I was in the audience when Amazon announced the AWS Secrets Manager at the AWS Summit San Francisco. My first thought was that we already have a way to store secrets in SSM Parameter Store. In fact, I tweeted:
“Just as we were all working out the details of using SSM Parameter Store to manage our secrets…
Another tool to help build securely (looking forward to learning about it).
#AWSsummit San Francisco” – @esh 2018-04-04 11:10
When I learned the AWS Secrets Manager pricing plan, my questions deepened.
So, I started poring over the AWS Secrets Manager documentation and slowly strarted to gain possible enlightenment.
I have archived below three stream of consciousness threads that I originally posted to Twitter.
After reading the new AWS Secrets Manager docs, it looks like there is a lot of value in the work Amazon has invested into the design of rotating secrets.
There are a number of different ways systems support secrets, and various failure scenarios that must be accounted for.
Though RDS secret rotation support is built in to AWS Secrets Manager, customers are going to find more value in the ability to plug in custom code to rotate secrets in any service–using AWS Lambda, naturally.
Customers write the code that performs the proper steps, and AWS Secrets Manager will drive the steps.
It almost looks like we could take the secret rotation framework design and develop AWS Step Functions and CloudWatch Events Schedule to drive rotation for secrets in SSM Parameter Store,
but for such a critical piece of security infrastructure execution, it makes sense to lean on Amazon to maintain this part and drive the rotation steps reliably.
There are ways to create IAM policies that are fine-tuned with just the AWS Secrets Manager permissions needed, including conditions on custom tags on each secret.
When designing AWS Secrets Manager, I suspect there were discussions inside Amazon about whether ASM itself should perform the steps to move the current/pending/previous version labels around during secret rotation, to reduce the risk of customer code doing this incorrectly.
I think this may have required giving the ASM service too much permission to manipulate the customer’s secrets, so the decision seems right to keep this with the customer’s AWS Lambda function, even though there is some added complexity in development.
The AWS Secrets Manager documentation is impressively clear for creating custom AWS Lambda functions for secret rotation, especially for how complex the various scenarios can be.
Here’s a link to the AWS Secrets Manager Use Guide. https://docs.aws.amazon.com/secretsmanager/latest/userguide/intro.html
Thoughts 2: Rotating Secrets Frequently Is Important
I’m starting to understand that it’s “AWS Secrets Manager” not “AWS Secrets Store”, and that the biggest part of that management seem to be the automated, transparent, reliable secret rotation.
Now that I can see a smooth path to regular secret rotation with AWS Secrets Manager, I’m starting to feel like I’ve been living in primitive times letting my database passwords sit at the same value for months (ok, years).