We have started initially by defining roles with admin access policy attached. But now we want them to have policy with only specific permissions that are minimum and does not create any issues for using these roles.
Looking at "Access Advisor" tab on each role under AWS IAM console, it gives good amount of information that exactly which AWS services getting used and permission level information only for EC2, IAM, Lambda, and S3 management actions services. But for rest of other AWS services, missing that what specific permission for that particular service is required.
Also not having AWS Organizations master account access as mentioned in this tutorial: Viewing last accessed information for Organizations.
So is there a way I can get the permissions level info for services other than EC2, IAM, Lambda, and S3 management actions?
Thanks.
So is there a way I can get the permissions level info for services other than EC2, IAM, Lambda, and S3 management actions?
Sadly, there is no such way provided by AWS. So basically its try-and-see approach to get what you want. You can try some third party tools, which may be helpful, such as zero-iam, but ultimately, you will need custom solution to match your requirements.
There is also IAM Access Analyzer which is different then Access Advisor. But its also limited to some services only.
I'm creating a serverless app using API Gateway and Lambda. When creating roles for my API. What is best practice, How granular should I get?
Should I create a new role for every resource?
Or every method?
Or for API Gateway and Lambda respectfully?
Its application specific, but the general rule is to follow AWS best practice and grant least privilege permissions for accessing your resources.
Following the AWS best practice, you:
Start with a minimum set of permissions and grant additional permissions as necessary. Doing so is more secure than starting with permissions that are too lenient and then trying to tighten them later.
More specific to your question. API Gateway don't have roles, they have resource policies. They are generally used to specify permissions regarding who/what can invoke your API. I would recommend checking out official AWS examples of such policies and model your policies based on them, which includes how detailed they are: API Gateway resource policy examples
Since in your setup, lambda is going to be accessing your other resources (e.g. S3, DynamoDB) you should specify its permissions to access these resources in its execution role.
If you have several lambda functions having same permission they can reuse the same role. Also if you want to use different roles, you may create IAM custom managed policies which you could attach and reuse across different roles.
I'm totally new to AWS and learning about IAM. I was wondering if there is a way around for an IAM user to check what all permission he/she have? Like as a root user, I created a group of IAM users where they were only allowed to use S3 service but once I logged in as an IAM user, it was showing that I have access to other AWS services as well like running EC2 instances, etc which I reckon shouldn't be the case. Thanks!
No, it isn't possible to "show" which services you have access to use, because the policies can be quite complex (eg permission to access an S3 bucket, but only a particular sub-folder if coming from a given range of IP addresses).
You would need to look the the IAM Policies attached to the IAM User, plus the policies on any IAM Groups they are in. Then, some services like Amazon S3 have additional permissions such as Bucket Policies.
In addition, AWS Organizations can limit the permissions of all users within an AWS Account, so even if a user appears to be granted certain permissions, they might not actually be available for use.
In many situations, you'll only know if you can do something by actually trying it. For example, you might have Read Only permissions, which means you can see resources in the AWS Console, but you would receive an error when you try to change things.
All services are available in the AWS Console, but various parts of the console will only work if you have adequate permission.
Note that there's IAM Policy Simulator from AWS. You can select a service and check if a given user has access to any given action (or all actions relevant to a service)
Background: On Azure (we're in the process of moving from azure to aws), we have everything organized into resources groups. By default no one can do much in the prod subscription(account), but based on the team asking for a provisioned resource, a team member gets stamped as the "owner" of the resource group, which just gives him/her full access to that resource group, and can add/remove other members as they see fit. This allows us to set up a very fine-grained set of access controls where each team ultimately decides whats allowed and not - not based on groups but based on users getting access to resource groups (in which instances and other resources exist).
Now that we're moving to AWS I had hoped to use the SAML integration to provide access (we're running Auth0 in front of AzureAD, but this should be the same for any saml/federated aws setup I think).
My problem is that with SAML AWS doesn't really "see" each individual user - they're not auto-created in IAM at first logon or anything, so the only "security boundary" I have to work with are the groups I send into AWS, which I can assign to IAM roles.
This is a problem, because 1)the user has to select the desired role at login (if member of more than one), and 2)each role setup is a manual task which requires me to configre AzureAD, saml claims in auth0 and finally IAM roles in AWS. The latter is obviously something I can automate, but still.
Here's the core of my problem:
Say that I have 2 EC2 instances in AWS: DB and Web. I have 3 users, AdminPete, DBDave and WebWilson. I'd like to be able to give Pete full access to both instances, while Dave and Wilson gets access to "their own" ec2 instance. As far as I can see, I would have to configure two IAM roles (DB and Web), and require Pete (who has access to both) to choose his role at login. This is a super-simple example, but it doesn't really scale well at all.
I'm curious to hear how you guys are doing access control in aws - my goal is to be able to create a very fine-tuned setup using tags or some other mechanism. The official aws documentation only deals with getting saml configured (which is easy enough), but very little about real-life permissions management.
The core of the problem (imho) is that unlike "regular" iam users, I can't attach an iam policy or a group to a single user when that user is federated - I can only attach the policy to the federated role as a whole.
Any pointers appreciated! At this point I'm considering just not using saml at all for our aws stuff so that we can use fine-grained iam policies to manage permissions in a more flexible manner.
The AWS official site reads role as a collection of permissions and group as a collection of users. But still they look the same to me. You attach policies to groups or roles, and then assign groups or roles to a user. What exactly are the differences between role and group?
