Adding user in AWS without access to IAM and billing - amazon-web-services

I am looking to add a user in AWS. I have a group with supportUser policy.
The thing is, he can create users and change passwords.
With supportUser policy, he is not able to view any payment information, billing or anything regarding the account.
I am looking for a policy that would only allow him to create a EC2 container, S3 storage and a database. Nothing more. Is there a way to achieve this?

AWS gives you options to create your own fine-grained policies or you can simply use managed policies. Managed policies provide a gentler introduction because AWS has provided curated policies for you. Managed policies are also updated periodically to incorporate new function or new services, as relevant to each specific managed policy.
See AWS managed policies for job functions or, more generally, AWS managed policies.
The simplest managed policies for your use case are probably:
AmazonEC2FullAccess
AmazonRDSFullAccess
AmazonS3FullAccess
Important note: each of these policies grants the user significant permissions over all EC2, RDS, and S3 resources so you may find them too permissive for your use case.
If you want more control then write your own policies. Start at Policies and permissions in IAM. You can also copy/paste the contents of a managed policy and then edit it down to just the permissions you want, and constrained to the resources that you want (e.g. to specific, named S3 buckets).

Related

AWS s3 bucket effective permissions

Is there an easy way to see what are the effective access permissions for a specific bucket? To be more specific about the environment, access to buckets is granted through identity policies, there are more than 170 IAM roles and users and 1000+ policies (not all of them are attached to IAM role or user). I need to see who has the s3:GetObject, s3:PutObject and s3:DeleteObject permission on a specific bucket. Is there some tool that can give me that kind of report? I can write a script that goes through all roles, policies attached to them, pulls out statements that contain specific bucket and then I can cross reference allows and denys, but I'm sure there is some smarter way of doing this.
I am not aware of any better way than you described. You can export your IAM settings (unless you already have them in CloudFormation or CDK scripts) as described at https://aws.amazon.com/blogs/security/a-simple-way-to-export-your-iam-settings/.
Then you can scan (manually or programatically) for policies of interest and to what users or roles are they attached.
From Using Access Analyzer for S3 - Amazon Simple Storage Service:
Access Analyzer for S3 alerts you to S3 buckets that are configured to allow access to anyone on the internet or other AWS accounts, including AWS accounts outside of your organization. For each public or shared bucket, you receive findings into the source and level of public or shared access. For example, Access Analyzer for S3 might show that a bucket has read or write access provided through a bucket access control list (ACL), a bucket policy, or an access point policy. Armed with this knowledge, you can take immediate and precise corrective action to restore your bucket access to what you intended.

IAM S3 Service Role Use Case

I am currently still learning IAM role. As an example, I was able to create EC2 type role and attach the S3 Full Access Control policy. In that case, my EC2 instances can access S3 once the role is attached. Fairly easy to understand.
What is a use case if we select S3 as the type of trusted entity? From my understanding, the access to S3 is usually controlled by the policy. How would S3 service as trusted entity assume the role and what kind of policies could be attached to this role? Just wondering if someone could give me a use case for this. Thanks.
When you add a trusted entity to an IAM role that service is granted the ability to assume the IAM role.
For S3 an example of when this needs to happen is when you want to enable replication, you grant the S3 service the ability to retrieve items from a bucket and put them in another bucket.
For more information on this specific use case take a look at the Setting up permissions for replication page.

AWS Which IAM Role For S3 Presigned URL

I am deploying a server program in an ec2 instance which needs to be able to create pre-signed urls for s3. So far I've had my AWS credentials in environment variables for testing, but I would like to switch to the IAM Role strategy now. However, I am unsure as to which policies the role should have access too. My initial guess is to have AmazonS3FullAccess, but the description says "Provides full access to all buckets via the AWS Management Console" but the ec2 instance will be using the c++ sdk, not the management console. Or is the policy not important, just that it has a policy so it gets credentials somehow?
You're confusing policies and roles.
a policy grants permissions to a user or to a role or to a group.
the difference between a user and a role is subtle, but basically a role is something that's assumed by other services in AWS, like an EC2 instance, while a user is generally just an identity you've created for use in AWS.
The policy description for full access may make mention to the management console, but it grants full access to all buckets whether through the console, the api or an sdk, they're all really the same thing under the hood.
You should not use the fullaccess policy. You could use it as a base to build your real policy, but IAM should always use the least privilege principal, where you only give the permissions that are absolutely required, in this case the role only needs read and possibly list permissions on the specific bucket in question if generating urls for reading, or put permissions if allowing uploads.

Restrict AWS services (policy)

I can't seem to find support for a surprisingly relevant issue. There are 10's of AWS services, so I want an AWS policy that restricts our users to only EC2, RDS and API Gateway. How do I do this? Can I 'deny all' and only endorse these specific services?
When you create a new IAM user, the default is all permissions denied.
If you want all users to have the same permissions, create a group. Assign each user to the group. You can also create multiple groups for different types of users.
Amazon has predefined policies that grant varying levels of permissions for each type of service. Select the policies that apply to your goals to the group(s).
Very easy to implement.
You can also create custom policies that define basically anything that you want. IAM policies range from the simple to the very complex.
You'll need to create Managed IAM policies for all users.
Tutorial
Creating IAM Policies
Example Access policies
You can also create Explicit Deny rules
Test IAM policies

AWS S3 bucket access for role/users- Select Role Type

My intention is simple- to create a role that I can assign to a standard user of my AWS account so that they can read/write to one of my S3 buckets.
I've created a policy to apply to the role and I'm happy with that bit.
The thing I'm a bit confused about is the "Select Role type" screen in the management console (see attached image). I can't work out what I'm supposed to choose at this stage as none of the descriptions seem to apply to the simple thing I'm trying to achieve.
Does anyone have any idea?
I think you are on the wrong path here. Roles are not ACLs for users, but for systems and services.
See: IAM Roles
If you want to grant a user access to some AWS resources you should have a look at the policy section. Either use a pre-build (like AmazonS3ReadOnlyAccess or AmazonS3FullAccess) or define a policy on your own.
You can then assign this policy to a user. If you want to manage multiple users this way, you can also use groups to assign policies to users.