AWS IAM Best Practices

AWS IAM Best Practices

AWS recommends the following AWS Identity and Access Management service – IAM Best Practices to secure AWS resources

Root Account – Don’t use & Lock away access keys

  • Do not use the AWS Root account which has full access to all the AWS resources and services including the Billing information.
  • Permissions associated with the AWS Root account cannot be restricted.
  • Do not generate the access keys, if not required
  • If already generated and not needed, delete the access keys.
  • If access keys are needed, rotate (change) the access key regularly
  • Never share the Root account credentials or access keys, instead create IAM users or Roles to grant granular access
  • Enable AWS multifactor authentication (MFA) on the AWS account

User – Create individual IAM users

  • Don’t use the AWS root account credentials to access AWS, and don’t share the credentials with anyone else.
  • Start by creating an IAM User with an Administrator role that has access to all resources as the Root except the account’s security credentials.
  • Create individual users for anyone who needs access to your AWS account and gives each user unique credentials and grant different permissions.

Groups – Use groups to assign permissions to IAM users

  • Instead of defining permissions for individual IAM users, create groups and define the relevant permissions for each group as per the job function, and then associate IAM users to those groups.
  • Users in an IAM group inherit the permissions assigned to the group and a User can belong to multiple groups
  • It is much easier to add new users, remove users and modify the permissions of a group of users.

Permission – Grant least privilege

  • IAM user, by default, is created with no permissions
  • Users should be granted LEAST PRIVILEGE as required to perform a task.
  • Starting with minimal permissions and adding to the permissions as required to perform the job function is far better than granting all access and trying to then tighten it down.

Passwords – Enforce strong password policy for users

  • Enforce users to create strong passwords and enforce them to rotate their passwords periodically.
  • Enable a strong password policy to define password requirements forcing users to create passwords with requirements like at least one capital letter, one number, and how frequently it should be rotated.

MFA – Enable MFA for privileged users

  • For extra security, Enable MultiFactor Authentication (MFA) for privileged IAM users, who are allowed access to sensitive resources or APIs.

Role – Use temporary credentials with IAM roles

  • Use roles for workloads instead of creating IAM user and hardcoding the credentials which can compromise the access and are also hard to rotate.
  • Roles have specific permissions and do not have a permanent set of credentials.
  • Roles provide a way to access AWS by relying on dynamically generated & automatically rotated temporary security credentials.
  • Roles  associated with it but dynamically provide temporary credentials that are automatically rotated

Sharing – Delegate using roles

  • Allow users from same AWS account, another AWS account, or externally authenticated users (either through any corporate authentication service or through Google, Facebook etc) to use IAM roles to specify the permissions which can then be assumed by them
  • A role can be defined that specifies what permissions the IAM users in the other account are allowed, and from which AWS accounts the IAM users are allowed to assume the role

Rotation – Rotate credentials regularly

  • Change your own passwords and access keys regularly and enforce it through a strong password policy. So even if a password or access key is compromised without your knowledge, you limit how long the credentials can be used to access your resources
  • Access keys allows creation of 2 active keys at the same time for an user. These can be used to rotate the keys.

Track & Review – Remove unnecessary credentials

  • Remove IAM user and credentials (that is, passwords and access keys) that are not needed.
  • Use the IAM Credential report that lists all IAM users in the account and the status of their various credentials, including passwords, access keys, and MFA devices and usage patterns to figure out what can be removed
  • Passwords and access keys that have not been used recently might be good candidates for removal.

Conditions – Use policy conditions for extra security

  • Define conditions under which IAM policies allow access to a resource.
  • Conditions would help provide finer access control to the AWS services and resources for e.g. access limited to a specific IP range or allowing only encrypted requests for uploads to S3 buckets etc.

Auditing – Monitor activity in the AWS account

  • Enable logging features provided through CloudTrail, S3, CloudFront in AWS to determine the actions users have taken in the account and the resources that were used.
  • Log files show the time and date of actions, the source IP for an action, which actions failed due to inadequate permissions, and more.

Use IAM Access Analyzer

  • IAM Access Analyzer analyzes the services and actions that the IAM roles use, and then generates a least-privilege policy that you can use.
  • Access Analyzer helps preview and analyze public and cross-account access for supported resource types by reviewing the generated findings.
  • IAM Access Analyzer helps to validate the policies created to ensure that they adhere to the IAM policy language (JSON) and IAM best practices.

