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aws-lint-iam-policies

Runs IAM policy linting and security checks against either a single AWS account or a set of member accounts of an AWS Organization. Dumps all supported identity-based and resource-based policies to a local directory and reports on those that may violate security best practices or contain errors. See the accompanying blog post here.

The script makes use of three mechanisms:

  1. AWS IAM Access Analyzer policy validation, which is mostly known for showing recommendations when manually editing IAM policies on the AWS Console UI. The checks are created and maintained by AWS and are described closer here.

  2. AWS IAM Access Analyzer checks for public access, which test whether resource-based policies grant unrestricted public access (e.g., to S3 buckets, SQS queues, etc.). This is closer described here.

  3. Custom policy checks that report on trust relationships to other AWS accounts and to identity providers. Please note that these are only basic checks. They neither make use of automated reasoning nor evaluate the meaning of policy conditions.

Usage

Make sure you have AWS credentials configured for your targeted environment. This can either be done using environment variables or by specifying a named profile in the optional --profile argument.

By default, all supported policy types and all regions are analyzed in the targeted AWS account(s). See the list of supported arguments below, in case you want to reduce coverage.

Example invocations:

pip install -r requirements.txt

python aws_lint_iam_policies.py --scope ACCOUNT

python aws_lint_iam_policies.py --scope ACCOUNT --include-policy-types s3_bucket_policies,kms_key_policies

python aws_lint_iam_policies.py --scope ORGANIZATION --member-accounts-role OrganizationAccountAccessRole

python aws_lint_iam_policies.py --scope ORGANIZATION --member-accounts-role OrganizationAccountAccessRole --exclude-accounts 112233445566,998877665544

Supported arguments

--list-policy-types
    list all supported policy types and exit
--scope {ACCOUNT,ORGANIZATION}
    target either an individual account or all accounts of an AWS Organization
--member-accounts-role MEMBER_ACCOUNTS_ROLE
    IAM role name present in member accounts that can be assumed from the Organizations management account
--exclude-policy-types EXCLUDE_POLICY_TYPES
    do not target the specified comma-separated list of policy types
--include-policy-types INCLUDE_POLICY_TYPES
    only target the specified comma-separated list of policy types
--exclude-regions EXCLUDE_REGIONS
    do not target the specified comma-separated list of region names
--include-regions INCLUDE_REGIONS
    only target the specified comma-separated list of region names
--exclude-accounts EXCLUDE_ACCOUNTS
    do not target the specified comma-separated list of account IDs
--include-accounts INCLUDE_ACCOUNTS
    only target the specified comma-separated list of account IDs
--exclude-ous EXCLUDE_OUS
    do not target the specified comma-separated list of Organizations OU IDs
--include-ous INCLUDE_OUS
    only target the specified comma-separated list of Organizations OU IDs
--exclude-finding-issue-codes EXCLUDE_FINDING_ISSUE_CODES
    do not report the specified comma-separated list of finding issue codes
--include-finding-issue-codes INCLUDE_FINDING_ISSUE_CODES
    only report the specified comma-separated list of finding issue codes
--profile PROFILE
    named AWS profile to use
--result-name RESULT_NAME
    result name to use instead of the run timestamp

Supported policy types

The following IAM policy types are analyzed:

Example result file

Results are written to a JSON file. Findings are grouped by finding type and finding issue code.

{
  "_metadata": {
    "invocation": "aws_lint_iam_policies.py --scope ACCOUNT",
    "account_id": "123456789012",
    "principal": "arn:aws:iam::123456789012:user/user1",
    "scope": "ACCOUNT",
    "run_timestamp": "20230729093927",
    "stats": {
      "number_of_policies_analyzed": 61,
      "number_of_results_collected": 3
    },
    "errors": []
  },
  "results": {
    "SECURITY_WARNING": {
      "PASS_ROLE_WITH_STAR_IN_RESOURCE": [
        {
          "account_id": "123456789012",
          "region": "us-east-1",
          "source_service": "iam",
          "resource_type": "AWS::IAM::UserPolicy",
          "resource_name": "user1:inlinepolicy",
          "resource_arn": "arn:aws:iam::123456789012:user/user1",
          "policy_dump_file_name": "123456789012_us-east-1_iam_AWS_IAM_UserPolicy_user1_inlinepolicy_0.json",
          "finding_type": "SECURITY_WARNING",
          "finding_issue_code": "PASS_ROLE_WITH_STAR_IN_RESOURCE",
          "finding_description": "Using the iam:PassRole action with wildcards (*) in the resource can be overly permissive because it allows iam:PassRole permissions on multiple resources. We recommend that you specify resource ARNs or add the iam:PassedToService condition key to your statement.",
          "finding_link": "https://docs.aws.amazon.com/IAM/latest/UserGuide/access-analyzer-reference-policy-checks.html#access-analyzer-reference-policy-checks-security-warning-pass-role-with-star-in-resource"
        }
      ],
      "TRUSTED_WILDCARD_PRINCIPAL": [
        {
          "account_id": "123456789012",
          "region": "eu-central-1",
          "source_service": "s3",
          "resource_type": "AWS::S3::Bucket",
          "resource_name": "bucket1",
          "resource_arn": "arn:aws:s3:::bucket1",
          "policy_dump_file_name": "123456789012_eu-central-1_s3_AWS_S3_Bucket_bucket1_0.json",
          "finding_type": "SECURITY_WARNING",
          "finding_issue_code": "TRUSTED_WILDCARD_PRINCIPAL",
          "finding_description": "The policy trusts the wildcard principal ('*'). A review is recommended to determine whether this is the desired setup.",
          "finding_link": "https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies-cross-account-resource-access.html"
        }
      ]
    },
    "WARNING": {
      "MISSING_VERSION": [
        {
          "account_id": "123456789012",
          "region": "eu-central-1",
          "source_service": "sqs",
          "resource_type": "AWS::SQS::QueuePolicy",
          "resource_name": "queue1",
          "resource_arn": "arn:aws:sqs:eu-central-1:123456789012:queue1",
          "policy_dump_file_name": "123456789012_eu-central-1_sqs_AWS_SQS_QueuePolicy_queue1_0.json",
          "finding_type": "WARNING",
          "finding_issue_code": "MISSING_VERSION",
          "finding_description": "We recommend that you specify the Version element to help you with debugging permission issues.",
          "finding_link": "https://docs.aws.amazon.com/IAM/latest/UserGuide/access-analyzer-reference-policy-checks.html#access-analyzer-reference-policy-checks-general-warning-missing-version"
        }
      ]
    }
  }
}

Notes

Related projects

If this script does not quite fulfill your needs, consider looking at the following projects that offer similar functionality: