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AWS WAF and AWS Shield Advanced
Developer Guide (API Version 2015-08-24)

Overview of Managing Access Permissions to Your AWS WAF Resources

Every AWS resource is owned by an AWS account, and permissions to create or access a resource are governed by permissions policies. An account administrator can attach permissions policies to IAM identities (that is, users, groups, and roles), and some services also support attaching permissions policies to resources.

Note

An account administrator (or administrator user) is a user with administrator privileges. For more information, see IAM Best Practices in the IAM User Guide.

When granting permissions, you decide who is getting the permissions, the resources they get permissions for, and the specific operations that you want to allow on those resources.

Topics

AWS WAF Resources and Operations

In AWS WAF, the resources are web ACLs and rules. AWS WAF also supports conditions such as byte match, IP match, and size constraint.

These resources and conditions have unique Amazon Resource Names (ARNs) associated with them as shown in the following table.

Name in WAF Console Name in WAF SDK/CLI ARN Format
Web ACL WebACL

arn:aws:waf::account:webacl/ID

Rule Rule

arn:aws:waf::account:rule/ID

String match condition ByteMatchSet

arn:aws:waf::account:bytematchset/ID

SQL injection match condition SqlInjectionMatchSet arn:aws:waf::account:sqlinjectionset/ID
Size constraint condition SizeConstraintSet arn:aws:waf::account:sizeconstraintset/ID
IP match condition IPSet arn:aws:waf::account:ipset/ID
Cross-site scripting match condition XssMatchSet arn:aws:waf::account:xssmatchset/ID

To allow or deny access to a subset of AWS WAF resources, include the ARN of the resource in the resource element of your policy. The ARNs for AWS WAF have the following format:

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arn:aws:waf::account:resource/ID

Replace the account, resource, and ID variables with valid values. Valid values can be the following:

  • account: The ID of your AWS account. You must specify a value.

  • resource: The type of AWS WAF resource.

  • ID: The ID of the AWS WAF resource, or a wildcard (*) to indicate all resources of the specified type that are associated with the specified AWS account.

For example, the following ARN specifies all web ACLs for the account 111122223333:

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arn:aws:waf::111122223333:webacl/*

For more information, see Resources in the IAM User Guide.

AWS WAF provides a set of operations to work with AWS WAF resources. For a list of available operations, see Actions.

Understanding Resource Ownership

A resource owner is the AWS account that creates the resource. That is, the resource owner is the AWS account of the principal entity (the root account, an IAM user, or an IAM role) that authenticates the request that creates the resource. The following examples illustrate how this works:

  • If you use the root account credentials of your AWS account to create an AWS WAF resource, your AWS account is the owner of the resource.

  • If you create an IAM user in your AWS account and grant permissions to create an AWS WAF resource to that user, the user can create an AWS WAF resource. However, your AWS account, to which the user belongs, owns the AWS WAF resource.

  • If you create an IAM role in your AWS account with permissions to create an AWS WAF resource, anyone who can assume the role can create an AWS WAF resource. Your AWS account, to which the role belongs, owns the AWS WAF resource.

Managing Access to Resources

A permissions policy describes who has access to what. The following section explains the available options for creating permissions policies.

Note

This section discusses using IAM in the context of AWS WAF. It doesn't provide detailed information about the IAM service. For complete IAM documentation, see What Is IAM? in the IAM User Guide. For information about IAM policy syntax and descriptions, see AWS IAM Policy Reference in the IAM User Guide.

Policies that are attached to an IAM identity are known as identity-based policies and policies that are attached to a resource are known as resource-based policies. AWS WAF supports only identity-based policies.

Topics

Identity-Based Policies (IAM Policies)

You can attach policies to IAM identities. For example, you can do the following:

  • Attach a permissions policy to a user or a group in your account – An account administrator can use a permissions policy that is associated with a particular user to grant permissions for that user to create an AWS WAF resource.

  • Attach a permissions policy to a role (grant cross-account permissions) – You can attach an identity-based permissions policy to an IAM role to grant cross-account permissions. For example, the administrator in Account A can create a role to grant cross-account permissions to another AWS account (for example, Account B) or an AWS service as follows:

    1. Account A administrator creates an IAM role and attaches a permissions policy to the role that grants permissions on resources in Account A.

    2. Account A administrator attaches a trust policy to the role identifying Account B as the principal who can assume the role.

    3. Account B administrator can then delegate permissions to assume the role to any users in Account B. Doing this allows users in Account B to create or access resources in Account A. The principal in the trust policy also can be an AWS service principal if you want to grant an AWS service permissions to assume the role.

    For more information about using IAM to delegate permissions, see Access Management in the IAM User Guide.

The following is an example policy that grants permissions for the waf:ListRules action on all resources. In the current implementation, AWS WAF doesn't support identifying specific resources using the resource ARNs (also referred to as resource-level permissions) for some of the API actions, so you must specify a wildcard character (*):

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{ "Version": "2012-10-17", "Statement": [ { "Sid": "ListRules", "Effect": "Allow", "Action": [ "waf:ListRules" ], "Resource": "*" } ] }

For more information about using identity-based policies with AWS WAF, see Using Identity-Based Policies (IAM Policies) for AWS WAF. For more information about users, groups, roles, and permissions, see Identities (Users, Groups, and Roles) in the IAM User Guide.

Resource-Based Policies

Other services, such as Amazon S3, also support resource-based permissions policies. For example, you can attach a policy to an S3 bucket to manage access permissions to that bucket. AWS WAF doesn't support resource-based policies.

Specifying Policy Elements: Actions, Effects, Resources, and Principals

For each AWS WAF resource (see AWS WAF Resources and Operations), the service defines a set of API operations (see AWS WAF API Permissions: Actions, Resources, and Conditions Reference). To grant permissions for these API operations, AWS WAF defines a set of actions that you can specify in a policy. Note that performing an API operation can require permissions for more than one action. When granting permissions for specific actions, you also identify the resource on which the actions are allowed or denied.

The following are the most basic policy elements:

  • Resource – In a policy, you use an Amazon Resource Name (ARN) to identify the resource to which the policy applies. For more information, see AWS WAF Resources and Operations.

  • Action – You use action keywords to identify resource operations that you want to allow or deny. For example, the waf:CreateRule permission allows the user permissions to perform the AWS WAF CreateRule operation.

  • Effect – You specify the effect when the user requests the specific action. This can be either allow or deny. If you don't explicitly grant access to allow a resource, access is implicitly denied. You also can explicitly deny access to a resource, which you might do to make sure that a user cannot access it, even if a different policy grants access.

  • Principal – In identity-based policies (IAM policies), the user that the policy is attached to is the implicit principal. AWS WAF doesn't support resource-based policies.

To learn more about IAM policy syntax and descriptions, see AWS IAM Policy Reference in the IAM User Guide.

For a table that shows all the AWS WAF API actions and the resources that they apply to, see AWS WAF API Permissions: Actions, Resources, and Conditions Reference.

Specifying Conditions in a Policy

When you grant permissions, you can use the IAM policy language to specify the conditions when a policy should take effect. For example, you might want a policy to be applied only after a specific date. For more information about specifying conditions in a policy language, see Condition in the IAM User Guide.

To express conditions, you use predefined condition keys. There are no condition keys specific to AWS WAF. However, there are AWS-wide condition keys that you can use as appropriate. For a complete list of AWS-wide keys, see Available Keys for Conditions in the IAM User Guide.