feat(scan-type): AWS Resource ARNs based scan (#1807)

Co-authored-by: Pepe Fagoaga <pepe@verica.io>

docs/tutorials/aws/resource-arn-based-scan.md

@@ -0,0 +1,9 @@
+# Resource ARNs based Scan
+
+Prowler allows you to scan only the resources with specific AWS Resource ARNs. This can be done with the flag `--resource-arn` followed by one or more [Amazon Resource Names (ARNs)](https://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html) separated by space:
+
+```
+prowler aws --resource-arn arn:aws:iam::012345678910:user/test arn:aws:ec2:us-east-1:123456789012:vpc/vpc-12345678
+```
+
+This example will only scan the two resources with those ARNs.

docs/tutorials/aws/tag-based-scan.md

@@ -1,9 +1,9 @@
 # Tags-based Scan
 
-Prowler allows you to scan only the resources that contain specific tags. This can be done with the flag `-t/--scan-tags` followed by the tags `Key=Value` separated by space:
+Prowler allows you to scan only the resources that contain specific tags. This can be done with the flag `--resource-tags` followed by the tags `Key=Value` separated by space:
 
 ```
-prowler aws --scan-tags Environment=dev Project=prowler
+prowler aws --resource-tags Environment=dev Project=prowler
 ```
 
 This example will only scan the resources that contains both tags.

mkdocs.yml

@@ -45,6 +45,7 @@ nav:
           - AWS CloudShell: tutorials/aws/cloudshell.md
           - Checks v2 to v3 Mapping: tutorials/aws/v2_to_v3_checks_mapping.md
           - Tag-based Scan: tutorials/aws/tag-based-scan.md
+          - Resource ARNs based Scan: tutorials/aws/resource-arn-based-scan.md
         - Azure:
           - Authentication: tutorials/azure/authentication.md
           - Subscriptions: tutorials/azure/subscriptions.md

prowler/__main__.py

@@ -99,6 +99,9 @@ def prowler():
             )
             sys.exit()
 
+    # Set the audit info based on the selected provider
+    audit_info = set_provider_audit_info(provider, args.__dict__)
+
     # Load checks to execute
     checks_to_execute = load_checks_to_execute(
         bulk_checks_metadata,
@@ -110,13 +113,14 @@ def prowler():
         compliance_framework,
         categories,
         provider,
+        audit_info,
     )
 
     # Exclude checks if -e/--excluded-checks
     if excluded_checks:
         checks_to_execute = exclude_checks_to_run(checks_to_execute, excluded_checks)
 
-    # Exclude services if -s/--excluded-services
+    # Exclude services if --excluded-services
     if excluded_services:
         checks_to_execute = exclude_services_to_run(
             checks_to_execute, excluded_services, provider
@@ -130,9 +134,6 @@ def prowler():
         print_checks(provider, checks_to_execute, bulk_checks_metadata)
         sys.exit()
 
-    # Set the audit info based on the selected provider
-    audit_info = set_provider_audit_info(provider, args.__dict__)
-
     # Parse content from Allowlist file and get it, if necessary, from S3
     if provider == "aws" and args.allowlist_file:
         allowlist_file = parse_allowlist_file(audit_info, args.allowlist_file)

prowler/lib/check/checks_loader.py

@@ -4,6 +4,7 @@ from prowler.lib.check.check import (
     recover_checks_from_provider,
 )
 from prowler.lib.logger import logger
+from prowler.providers.aws.lib.audit_info.models import AWS_Audit_Info
 
 
 # Generate the list of checks to execute
@@ -18,10 +19,25 @@ def load_checks_to_execute(
     compliance_frameworks: list,
     categories: set,
     provider: str,
+    audit_info: AWS_Audit_Info,
 ) -> set:
     """Generate the list of checks to execute based on the cloud provider and input arguments specified"""
     checks_to_execute = set()
 
+    # Handle if there are audit resources so only their services are executed
+    if audit_info.audit_resources:
+        service_list = []
+        for resource in audit_info.audit_resources:
+            service = resource.split(":")[2]
+            # Parse services when they are different in the ARNs
+            if service == "lambda":
+                service = "awslambda"
+            if service == "elasticloadbalancing":
+                service = "elb"
+            elif service == "logs":
+                service = "cloudwatch"
+            service_list.append(service)
+
     # Handle if there are checks passed using -c/--checks
     if check_list:
         for check_name in check_list:

prowler/lib/cli/parser.py

@@ -4,6 +4,14 @@ from argparse import RawTextHelpFormatter
 
 from prowler.config.config import default_output_directory, prowler_version
 from prowler.providers.aws.aws_provider import get_aws_available_regions
+from prowler.providers.aws.lib.arn.arn import is_valid_arn
+
+
+def arn_type(arn: str) -> bool:
+    """arn_type returns a string ARN if it is valid and raises an argparse.ArgumentError if not."""
+    if not is_valid_arn(arn):
+        raise argparse.ArgumentError("Invalid ARN")
+    return arn
 
