler aws -w arn:aws:dynamodb:<region_name>:<account_id>:table/<table_name>

The DynamoDB Table must have the following String keys:

The Mutelist Table must have the following columns:
- Accounts (String): This field can contain either an Account ID or an * (which applies to all the accounts that use this table as an mutelist).
- Checks (String): This field can contain either a Prowler Check Name or an * (which applies to all the scanned checks).
- Regions (List): This field contains a list of regions where this mutelist rule is applied (it can also contains an * to apply all scanned regions).
- Resources (List): This field contains a list of regex expressions that applies to the resources that are wanted to be muted.
- Tags (List): -Optional- This field contains a list of tuples in the form of 'key=value' that applies to the resources tags that are wanted to be muted.
- Exceptions (Map): -Optional- This field contains a map of lists of accounts/regions/resources/tags that are wanted to be excepted in the mutelist.

The following example will mute all resources in all accounts for the EC2 checks in the regions eu-west-1 and us-east-1 with the tags environment=dev and environment=prod, except the resources containing the string test in the account 012345678912 and region eu-west-1 with the tag environment=prod:

???+ note Make sure that the used AWS credentials have dynamodb:PartiQLSelect permissions in the table.

AWS Lambda ARN

You will need to pass the AWS Lambda Function ARN:

prowler aws -w arn:aws:lambda:REGION:ACCOUNT_ID:function:FUNCTION_NAME

Make sure that the credentials that Prowler uses can invoke the Lambda Function:

- PolicyName: GetMuteList
  PolicyDocument:
    Version: '2012-10-17'
    Statement:
      - Action: 'lambda:InvokeFunction'
        Effect: Allow
        Resource: arn:aws:lambda:REGION:ACCOUNT_ID:function:FUNCTION_NAME

The Lambda Function can then generate an Mutelist dynamically. Here is the code an example Python Lambda Function that generates an Mutelist:

def handler(event, context):
  checks = {}
  checks["vpc_flow_logs_enabled"] = { "Regions": [ "*" ], "Resources": [ "" ], Optional("Tags"): [ "key:value" ] }

  al = { "Mutelist": { "Accounts": { "*": { "Checks": checks } } } }
  return al

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