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Lock Up Your Customer Accounts, Give Away the Key

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Re: Lock Up Your Customer Accounts, Give Away the Key

#2
There's a reasonable case for including internal actors in one's threat model for larger companies or ones working in extraordinarily sensitive product domains. Most startups probably don't need to prevent the team from being able to read credentials, because that's theatre when they have 15 different ways to get to any secret the company has.

We use Ansible's vault feature to decrypt a few centralized secret files onto machines at deploy time. This lets us commit the encrypted text of the files. (The source of truth for the key is in Trello, IIRC, but it could be anywhere you have to auth in as an employee to view.)

It's modestly annoying (operations like "check what changed in the secret configuration file as a result of a particular commit" are impossible) but seems like a reasonable compromise to ensure that e.g. nobody can insta-create an admin session if they happen to have a copy of our codebase and a working Internet connection.

Secrets are communicated to processes which need them in boring Linux-y ways like "file i/o" and "stuff it into an environment variable that the process has access to." If you're capable of doing file i/o or reading arbitrary memory, we're in trouble. Of course, if you can do either of those on our production infrastructure and also connect to our database, we've already lost, so I don't see too much additional gain in locking down our database password.

If you're starting from the position "I have a Rails app which has passwords in cleartext in database.yml" this is an easy thing to roll out incrementally: move the password from database.yml to ENV['RAILS_DB_PASSWORD'], spend ~5 minutes getting your deployment infrastructure to populate that from an encrypted file (details depend on your deployment infrastructure -- I am liking ansible, a lot, for this), verify it works, then change passwords. Voila; Github no longer knows your database password and your continuous integration system no longer knows your production credentials. One threat down; zero coordination required with any other system you use or any other team at the company. You can standardize on this across your entire deployment or not, your call, and it's exactly as easy to back out of as it was to get started.

Re: Lock Up Your Customer Accounts, Give Away the Key

#3
This article confuses me. The author tears down a strawman argument about running centralized key services ("The expensive solution"), then recommends exactly such a solution in Amazon KMS.

The only plausible way this can make sense to me is if he said "Running your own key service is a pain, use Amazon KMS". But that's a simple service question, probably wouldn't have taken up as much space.

Re: Lock Up Your Customer Accounts, Give Away the Key

#5
Everything here except for the engineers question can also be solved by simply hosting these things yourself. You don't need 3rd party code hosting on Github, just use Gitlab or JIRA. You don't need some external CI service, run your own Jenkins node. Chat and email should also be internal (we use XMPP, a local Mattermost instance would be an alternative) and SSL-only. You can do all of this with basically 1 docker command per install on your own dedicated hardware with a fairly underpowered machine. And this prevents leaking of all sorts of information, not just production database passwords.

Re: Lock Up Your Customer Accounts, Give Away the Key

#6

This article confuses me. The author tears down a strawman argument about running centralized key services ("The expensive solution"), then recommends exactly such a solution in Amazon KMS. The only plausible way this can make sense to me is if he said "Running your own key service is a pain, use Amazon KMS". But that's a simple service question, probably wouldn't have taken up as much space.

Not only that, but everything here except for the engineers question can also be solved by simply hosting these things yourself.

You don't need 3rd party code hosting on Github, just use Gitlab or JIRA. You don't need some external CI service, run your own Jenkins node. Chat and email should also be internal (we use XMPP, a local Mattermost instance would be an alternative) and SSL-only.

You can do all of this with basically 1 docker command per install on your own dedicated hardware with a fairly underpowered machine.

And this prevents leaking of all sorts of information, not just production database passwords. If you don't trust your engineers, you have bigger problems, as another poster pointed out, if they can modify your software to simply report the password back to them, or just login to production and decrypt it, you're dead in the water.

Re: Lock Up Your Customer Accounts, Give Away the Key

#7

This article confuses me. The author tears down a strawman argument about running centralized key services ("The expensive solution"), then recommends exactly such a solution in Amazon KMS. The only plausible way this can make sense to me is if he said "Running your own key service is a pain, use Amazon KMS". But that's a simple service question, probably wouldn't have taken up as much space.

KMS is not a centralized secret database -- it's a hosted Hardware Security Module. There is no way to store your service's secrets in it for later retrieval, unlike the solutions listed in the article. I suppose an argument could be made that it still provides a single point of failure, however the risk level of KMS and the SLA it provides is far lower than what one might encounter by maintaining their own server cluster.

Re: Lock Up Your Customer Accounts, Give Away the Key

#8

The recommended solution is still vulnerable to employee compromise: if they can push software that runs as a trusted role, they can steal any secrets that software has access to.

This is certainly the case, however for an organization implementing best practices for code deployment, such a change would have to be peer-reviewed in the best case, or pushed directly to master with an obvious paper trail in the worst. It wasn't my intention to imply that employing well-designed envelope encryption would shut the door on any possibility of an engineer gaining access to secrets; clearly there's a lot more involved in making that happen. However, this goes a long way to allowing the source of any leaks to be traced should they occur.
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