When it comes to APIs, access control is an incredibly important part of ensuring that your APIs are as secure and properly controlled as possible. In this context, one of the most effective methods that has arisen is role-based access control (RBAC), a security practice that segments access to digital systems based on roles.

In this piece, we’ll take a deeper look at RBAC to see what it is, how it works, and how it can secure your applications and APIs. We’ll also compare RBAC to some derivative and related concepts in access control, and isolate why RBAC has become so ubiquitous for API providers.

What Is RBAC?

RBAC is an approach to securing access based upon roles rather than upon individuals. In essence, you define a specific role that a user or client can have, and then you define what that role can actually access through a specific policy.

Systems that use RBAC typically adopt roles aligned against job function — for instance, sales rep, engineer, or admin. Then the roles are assigned specific permissions for resources, such as read, write, or delete. Finally, users may be assigned one or more roles based on their responsibilities and need for access.

Using RBAC in API Security

RBAC is commonly applied within API security. For instance, you might have an ecommerce API that handles payment processing as well as data for customers to facilitate shipping and customer service processes. A frontline representative may need access to read and write customer and order status data, but they may not need access to stored payment information.

In the same ecommerce API scenario, a compliance auditor will need read access to the server storing payment details, but certainly does not need access to general customer data. A security specialist may need access to the servers hosting this data, but not the data itself, and as such, their role will be much more restricted. In this way, you can segment out access by role, rather than by individual access standards or limitations.

Benefits of RBAC

Role-based access control unlocks some major benefits for organizations. Firstly, RBAC drastically simplifies the management of access and user rights. You can bundle users together into classes of access, reducing the total number of distinct user access profiles that you need to manage. Using roles, you can take a company of 200 workers and distill their access tiers into 9 or 10 distinct roles, reducing overall management complexity significantly.

This also results in reduced risk through soft enforcement of the principle of least privilege. By restricting access only to those roles that are deemed necessary for the task, you create a more secure environment by limiting your security risk surface area.

Implementing least privilege by standardizing roles also makes this system far easier to scale as roles and user profiles change. Updates can cascade, meaning that instead of changing 20 users when their role changes, you can update the role itself, and any user with that role will automatically be updated to the new standard.

Finally, this approach to security makes compliance easier to ensure and test. RBAC can help you see at a glance the current state of your identity and access management, and can help constrain drift in access rights that often plague non-RBAC systems.

Drawbacks of RBAC

While RBAC comes with some major benefits, it’s not without its drawbacks. RBAC falls short when systems become dynamic, multi-tenanted, and context-heavy — in these realities, RBAC can become too rigid.

With RBAC, access decisions are made based solely on predefined roles, and as such, it can’t account for things like dynamic resource ownership or environmental shifts that might require updating roles. In API terms, this means you can quickly run into cases where admin or editor is too coarse-grained, causing teams to create more and more roles, causing a problem known as role explosion.

RBAC also struggles significantly with least-privilege enforcement. Because roles are status bundles of permissions, they tend to accumulate access over time, ironically undermining the very reason RBAC was created in the first place. Add to that issues with workload identities, which cause awkward abstractions, poor support for multi-tenancy ownership models, and complexity explosion resulting from over-simplified role alignments, and you get a system that is great for small or stable systems, but breaks under complexity over time.

Evolving RBAC: Fine-Grained Access Control

One variant that you often see in these conversations is something called granular role-based access control (G-RBAC). This approach is very similar to the more generalized RBAC, but instead of having mega groups, you focus on having smaller groups that control access based on the resource itself.

For instance, say you want a specific dashboard to be viewable by anyone who has the dashboard access role, regardless of their job, and as such, you can use both job roles as well as access type roles.

This does give you far better control over both resource and user access paradigms. Still, it does make for a much more complex security environment — and as such, you should consider the tradeoff between a general RBAC approach and a more specific G-RBAC approach.

Alternative Evolutions: ABAC and PBAC

Attribute-based access control (ABAC) and policy-based access control (PBAC) are two modern models that extend and generalize RBAC to resolve some of its drawbacks.

ABAC moves beyond roles by using attributes as the sole definition of access at the time of request. Attributes describe everything — the user, the resource, the action, even the environment. When a request is made, the attributes of all the elements are considered, and a decision for access is made. For instance, “if a user belongs to finance, the resource is classified as finance and internal, and the request is made during normal working hours for the location the request is being made from, approve the request — otherwise deny.”

The problem with ABAC is that there’s no centralized authority for these policies outside of the attributes, and when you need more centralized control, you need a central store for the policies themselves. That’s where PBAC comes into play. With PBAC, access decisions are made using a central store of defined policies that can use roles, attributes, contextual signals, environment state, and even risk heuristics. These policies can be centrally stored, validated, and orchestrated, giving you the ability to formalise access control while managing complexity at scale.

APIs and Access Control

All three of these models — RBAC, ABAC, and PBAC — show up often in the API space, typically via an identity solution using security standards like OAuth 2.0, OpenID Connect, and mTLS. With ABAC, the API evaluates attributes in the request context. PBAC, on the other hand, has to reach out to a central policy store and processor to validate access.

Generally speaking, these solutions move from least complex to most complex, from RBAC to ABAC and to PBAC. But with this complexity, you also see an increase in capability and a rise in support for complex access schemes.

In practical terms, actually implementing RBAC requires some legwork. Firstly, you need to audit your resources to understand what you’re actually securing. Once you have a solid hold on this, you’ll need to plan out your user roles and what specific permissions they’ll need to work within that role. With this base work done, you can start the technical implementation.

The technical side of this is less prescriptive and will ultimately come down to how you handle access control more generally. At its most basic, you can use database controls to restrict access to specific roles and make these roles mapped to RBAC identities.

In a more complex form, you can use middleware solutions that effectively act like authorization servers, requesting tokens or role validation from the user to validate that they belong to the class that can access this resource. Another approach, using a JWT with claims, allows you to pass this validation alongside the user request itself, preventing the need to repeatedly query some auth server or database for permissions.

RBAC is less concerned with the technical how of implementation as much as the conceptual planning of roles, and as such, it’s more technically permissive than other authorization solutions that may prescriptively require a specific solution for mapping and validation.

The Evolving Demand for Access Control

While role-based access control, ABAC, and PBAC are strong solutions for general API security considerations, there are other burgeoning standards — especially in the machine learning and artificial intelligence space. Solutions like SPIFFE/SPIRE and decentralized identity management are offering new modalities for securing and attesting workloads, requests, and flows.

As the demand for more complex access control mounts in the post-AI world, new solutions will be needed to properly secure these systems. Accordingly, while a solid understanding of these current modalities is important, you must also be aware that new evolutions are on the horizon — and that learning RBAC, ABAC, and PBAC is the first step in establishing a secure future for APIs.