When should I attach AmazonElasticFileSystemClientReadOnlyAccess?

The reference page says you can attach it to your users, groups and roles, and the description says it provides read only client access to an Amazon EFS file system. Attach it where that scope is intended.

What are the security risks of AmazonElasticFileSystemClientReadOnlyAccess?

The policy grants no write actions, but it applies to all resources, so the client access covers every EFS file system. AWS managed policies don't grant least privilege permissions, and you must consider the security risk of granting principals more permissions than they need. AWS updates to the policy affect every identity it is attached to.

AmazonElasticFileSystemClientReadOnlyAccess

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Summary

Provides read only client access to an Amazon EFS file system.

Permissions imported from the AWS Managed Policy Reference Guide; other sections reviewed against the listed AWS sources.

Identity

ARN: arn:aws:iam::aws:policy/AmazonElasticFileSystemClientReadOnlyAccess
Default version: v1
Created: 2020-01-13
Last edited: 2020-01-13
Services: elasticfilesystem

Control-plane actions (2)

By access level: 2 Read.

Control-plane actions by service
Service	Granted	Access levels and limits	Granted by
EFS	2 of 38	2 Read; 0 restricted, 0 conditional	elasticfilesystem:ClientMount, elasticfilesystem:DescribeMountTargets

EFS: 2 actions

elasticfilesystem:ClientMount (Read)
elasticfilesystem:DescribeMountTargets (Read)

Data-plane actions (0)

By access level: none.

This policy grants no actions in this plane.

Excluded and conditional actions

No patterns are excluded by NotAction or Deny statements.

Resource scope and attachment

Resource scope across granted actions: all-resources.

Can be attached: Yes, to users, groups and roles.

Why this tier

Grants only List and Read actions.

Guidance

Practical scope

One statement on Resource "*" allows elasticfilesystem:ClientMount and elasticfilesystem:DescribeMountTargets. It has no write or root client actions.

Use cases

Give an IAM identity read only client access to an Amazon EFS file system.

Best practices

AWS managed policies don't grant least privilege permissions. The IAM User Guide suggests using IAM Access Analyzer to see which permissions principals actually use, then writing a custom policy or generating one with only the required permissions.

Security considerations

The policy grants no write actions, but it applies to Resource "*", so the client access covers every EFS file system.
You cannot change the permissions in an AWS managed policy. If AWS updates the policy, the update affects every user, group and role it is attached to.

Assignment guidance

You can attach this policy to your users, groups and roles. The reference page also links to guidance on creating a permission set using AWS managed policies in IAM Identity Center. It fits where read only client access to Amazon EFS is intended.

Same service

Same domain

Frequently asked questions

When should I attach AmazonElasticFileSystemClientReadOnlyAccess?: The reference page says you can attach it to your users, groups and roles, and the description says it provides read only client access to an Amazon EFS file system. Attach it where that scope is intended.
What does AmazonElasticFileSystemClientReadOnlyAccess grant?: It allows elasticfilesystem:ClientMount and elasticfilesystem:DescribeMountTargets on all resources. It has no write or root client actions.
What are the security risks of AmazonElasticFileSystemClientReadOnlyAccess?: The policy grants no write actions, but it applies to all resources, so the client access covers every EFS file system. AWS managed policies don't grant least privilege permissions, and you must consider the security risk of granting principals more permissions than they need. AWS updates to the policy affect every identity it is attached to.

Policy JSON

Download policy.json

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "elasticfilesystem:ClientMount",
        "elasticfilesystem:DescribeMountTargets"
      ],
      "Resource": "*"
    }
  ]
}

Version history

Current version v1, edited by AWS on 2020-01-13. Version history is recorded from 2026-11-11. Earlier versions are in the IAM console under Policy versions.

Attach snippets

AWS CLI

aws iam attach-role-policy --role-name ROLE_NAME --policy-arn arn:aws:iam::aws:policy/AmazonElasticFileSystemClientReadOnlyAccess
aws iam attach-user-policy --user-name USER_NAME --policy-arn arn:aws:iam::aws:policy/AmazonElasticFileSystemClientReadOnlyAccess
aws iam attach-group-policy --group-name GROUP_NAME --policy-arn arn:aws:iam::aws:policy/AmazonElasticFileSystemClientReadOnlyAccess

CloudFormation

Resources:
  ExampleRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument: {}  # replace with your trust policy
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/AmazonElasticFileSystemClientReadOnlyAccess

Terraform

resource "aws_iam_role_policy_attachment" "amazonelasticfilesystemclientreadonlyaccess" {
  role       = aws_iam_role.example.name
  policy_arn = "arn:aws:iam::aws:policy/AmazonElasticFileSystemClientReadOnlyAccess"
}

CDK (TypeScript)

role.addManagedPolicy(
  iam.ManagedPolicy.fromAwsManagedPolicyName("AmazonElasticFileSystemClientReadOnlyAccess"),
);

Sources

AmazonElasticFileSystemClientReadOnlyAccess (AWS Managed Policy Reference Guide) (retrieved 2026-11-13; supports summary, practicalScope, securityConsiderations, assignmentGuidance, faqs, useCases)
Managed policies and inline policies (IAM User Guide) (retrieved 2026-11-12; supports securityConsiderations, faqs)
AWS managed policies for job functions (IAM User Guide) (retrieved 2026-11-12; supports bestPractices, faqs)