The BeyondCorp papers

Google’s BeyondCorp effort would probably be what we would now call Zero Trust, although I am surprised by how little name recognition BeyondCorp has when I talk to security people about Zero Trust. Perhaps there are subtle differences between the two, but if there are they aren’t obvious to me. I find myself reading the relevant Usenix papers for BeyondCorp, so I figure I’ll post a summary of what I got from each paper here.

The earliest of these papers are quite old now (2014), especially for something the rest of the industry is only starting to talk a lot about at the moment. I wonder if there is a viable business model in watching what papers megacorps like Google publish, and the implementing them as commercialized products before the rest of the market catches on?

Either way, here’s a summary of the various papers from the perspective of an interested bystander…

BeyondCorp: a new approach to enterprise security is an introductory paper that introduces the idea of what we would now call Zero Trust networks. That is, that the internal corporate network is not categorized as especially trusted, but instead serves as an access mechanism to services which define their own trust of an end user. This trust is enforced by access gateways, and derived from metrics such as how recently OS updates have been installed on the requesting device. This is a good introduction to the concept, especially given its age.

BeyondCorp: design to deployment at Google — unfortunately this paper was less useful I think. It is higher level than the first paper, and provides fewer actionable insights for someone thinking of implementing Zero Trust.

BeyondCorp: the access proxy describes the high level architecture of the access proxy, which is the frontend which takes requests from clients and authenticates / authorizes them before passing them onto the protected services. There aren’t a lot of surprises here, but it is a good overview of what you might encounter along the way (non-HTTP protocols requiring a client side helper for example).

Migrating to BeyondCorp: Maintaining Productivity While Improving Security is a discussion of the process of transitioning the Google network to the new zero trust access methodology while not breaking users’ ability to get things done. This was implemented by partitioning the problem space into smaller more tractable problems, and then transitioning clients to the new non-priviledged VLAN as these problems were solved. A key component of this was an enterprise wide rollout of 802.1x to ensure device identity was well understood. This paper is largely descriptive — while it might provide inspiration to other implementations, it does not provide a complete roadmap, largely because every organization’s legacy applications will differ.

That said, one interesting idea is that the network rules to control traffic were implemented in two places — in the network layer for the new VLAN, but also in an iptables implementation on client machines. This meant that it was easy to add clients in test mode (with the local implementation), but turn it off again if things didn’t work out. It also meant that they could add enforcement in locations where the new VLAN had not yet been deployed.

Another interesting idea is the provisioning of micro-VPNs for harder to convert applications such as those requiring non-HTTP access to network resources. This looks to my modern eyes as a lot like what tailscale does — exposing a single application via a micro-VPN accessed from the client routing table.

BeyondCorp: The User Experience details the gradual reduction in the demand for “traditional” VPN connectivity as users were moved to BeyondCorp, even as users initially expected a more traditional approach. It covers other user support scenarios as well, but most of them are quite Google-specific (for example their loaner laptop program).

BeyondCorp: Building a Healthy Fleet is the final paper in the series and discusses defining the threats your are mitigating by undertaking a Zero Trust approach to network security. In the case of BeyondCorp a large amount of the benefit is derived from enforcing regular updates on the user endpoint fleet, as well as controlling who can access what service based on their business needs.

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