If You Just Do One Thing Today, Run the AWS IAM Access Analyzer
When it was announced in December last year, AWS called the AWS IAM Access Analyzer “the sort of thing that will improve security for just about everyone that builds on AWS.” Last week, it was expanded to the AWS Organizations level. If you use AWS, use this tool to ensure your access is granted as intended across your accounts.
“IAM” Having Problems
AWS provides robust security and user/role management, but that doesn’t mean you’re protected from the issues that can arise from improperly configured IAM access. Here are a few we’ve seen the most often.
Creating a user when it should have been a role. IAM roles and IAM users can both be assigned policies, but they are intended to be used differently. IAM users should correspond to specific human users, who can be assigned long-term credentials and directly interact with AWS services. IAM roles are sets of capabilities that can be assumed by other entities — for example, third-party software that interacts with your AWS account (hi! 👋). Check out this post for more about roles vs. users.
Assigning a pre-built policy vs. creating a custom policy. There are plenty of pre-built policies — here are a few dozen examples — but you can also create custom policies. The problems arise when, in a hurry to grant access to users, you grant more than necessary, leaving holes. For example, we’ve seen people get frustrated when their users don’t have access to a VM but little insight into why — while it could be that the VM has been terminated or moved to a region the user can’t view, an “easy fix” is to broaden that user’s access.
Leaving regions or resource types open. If an IAM role needs permission to spin EC2 instances up and down, you might grant full EC2 privileges. But if the users with that role only ever use us-east-1 and don’t look around the other regions (why would they?) or keep a close eye on their bill, they may have no idea that some bad actor is bitcoin mining in your account over in us-west-2.
Potential attacks need only an opportunity to get access to your account, and the impact could range from exposing customer data to ransomware to total resource deletion. So it’s important to know what IAM paths are open and whether they’re in use.
Enter the AWS IAM Access Analyzer
The IAM Access Analyzer uses “automated reasoning”, which is a type of mathematical logic, to review your IAM roles, S3 buckets, KMS keys, AWS Lambda functions, and Amazon SQS queues. It’s free to use and straightforward to set up.
Once you set up an analyzer, you will see a list of findings that shows items for you to review and address or dismiss. With the expansion to the organizational level, you can establish your entire organization as a “zone of trust”, so that issues identified are for resources accessible from outside the organization.
The Access Analyzer continuously monitors for new & updated policies, and you can manually re-analyze as well.
3 Things to Go Do Now
If you had time to read this, you probably have time to go set up an analyzer:
- Create an AWS IAM access analyzer for your account or organization
- Review your findings and address any potential issues.
- Check the access you’re granting to any third-party service. For example, ParkMyCloud requests only the minimum permissions needed to do its job. Are you assigning anyone the AWS-provided “ReadOnlyAccess” role? If so, you are sharing far more than is likely needed.
Originally published at www.parkmycloud.com on April 9, 2020.