DevOps

Strengthen Your AWS Security by Protecting App Credentials and Automating EC2 and IAM Key Rotation

by Jake Bennett

Effective information security requires following strong security practices during development. Here are three ways to secure your build pipeline, and the source code to get you started.

Keys


One of the biggest headaches faced by developers and DevOps professionals is the problem of keeping the credentials used in application code secure. It’s just a fact of life. We have code that needs to access network resources like servers and databases, and we have to store these credentials somewhere. Even in the best of circumstances this is a difficult problem to solve, but the messy realities of daily life further compound the issue. Looming deadlines, sprawling technology and employee turnover all conspire against us when we try to keep the build pipeline secure. The result is “credential detritus”: passwords and security keys littered across developer workstations, source control repos, build servers and staging environments.

Use EC2 Instance Profiles

A good strategy for minimizing credential detritus is to reduce the number of credentials that need to be managed in the first place. One effective way to do this in AWS is by using EC2 Instance Profiles. An Instance Profile is an IAM Role that is assigned to an EC2 instance when it’s created. Once this is in-place, any code running on the EC2 instance that makes CLI or SDK calls to AWS resources will be made within the security context of the Instance Profile. This is extremely handy because it means that you don’t need to worry about getting credentials onto the instance when it’s created, and you don’t need to manage them on an ongoing basis—AWS automatically rotates the keys for you. Instead, you can spend your time fine tuning the security policy for the IAM Role to ensure that it has the least amount of privileges to get its job done.

Get Credentials Out of Source Control

EC2 Instance Profiles are a big help, but they won’t completely eliminate the need to manage credentials in your application. There are plenty of non-AWS resources that your code requires access to, and EC2 Instance Profiles won’t help you with those. For these credentials, we need another approach. This starts by making sure that credentials are NEVER stored in source control. A good test I’ve heard is this: if you were forced to push your source code to a public repository on GitHub today, then you should be able to sleep well tonight knowing that no secret credentials would be revealed. How well would you sleep if this happened to you?

The main problem is that source code repositories typically have a wide audience, including people who shouldn’t have access to security credentials. And once you check in those credentials, they’re pretty much up there forever. Moreover, if you use a distributed SCM like Git, then those credentials are stored along with your source code on all of your developers’ machines, further increasing your exposure. The more breadcrumbs you leave lying around, the more likely rats will end up infesting your home. This appears to be what happened in the Ashley Madson hack that took place earlier this year.  Hard-coded credentials stored in source control were implicated as a key factor in the attack. Apparently, their source code was littered with the stuff. Not good.

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