Use Permissions Boundaries

  • Use IAM Permissions Boundaries to delegate permissions management within an account
  • IAM permissions boundaries help set the maximum permissions that you delegate and that an identity-based policy can grant to an IAM role.
  • A permissions boundary does not grant permissions on its own.

AWS Certification Exam Practice Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. Your organization is preparing for a security assessment of your use of AWS. In preparation for this assessment, which two IAM best practices should you consider implementing? Choose 2 answers
    1. Create individual IAM users for everyone in your organization (May not be needed as can use Roles as well)
    2. Configure MFA on the root account and for privileged IAM users
    3. Assign IAM users and groups configured with policies granting least privilege access
    4. Ensure all users have been assigned and are frequently rotating a password, access ID/secret key, and X.509 certificate (Must be assigned only if using console or through command line)
  2. What are the recommended best practices for IAM? (Choose 3 answers)
    1. Grant least privilege
    2. User the AWS account(root) for regular user
    3. Use Mutli-Factor Authentication (MFA)
    4. Store access key/private key in git
    5. Rotate credentials regularly
  3. Which of the below mentioned options is not a best practice to securely manage the AWS access credentials?
    1. Enable MFA for privileged users
    2. Create individual IAM users
    3. Keep rotating your secure access credentials at regular intervals
    4. Create strong access key and secret access key and attach to the root account
  4. Your CTO is very worried about the security of your AWS account. How best can you prevent hackers from completely hijacking your account?
    1. Use short but complex password on the root account and any administrators.
    2. Use AWS IAM Geo-Lock and disallow anyone from logging in except for in your city.
    3. Use MFA on all users and accounts, especially on the root account. (For increased security, it is recommend to configure MFA to help protect AWS resources)
    4. Don’t write down or remember the root account password after creating the AWS account.
  5. Fill the blanks: ____ helps us track AWS API calls and transitions, ____ helps to understand what resources we have now, and ____ allows auditing credentials and logins.
    1. AWS Config, CloudTrail, IAM Credential Reports
    2. CloudTrail, IAM Credential Reports, AWS Config
    3. CloudTrail, AWS Config, IAM Credential Reports
    4. AWS Config, IAM Credential Reports, CloudTrail


AWS IAM Roles vs Resource Based Policies

AWS IAM Roles vs Resource-Based Policies

AWS allows granting cross-account access to AWS resources, which can be done using IAM Roles or Resource-Based Policies.

IAM Roles

  • Roles can be created to act as a proxy to allow users or services to access resources.
  • Roles support
    • trust policy which helps determine who can access the resources and
    • permission policy which helps to determine what they can access.
  • Users who assume a role temporarily give up their own permissions and instead take on the permissions of the role. The original user permissions are restored when the user exits or stops using the role.
  • Roles can be used to provide access to almost all the AWS resources.
  • Permissions provided to the User through the Role can be further restricted per user by passing an optional policy to the STS request. This policy cannot be used to elevate privileges beyond what the assumed role is allowed to access

Resource-based Policies

  • Resource-based policy allows you to attach a policy directly to the resource you want to share, instead of using a role as a proxy.
  • Resource-based policy specifies the Principal, in the form of a list of AWS account ID numbers, can access that resource and what they can access.
  • Using cross-account access with a resource-based policy, the User still works in the trusted account and does not have to give up their permissions in place of the role permissions.
  • Users can work on the resources from both accounts at the same time and this can be useful for scenarios e.g. copying objects from one bucket to the other bucket in a different AWS account.
  • Resources that you want to share are limited to resources that support resource-based policies
  • Resource-based policies need the trusted account to create users with permissions to be able to access the resources from the trusted account.
  • Only permissions equivalent to, or less than, the permissions granted to your account by the resource owning account can be delegated.