Short answer for googlers: you can't assign role to user.
group is a bunch of users with the same policies
role is a preset of policies for service(s)
Users can asume roles according to AWS docs:
Assuming a Role
AWS Groups are the standard groups which you can consider as collection of several users and a user can belong to multiple groups.
AWS IAM Roles are all together different species; they operate like individual users except that they work mostly towards the impersonation style and perform communication with AWS API calls without specifying the credentials.
Given that IAM Roles are little different, I am emphasizing only that. There are several types of IAM Roles like EC2 IAM Roles, Lambda etc. If you consider, you can launch an EC2 instance with an EC2 IAM Role; hence forth any AWS API related communication wouldn't require any AWS Access Key or Secret key for authentication rather can call the APIs directly (however the long answer is - it uses STS and continuously recycles the credentials behind the scenes); the privileges or permissions of what it can do is determined by the IAM Policies attached to the IAM Role.
Lambda IAM Role works exactly the same, except that only Lambda function can use the Lambda IAM Role etc.
Users: End User (Think People).
Groups: A collection of users under one set of permissions (permission as policy). As per IAM standards we create groups with permissions and then assign user to that group.
Role: you create roles and assign them to AWS resource (AWS resource example can be a customer, supplier, contractor, employee, an EC2 instance, some external application outside AWS) but remember you can't assign role to user.
It’s not only users who will login, sometimes applications need access to AWS resources. For example, an EC2 instance might need to access one or more S3 buckets. Then, an IAM role needs to be created and attached to the EC2 instance. That role can be re-used by different EC2 instances.
Remember : Groups are for living. Roles are for non-living.
I think of an AWS Role as a kind of 'sudo', where each AWS Role can temporarily provide a very specific set of elevated privileges, but without needing the elevated credentials. I get the impression that like sudo, AWS Roles try to prevent privileged actions being used accidentally.
I'd be interested to hear if others agree with this analogy.
Please note that Groups are specific to local IAM users, which are not federated, and local IAM user logs do not show who has done the actions (i.e.., multiple people or applications could use the same long-term secret/access keys, and there is no record of which entity used them). If you must use local IAM users, you can place them into IAM Groups. Where this can be especially useful is to serve as a boundary -- you could place a deny policy on the group, restricting access to specific services or actions, and that deny policy will be applied to all users in the Group.
Conversely, roles can be federated, whereas local IAM users are not. You might create an on-premises AD group that serves as a member container, for example, and then the members of that AD group (and only they) can use the role that the AD group correlates to, with whatever allow or deny policies and/or permissions boundaries you've applied to the role. (Here is a link explaining the AWS ADFS federation.)
Importantly, roles allow for temporary session credentials (which is a best security practice), as their session tokens expire after a maximum of 12 hours. Equally importantly, roles do show in the logs which of the AD members with access to use the role actually did the action. You'll find this tacked to the end of the role ARN in the logs (e.g., a user ID). CloudTrail would be one of several services that indicate user activity. This is important from a logging standpoint.
Understanding IAM roles vs IAM groups (IAM indentities) is very important foundational concept . Its important to look at difference between IAM role and IAM user as essentially group is just a bunch of users performing similar functions (eg. group of developers, QA's etc.) Roles are not uniquely associated with one person (user), they can be assumed by user,resource or service who needs it to perform task at that point of time (session). Roles do not provide long-term credentials like password or access keys.
Best practice recommendation is to require workloads to use temporary credentials with IAM roles to access AWS
Please refer to link below for more clarity:
https://docs.aws.amazon.com/IAM/latest/UserGuide/id.html
I was confused all the time about the difference between these two functions.
In short,
Role is like a tag with all the preset policies that can attach on IAM users/groups or AWS services. IAM users share the same account with the account root user (Admin) but with assigned permissions by the root user to use AWS resources within that account.
Therefore, IAM users can directly interact with AWS services; whereas IAM roles cannot make direct requests to AWS services, they are meant to be assumed by authorised entities like an IAM user or an instance. https://aws.amazon.com/iam/faqs/
I had a hard time deciphering the spirit of the given answers..
Here's what I've found:
Groups:
Intended to represent human users created within IAM who need identical policies.
Ex. Dev 1 - Dev 8 are all developers, and all need access to create dev servers.
This is similar to traditional desktop users/groups, but for HUMAN users only.
Roles:
Roles rotate automatic credentials, meaning password input isn't needed for accessing policies.
This makes it good for two things:
Giving permissions to non-humans, such as services / applications.
Ex. EC2 of type A needs access to S3 of type B.
Giving permissions to federated / outside users & groups.
Ex. Contractor A # Outside Company A needs access to your Server A.
Authentication of users & groups are handled by some service, like Azure AD.
Authorizations are then mapped to your IAM role(s), NOT users or groups.
Note: I've used Jumpcloud's Article & AWS's Documentation to gather this information. The terms "Group", "Role", and "User" become overloaded in context to SSO+IdP, and IAM.
Here's an image showing how they map roles. !Need 10 Reputation :(
Aside: There is a way of assigning Roles to normal IAM Users & Groups, but it appears to be bad practice.
Hopefully this provides clarity to the answers above.
Only one IAM Role can be assumed at a time! And there are several
situations which fits exactly this kind of permission.
Read the faq about: How many IAM roles can I assume?
The underlaying tool in use is "Permission" in both of the use cases namely: Group and IAM Role.
Group or IAM Role --> Has Policy --> Policy defines permisions --> Permissions are assigned to a Group or IAM Role.