 
 class ProwlerArgumentParser:
@@ -343,14 +351,23 @@ Detailed documentation at https://docs.prowler.cloud
             default=None,
             help="Path for allowlist yaml file. See example prowler/config/allowlist.yaml for reference and format. It also accepts AWS DynamoDB Table or Lambda ARNs or S3 URIs, see more in https://docs.prowler.cloud/en/latest/tutorials/allowlist/",
         )
-        # Allowlist
-        audit_tags_subparser = aws_parser.add_argument_group("Tags-based Scan")
-        audit_tags_subparser.add_argument(
-            "-t",
-            "--scan-tags",
+        # Based Scans
+        aws_based_scans_subparser = aws_parser.add_argument_group("AWS Based Scans")
+        aws_based_scans_parser = (
+            aws_based_scans_subparser.add_mutually_exclusive_group()
+        )
+        aws_based_scans_parser.add_argument(
+            "--resource-tags",
             nargs="+",
             default=None,
-            help="Scan only resources with specific tags (Key=Value), e.g., Environment=dev Project=prowler",
+            help="Scan only resources with specific AWS Tags (Key=Value), e.g., Environment=dev Project=prowler",
+        )
+        aws_based_scans_parser.add_argument(
+            "--resource-arn",
+            nargs="+",
+            type=arn_type,
+            default=None,
+            help="Scan only resources with specific AWS Resource ARNs, e.g., arn:aws:iam::012345678910:user/test arn:aws:ec2:us-east-1:123456789012:vpc/vpc-12345678",
         )
 
     def __init_azure_parser__(self):

prowler/providers/aws/lib/arn/arn.py

@@ -1,3 +1,5 @@
+import re
+
 from arnparse import arnparse
 
 from prowler.providers.aws.lib.arn.error import (
@@ -43,3 +45,9 @@ def arn_parsing(arn):
                 raise RoleArnParsingEmptyResource
             else:
                 return arn_parsed
+
+
+def is_valid_arn(arn: str) -> bool:
+    """is_valid_arn returns True or False whether the given AWS ARN (Amazon Resource Name) is valid or not."""
+    regex = r"^arn:aws(-cn|-us-gov)?:[a-zA-Z0-9\-]+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:[a-zA-Z0-9\-_\/]+(:\d+)?$"
+    return re.match(regex, arn) is not None

prowler/providers/common/audit_info.py

@@ -5,7 +5,11 @@ from boto3 import client, session
 from colorama import Fore, Style
 
 from prowler.lib.logger import logger
-from prowler.providers.aws.aws_provider import AWS_Provider, assume_role
+from prowler.providers.aws.aws_provider import (
+    AWS_Provider,
+    assume_role,
+    generate_regional_clients,
+)
 from prowler.providers.aws.lib.arn.arn import arn_parsing
 from prowler.providers.aws.lib.audit_info.audit_info import current_audit_info
 from prowler.providers.aws.lib.audit_info.models import (
@@ -237,10 +241,16 @@ Caller Identity ARN: {Fore.YELLOW}[{audit_info.audited_identity_arn}]{Style.RESE
             self.print_audit_credentials(current_audit_info)
 
         # Parse Scan Tags
-        input_scan_tags = arguments.get("scan_tags")
-        current_audit_info.audit_resources = get_tagged_resources(
-            input_scan_tags, current_audit_info
-        )
+        if arguments.get("resource_tags"):
+            input_resource_tags = arguments.get("resource_tags")
+            current_audit_info.audit_resources = get_tagged_resources(
+                input_resource_tags, current_audit_info
+            )
+
+        # Parse Input Resource ARNs
+        if arguments.get("resource_arn"):
+            current_audit_info.audit_resources = arguments.get("resource_arn")
+
         return current_audit_info
 
     def set_azure_audit_info(self, arguments) -> Azure_Audit_Info:
@@ -294,27 +304,30 @@ def set_provider_audit_info(provider: str, arguments: dict):
         return provider_audit_info
 