AWS Certification Exam Practice Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. What are the two permission types used by AWS?
    1. Resource-based and Product-based
    2. Product-based and Service-based
    3. Service-based
    4. User-based and Resource-based
  2. What’s the policy used for cross-account access? (Choose 2)
    1. Trust policy
    2. Permissions Policy
    3. Key policy


AWS IAM Access Management

IAM Access Policies

IAM Access Management

  • IAM Access Management is all about Permissions and Policies.
  • Permission help define who has access & what actions can they perform.
  • IAM Policy helps to fine-tune the permissions granted to the policy owner
  • IAM Policy is a document that formally states one or more permissions.
  • Most restrictive Policy always wins
  • IAM Policy is defined in the JSON (JavaScript Object Notation) format

IAM policy basically states “Principal A is allowed or denied (Effect) to perform Action B on Resource C given Conditions D are satisfied”

IAM Access Policies

  • An Entity can be associated with Multiple Policies and a Policy can have multiple statements where each statement in a policy refers to a single permission.
  • If the policy includes multiple statements, a logical OR is applied across the statements at evaluation time. Similarly, if multiple policies are applicable to a request, a logical OR is applied across the policies at evaluation time.
  • Principal can either be specified within the Policy for Resource based policies while for Identity based policies the principal is the user, group, or role to which the policy is attached.

Identity-Based vs Resource-Based Permissions

Identity-based, or IAM permissions

  • Identity-based or IAM permissions are attached to an IAM user, group, or role and specify what the user, group, or role can do.
  • User, group, or the role itself acts as a Principal.
  • IAM permissions can be applied to almost all the AWS services.
  • IAM Policies can either be inline or managed (AWS or Customer).
  • IAM Policy’s current version is 2012-10-17.

Resource-based permissions

  • Resource-based permissions are attached to a resource for e.g. S3, SNS 
  • Resource-based permissions specify both who has access to the resource (Principal) and what actions they can perform on it (Actions)
  • Resource-based policies are inline only, not managed.
  • Resource-based permissions are supported only by some AWS services
  • Resource-based policies can be defined with version 2012-10-17 or 2008-10-17

Managed Policies and Inline Policies

  • Managed policies
    • Managed policies are Standalone policies that can be attached to multiple users, groups, and roles in an AWS account.
    • Managed policies apply only to identities (users, groups, and roles) but not to resources.
    • Managed policies allow reusability
    • Managed policy changes are implemented as versions (limited to 5), an new change to the existing policy creates a new version which is useful to compare the changes and revert back, if needed
    • Managed policies have their own ARN
    • Two types of managed policies:
      • AWS managed policies
        • Managed policies that are created and managed by AWS.
        • AWS maintains and can upgrades these policies for e.g. if a new service is introduced, the changes automatically effects all the existing principals attached to the policy
        • AWS takes care of not breaking the policies for e.g. adding an restriction of removal of permission
        • Managed policies cannot be modified
      • Customer managed policies
        • Managed policies are standalone and custom policies created and administered by you.
        • Customer managed policies allows more precise control over the policies than when using AWS managed policies.
  • Inline policies
    • Inline policies are created and managed by you, and are embedded directly into a single user, group, or role.
    • Deletion of the Entity (User, Group or Role) or Resource deletes the In-Line policy as well

ABAC – Attribute-Based Access Control

  • ABAC – Attribute-based access control is an authorization strategy that defines permissions based on attributes called tags.
  • ABAC policies can be designed to allow operations when the principal’s tag matches the resource tag.
  • ABAC is helpful in environments that are growing rapidly and help with situations where policy management becomes cumbersome.
  • ABAC policies are easier to manage as different policies for different job functions need not be created.
  • Complements RBAC for granular permissions, with RBAC allowing access to only specific resources and ABAC can allow actions on all resources, but only if the resource tag matches the principal’s tag.
  • ABAC can help use employee attributes from the corporate directory with federation where attributes are applied to their resulting principal.

IAM Permissions Boundaries

  • Permissions boundary allows using a managed policy to set the maximum permissions that an identity-based policy can grant to an IAM entity.
  • Permissions boundary allows it to perform only the actions that are allowed by both its identity-based policies and its permissions boundaries.
  • Permissions boundary supports both the AWS-managed policy and the customer-managed policy to set the boundary for an IAM entity.
  • Permissions boundary can be applied to an IAM entity (user or role ) but is not supported for IAM Group.
  • Permissions boundary does not grant permissions on its own.

