RavenDB Security ReportMan in the middle for customer domains
The RavenDB Security Report most significant finding is something that cannot be fixed. Let me try to explain the core of this issue.
We want RavenDB to be secured, and we have chosen to use the well known (and trusted) TLS infrastructure. This means that we can use HTTPS, client certificate authentication and TLS 1.2. Basically, this means that we have a very high degree security and we use a common (and trusted) methods for both trust and encryption on the wire. That does leave us with the problem of where to get the certificates from. Browsers has been tightening security for a while now, and the kind of alerts you get for self signed certificates are too scary to show by default.
So we need a solution that will be trusted. One option is to generate and install a root certificate when installing RavenDB. I don’t really like this option, to start with, installing a root certificate seems like an invasive action, even if it was generated locally. But this doesn’t solve the problem of accessing the server remotely. The root certificate will be installed on the server, not the client. So that isn’t a good option for us.
Enter Let’s Encrypt and the ability to generate certificates for free. That is a perfect solution for the problem. It is possible to generate them during installation, it is trusted by all major browsers and voila, we are there. Except there is still one issue in place. In order to get the certificate, we need to prove to Let’s Encrypt that we own the domain. But we can’t expect every user to configure DNS or setup routing properly during installation. So instead of making the user do the work, the automatic Let’s Encrypt installation is going to do that using a domain that RavenDB controls (ravendb.community, development.run, ravendb.run, etc). As part of the installation, the local RavenDB instance will talk to our cloud API to complete the Let’s Encrypt challenge. Each user gets their own subdomain under one of the root domains we use and the certificate is being generate locally (the cloud API is involved only for setting up the DNS entries).
This is perfect, because it means that you can very easily get a secured cluster (with URLs such as https://a.oren.development.run) which will just work.
However, from the point of view of the customer, there is an issue. The customer doesn’t own these domains, they are owned by Hibernating Rhinos. This means that technically, we can issue additional certificates for the cluster domain and even update the DNS records to point to another server. This is something that we will never do, but it is a concern that should be raised during security reviews. For production usage, we expect operators to use their own certificates and domains to ensure that they have full control of their environment.
This is the only issue in the security review that we couldn’t fix and had to document as a warning to users, because it is too convenient a feature and the expected usage scenario (development and quick setup mode) are not likely to concern themselves with the full blown process of defining DNS and certificates.