 
-def get_tagged_resources(input_scan_tags: list, current_audit_info: AWS_Audit_Info):
+def get_tagged_resources(input_resource_tags: list, current_audit_info: AWS_Audit_Info):
     """
     get_tagged_resources returns a list of the resources that are going to be scanned based on the given input tags
     """
     try:
-        scan_tags = []
+        resource_tags = []
         tagged_resources = []
-        if input_scan_tags:
-            for tag in input_scan_tags:
-                key = tag.split("=")[0]
-                value = tag.split("=")[1]
-                scan_tags.append({"Key": key, "Values": [value]})
-            # Get Resources with scan_tags for all regions
-            for region in current_audit_info.audited_regions:
-                client = current_audit_info.audit_session.client(
-                    "resourcegroupstaggingapi", region_name=region
-                )
-                get_resources_paginator = client.get_paginator("get_resources")
-                for page in get_resources_paginator.paginate(TagFilters=scan_tags):
+        for tag in input_resource_tags:
+            key = tag.split("=")[0]
+            value = tag.split("=")[1]
+            resource_tags.append({"Key": key, "Values": [value]})
+        # Get Resources with resource_tags for all regions
+        for regional_client in generate_regional_clients(
+            "resourcegroupstaggingapi", current_audit_info
+        ).values():
+            try:
+                get_resources_paginator = regional_client.get_paginator("get_resources")
+                for page in get_resources_paginator.paginate(TagFilters=resource_tags):
                     for resource in page["ResourceTagMappingList"]:
                         tagged_resources.append(resource["ResourceARN"])
+            except Exception as error:
+                logger.error(
+                    f"{error.__class__.__name__}[{error.__traceback__.tb_lineno}]: {error}"
+                )
     except Exception as error:
         logger.critical(
             f"{error.__class__.__name__}[{error.__traceback__.tb_lineno}]: {error}"

tests/lib/cli/parser_test.py

@@ -54,7 +54,7 @@ class Test_Parser:
         assert not parsed.output_bucket_no_assume
         assert not parsed.shodan
         assert not parsed.allowlist_file
-        assert not parsed.scan_tags
+        assert not parsed.resource_tags
 
     def test_default_parser_no_arguments_azure(self):
         provider = "azure"
@@ -796,23 +796,33 @@ class Test_Parser:
         parsed = self.parser.parse(command)
         assert parsed.allowlist_file == allowlist_file
 
-    def test_aws_parser_scan_tags_short(self):
-        argument = "-t"
-        scan_tag = "Key=Value"
-        command = [prowler_command, argument, scan_tag]
-        parsed = self.parser.parse(command)
-        assert len(parsed.scan_tags) == 1
-        assert scan_tag in parsed.scan_tags
-
-    def test_aws_parser_scan_tags_long(self):
-        argument = "--scan-tags"
+    def test_aws_parser_resource_tags(self):
+        argument = "--resource-tags"
         scan_tag1 = "Key=Value"
         scan_tag2 = "Key2=Value2"
         command = [prowler_command, argument, scan_tag1, scan_tag2]
         parsed = self.parser.parse(command)
-        assert len(parsed.scan_tags) == 2
-        assert scan_tag1 in parsed.scan_tags
-        assert scan_tag2 in parsed.scan_tags
+        assert len(parsed.resource_tags) == 2
+        assert scan_tag1 in parsed.resource_tags
+        assert scan_tag2 in parsed.resource_tags
+
+    def test_aws_parser_resource_arn(self):
+        argument = "--resource-arn"
+        resource_arn1 = "arn:aws:iam::012345678910:user/test"
+        resource_arn2 = "arn:aws:ec2:us-east-1:123456789012:vpc/vpc-12345678"
+        command = [prowler_command, argument, resource_arn1, resource_arn2]
+        parsed = self.parser.parse(command)
+        assert len(parsed.resource_arn) == 2
+        assert resource_arn1 in parsed.resource_arn
+        assert resource_arn2 in parsed.resource_arn
+
+    def test_aws_parser_wrong_resource_arn(self):
+        argument = "--resource-arn"
+        resource_arn = "arn:azure:iam::account:user/test"
+        command = [prowler_command, argument, resource_arn]
+        with pytest.raises(SystemExit) as ex:
+            self.parser.parse(command)
+        assert ex.type == SystemExit
 
     def test_parser_azure_auth_sp(self):
         argument = "--sp-env-auth"

tests/providers/aws/lib/arn/arn_test.py

@@ -1,6 +1,6 @@
 import sure  # noqa
 
-from prowler.providers.aws.lib.arn.arn import arn_parsing
+from prowler.providers.aws.lib.arn.arn import arn_parsing, is_valid_arn
 
 ACCOUNT_ID = "123456789012"
 RESOURCE_TYPE = "role"
@@ -31,3 +31,11 @@ class Test_ARN_Parsing:
             parsed_arn.account_id.should.equal(test["expected"]["account_id"])
             parsed_arn.resource_type.should.equal(test["expected"]["resource_type"])
             parsed_arn.resource.should.equal(test["expected"]["resource"])
+
+    def test_is_valid_arn(self):
+        assert is_valid_arn("arn:aws:iam::012345678910:user/test")
+        assert is_valid_arn("arn:aws-cn:ec2:us-east-1:123456789012:vpc/vpc-12345678")
+        assert is_valid_arn("arn:aws-us-gov:s3:::bucket")
+        assert not is_valid_arn("arn:azure:::012345678910:user/test")
+        assert not is_valid_arn("arn:aws:iam::account:user/test")
+        assert not is_valid_arn("arn:aws:::012345678910:resource")