IAM Policy Simulator

  • IAM Policy Simulator helps test and troubleshoot IAM and resource-based policies
  • IAM Policy Simulator can help test the following ways:-
    • Test IAM based policies. If multiple policies are attached, you can test all the policies or select individual policies to test. You can test which actions are allowed or denied by the selected policies for specific resources.
    • Test Resource based policies. However, Resource-based policies cannot be tested standalone and have to be attached to the Resource
    • Test new IAM policies that are not yet attached to a user, group, or role by typing or copying them into the simulator. These are used only in the simulation and are not saved.
    • Test the policies with selected services, actions, and resources
    • Simulate real-world scenarios by providing context keys, such as an IP address or date, that are included in Condition elements in the policies being tested.
    • Identify which specific statement in a policy results in allowing or denying access to a particular resource or action.
  • IAM Policy Simulator does not make an actual AWS service request and hence does not make unwanted changes to the AWS live environment
  • IAM Policy Simulator just reports the result Allowed or Denied
  • IAM Policy Simulator allows to you modify the policy and test. These changes are not propagated to the actual policies attached to the entities
  • Introductory Video for Policy Simulator

IAM Policy Evaluation

When determining if permission is allowed, the hierarchy is followed

IAM Permission Policy Evaluation

  1. Decision allows starts with Deny.
  2. IAM combines and evaluates all the policies.
  3. Explicit Deny
    • First IAM checks for an explicit denial policy.
    • Explicit Deny overrides everything and if something is explicitly denied it can never be allowed.
  4. Explicit Allow
    • If one does not exist, it then checks for an explicit allow policy.
    • For granting the User any permission, the permission must be explicitly allowed
  5. Implicit Deny
    • If neither an explicit deny nor explicit allow policy exists, it reverts to the default: implicit deny.
    • All permissions are implicity denied by default

IAM Policy Variables

  • Policy variables provide a feature to specify placeholders in a policy.
  • When the policy is evaluated, the policy variables are replaced with values that come from the request itself
  • Policy variables allow a single policy to be applied to a group of users to control access for e.g. all user having access to S3 bucket folder with their name only
  • Policy variable is marked using a $ prefix followed by a pair of curly braces ({ }). Inside the ${ } characters, with the name of the value from the request that you want to use in the policy
  • Policy variables work only with policies defined with Version 2012-10-17
  • Policy variables can only be used in the Resource element and in string comparisons in the Condition element
  • Policy variables are case sensitive and include variables like aws:username, aws:userid, aws:SourceIp, aws:CurrentTime etc.

AWS Certification Exam Practice Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. IAM’s Policy Evaluation Logic always starts with a default ____________ for every request, except for those that use the AWS account’s root security credentials b
    1. Permit
    2. Deny
    3. Cancel
  2. An organization has created 10 IAM users. The organization wants each of the IAM users to have access to a separate DynamoDB table. All the users are added to the same group and the organization wants to setup a group level policy for this. How can the organization achieve this?
    1. Define the group policy and add a condition which allows the access based on the IAM name
    2. Create a DynamoDB table with the same name as the IAM user name and define the policy rule which grants access based on the DynamoDB ARN using a variable
    3. Create a separate DynamoDB database for each user and configure a policy in the group based on the DB variable
    4. It is not possible to have a group level policy which allows different IAM users to different DynamoDB Tables
  3. An organization has setup multiple IAM users. The organization wants that each IAM user accesses the IAM console only within the organization and not from outside. How can it achieve this?
    1. Create an IAM policy with the security group and use that security group for AWS console login
    2. Create an IAM policy with a condition which denies access when the IP address range is not from the organization
    3. Configure the EC2 instance security group which allows traffic only from the organization’s IP range
    4. Create an IAM policy with VPC and allow a secure gateway between the organization and AWS Console
  4. Can I attach more than one policy to a particular entity?
    1. Yes always
    2. Only if within GovCloud
    3. No
    4. Only if within VPC
  5. A __________ is a document that provides a formal statement of one or more permissions.
    1. policy
    2. permission
    3. Role
    4. resource
  6. A __________ is the concept of allowing (or disallowing) an entity such as a user, group, or role some type of access to one or more resources.
    1. user
    2. AWS Account
    3. resource
    4. permission
  7. True or False: When using IAM to control access to your RDS resources, the key names that can be used are case sensitive. For example, aws:CurrentTime is NOT equivalent to AWS:currenttime.
    1. TRUE
    2. FALSE (Refer link)
  8. A user has set an IAM policy where it allows all requests if a request from IP Another policy allows all the requests between 5 PM to 7 PM. What will happen when a user is requesting access from IP at 6 PM?
    1. IAM will throw an error for policy conflict
    2. It is not possible to set a policy based on the time or IP
    3. It will deny access
    4. It will allow access
  9. Which of the following are correct statements with policy evaluation logic in AWS Identity and Access Management? Choose 2 answers.
    1. By default, all requests are denied
    2. An explicit allow overrides an explicit deny
    3. An explicit allow overrides default deny
    4. An explicit deny does not override an explicit allow
    5. By default, all request are allowed
  10. A web design company currently runs several FTP servers that their 250 customers use to upload and download large graphic files. They wish to move this system to AWS to make it more scalable, but they wish to maintain customer privacy and keep costs to a minimum. What AWS architecture would you recommend? [PROFESSIONAL]
    1. Ask their customers to use an S3 client instead of an FTP client. Create a single S3 bucket. Create an IAM user for each customer. Put the IAM Users in a Group that has an IAM policy that permits access to subdirectories within the bucket via use of the ‘username’ Policy variable.
    2. Create a single S3 bucket with Reduced Redundancy Storage turned on and ask their customers to use an S3 client instead of an FTP client. Create a bucket for each customer with a Bucket Policy that permits access only to that one customer. (Creating bucket for each user is not a scalable model, also 100 buckets are a limit earlier without extending which has since changed link)
    3. Create an auto-scaling group of FTP servers with a scaling policy to automatically scale-in when minimum network traffic on the auto-scaling group is below a given threshold. Load a central list of ftp users from S3 as part of the user Data startup script on each Instance (Expensive)
    4. Create a single S3 bucket with Requester Pays turned on and ask their customers to use an S3 client instead of an FTP client. Create a bucket tor each customer with a Bucket Policy that permits access only to that one customer. (Creating bucket for each user is not a scalable model, also 100 buckets are a limit earlier without extending which has since changed link)

