Domain Name Registration Security
ACM.124: Setting up a domain name for our batch job authentication flow
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In my last post, I analyzed the Oktapus attacks in 2022 and we considered some mechanisms for preventing a similar attack on our own system that we are building.
It seems like we are going to need a website to facilitate the authentication workflow I’ve been describing, and that generally starts with a domain name. Since I mentioned in the last post that we want users to be able to easily remember the URL for our batch job administration work flow we’ll want to create something simple and memorable.
I’m thinking about using the following domain — which is a subdomain of 2ndsightlab.com (my top level domain).
Registering a top-level domain name
In order to use that domain I first need to register the top level domain name (2ndsightlab.com) which I’ve already done. The domain I listed above is a subdomain. I can create many subdomains for 2ndsightlab.com. One of the most common subdomains is www (in my case www.2ndsightlab.com) though these days most people drop the www and go straight to the top-level domain (TLD) without the www.
If you want to register a domain name you can do that at AWS:
You could also register a domain through a third party domain name registrar like Google Domains:
NOTE: Google Domains was purchased by SquareSpace since I wrote this. I am not sure how that will work out for security. Square Space does have a bug bounty at least so they do are about security.
One place I cannot recommend for domain name registration is Name Cheap, given that my home network keeps getting hit by rogue traffic from their network.
Why would you want to use one domain name registrar over another?
One of the benefits of using AWS for everything is that you can get all your support in one place. The benefit of registering a domain at a third-party domain name registrar is that Amazon is not in control of your entire stack top to bottom. The other reason you might use one registrar over another is cost — though cheaper registrars might not provide the support you need if your domain is somehow transferred through unauthorized means.
In addition, some registrars will offer TLDs that others do not. For example, one registrar offers domain names that end in .biz or .dev and another offers .cloud, .blog, or .news.
Choosing a top level domain (TLD)
Beware that choosing an odd TLD might get your domain blocked by some security systems. I wrote about the use of odd TLDs by malware here:
Since most legitimate domains do not end in these odd extensions some DNS administrators will reject requests to resolve them, thereby eliminating some potential malware. If you choose one of these odd domain names it may seem cool but requests to visit your web site might be blocked.
There are a lot of other marketing and intellectual property considerations I’m not going to get into here. Before you choose a domain name, you might want to consult with an IP lawyer and marketing person or do some research online at least so you don’t pick a domain name you regret later.
Using a domain name on AWS that is registered somewhere else
If you already have a domain name registered somewhere you can use it on AWS. You just need to configure the domain name properly at the DNS registrar. Consult the documentation for the place where you registered your domain name to figure out how to do that. Generally you will login and provide the “name servers” that will tell the Internet how to get to the server or system that hosts your web site, application, or page.
Here’s how you would configure Google Domains to use AWS DNS Servers:
The following instructions explain how to create a hosted zone in Route 53.
Once you create this hosted zone you can use that information to configure the DNS servers over at Google Domains (or whatever domain name registrar you are using).
Moving or transferring a domain name
You may or may not want to move a domain you registered somewhere else over to AWS. These instructions explain how to set up DNS for an existing domain name with minimal service interruptions.
Note that you could skip the steps to actually move the domain to AWS, but if you want to transfer the domain over to manage it all in once place you can. Note that if you move your domain in the middle of your annual renewal cycle you’ll pay overlapping fees. Additionally, you’ll want to check the cost for the particular domain you’re moving over and make sure AWS supports the TLD.
When you transfer a domain you’ll have to unlock at it at your registrar in order to allow the transfer and follow the instructions both at your existing registrar and on AWS to facilitate the transfer. There may be some downtime depending on how your registrar handles the transfer.
Moving a domain between AWS accounts
You can also transfer domains between AWS accounts. Perhaps you created domains over the years and you want to consolidate them into a single account for simpler management. These instructions will help.
The importance of securing your domain name
Too many people do not understand the importance of securing and protecting their domain names. Sometimes people sign up for hosting providers who register the domain name for the customer. The customer may not understand they do not have access to or control over their own domain name. Make sure you register your own domain name and you know who can transfer it or change the configuration settings.
Here are some of the reasons you want to be careful with domain name registrations and configurations:
- If someone can get ahold of your domain name they can set up a Google Workspace for your domain:
- Conversely, someone could remove the required TXT records for services you have authorized via your DNS configuration services may fail.
- If someone can change where email is directed for your domain they may have access to reset passwords and take over cloud accounts.
- Another DNS related attack I discussed at RSA 2020 is called subdomain takeover. You’ll want to make sure your subdomains point to accurate resources.
- You also don’t want people setting up unauthorized subdomains to or authorizing unwanted services by having access to your DNS configuration.
Now you understand why I always ask customers during a cloud security assessment who has access to the DNS configuration for their domain names. On one Google Cloud Platform (GCP) Security Assessment, the new CISO and staff involved in the assessment had no idea where the domain was registered or who had access to it. Of course they immediately communicated with the executives at the company and addressed that problem when I asked them about it.
Locking down DNS configurations on AWS
You can lock down DNS configurations on AWS by restricting access to Route 53 using IAM and organizational policies. However, you may need certain people to be able to configure some aspects of DNS, but not be able to delete and de-register your domain names.
One strategy would be to put all your domain names in a single account that is accessible by limited people who are responsible for domain name configurations. You might even require that users use a separate login when handling domain names and closing monitor those logins.
Then, create NS records in separate accounts to handle subdomains and web hosting. I’ve used that strategy for penetration testing resources and subdomains associated with cloud security classes. We’ll look at how to automate that in an upcoming post, but first we’ll consider governance for DNS records.
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Teri Radichel | © 2nd Sight Lab 2023
About Teri Radichel:
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