Google Cloud Identity Services Cheat Sheet

Identity & Access Management – IAM

  • administrators authorize who can take what action on which resources
  • IAM Member can be a Google Account (for end users), a service account (for apps and virtual machines), a Google group, or a Google Workspace or Cloud Identity domain that can access a resource.
  • IAM Role is a collection of permissions granted to authenticated members.
  • supports 3 kinds of roles
    • Primitive roles – board level of access
    • Predefined roles – finer-grained granular access control
    • Custom roles – tailored permissions when predefined roles don’t meet the needs.
  • Best practice is to use Predefined over primitive roles
  • IAM Policy binds one or more members to a role.
  • IAM policy can be set at any level in the resource hierarchy:  organization level,  folder level, the project level, or the resource level.
  • IAM Policy inheritance is transitive and resources inherit the policies of all of their parent resources.
  • Effective policy for a resource is the union of the policy set on that resource and the policies inherited from higher up in the hierarchy.
  • Service account is a special kind of account used by an application or a virtual machine (VM) instance, not a person.
  • Access Scopes are the legacy method of specifying permissions for the instance for default service accounts
  • Best practice is to set the full cloud-platform access scope on the instance, then securely limit the service account’s access using IAM roles.
  • Delegate responsibility with groups (instead of individual users) and service accounts (for server-to-server interactions)

Cloud Identity

  • Cloud Identity is an Identity as a Service (IDaaS) solution that helps centrally manage the users and groups.
  • configured to federate identities between Google and other identity providers, such as Active Directory and Azure Active Directory
  • Cloud Identity and Google Workspace support Security Assertion Markup Language (SAML) 2.0 for single sign-on  with authentication performed by an external identity provider (IdP)
  • With SAML,  Cloud Identity or Google Workspace acts as a service provider that trusts the SAML IdP to verify a user’s identity on its behalf.
  • Google Cloud Directory Sync – GCDS implements the synchronization process between external IdP

Cloud Billing

  • Google Cloud Billing defines billing accounts linked to Google Cloud Projects to determine who pays for a given set of Google Cloud resources.
  • To move the project to a different billing account, you must be a billing administrator and the project owner.
  • To link a project to a billing account, you must be a Billing Account Administrator or Billing Account User on the billing account OR Project Billing Manager on the project
  • Cloud Billing budgets can be created to monitor all of the Google Cloud charges in one place and configure alerts
  • supports BigQuery export with detailed Google Cloud billing data (such as usage, cost estimates, and pricing data) automatically throughout the day to a specified BigQuery dataset
  • Google Cloud billing data is not added retroactively to BigQuery, so the data before export is enabled will not be visible.