What You Need to Know About Fine-Grained vs. Coarse-Grained Authorization

4 min read

With the growing importance of cloud-native security and zero-trust approaches to software, questions around the level of access granted to cloud resources have become more critical. Equally important is to understand the value of different authorization strategies. 

In this article, we present an overview of fine-grained and coarse-grained authorization methods. Key takeaways include:

  • Coarse-grained authorization is suited for broader forms of access controls, such as those focused on roles.
  • Fine-grained authorization enables the higher level of specificity that is often required to secure more complex and scalable cloud-native developments.
  • Open Policy Agent (OPA) and Styra Declarative Authorization Service (DAS) help to enable the right level access control while automating policy management and enforcement, allowing for granular access control at scale.

What Is Granular Authorization?

Authorization policies govern who or what can do what in a given system. The amount of specificity in authorization decisions determines the level of granularity involved. More granularity, in other words, refers to a higher level of detail or context required to authorize a particular user or entity in a system or network.

Authorization policies based only on associated roles are generally coarse-grained. However, the greater the number of details and context required, such as location or time of the day, the greater the degree of granularity.

Here’s the key difference:

  • Fine-grained access control is the ability to grant or revoke access to critical systems and data according to multiple conditions. For example, users under a certain role can access service A only if they have spent at least one year with the company. 
  • Coarse-grained access control requires a lower level of specificity in granting or denying access. For example, any user under a particular role (for instance, engineering or people operations) can access service A.

RBAC vs ABAC: What’s the Difference?

While role-based access control (RBAC) is often associated with coarse-grained authorization, attribute-based access control (ABAC) is typically a more fine-grained method, because it enables teams to specify finer details and contextual information around who is allowed to which resources.

Role-Based Access Control (RBAC)

RBAC enables you to assign users to roles, which are then mapped to permissions. You could create a role for admin users and another role for regular users. As a static model, RBAC is easier to manage and configure, but it can be less secure since it gives all users in a certain role the same permissions. 

This method, however, is suited for cases in which multiple layers of conditions are not required. For example, enterprises use roles to provide employees with varying access levels: managers can see the salary information of members of their team, but team members cannot access each other’s salary information. 

Role Explosion Is a Challenge

One of the challenges of coarse-grained authorization is its limited flexibility and scalability. In RBAC models, each role has its own set of permissions. As the number of users or job functions increases, administrations may need to create new roles and permissions that don’t easily fit into their previous mapping — which can add significant complexity to RBAC management at scale. 

As we found in our 2022 Cloud-Native Alignment Report, 64% of developers say that one of the top challenges for cloud-native expansion is setting proper employee controls for IT to manage. As more resources or capabilities are added, managing those roles becomes even more challenging due to role explosion.  

The takeaway: When your organization needs more flexibility and scalability, it needs to move to more granular authorization methods, such as ABAC. As we have discussed, for instance, RBAC is not enough for Kubernetes API security. To learn more, download our white paper.

Attribute-Based Access Control (ABAC)

Attribute-based access control offers teams a greater degree of granularity, as it maps to users’ attributes, which can be much more specific and context-based than roles. For instance, you can assign attributes to users, resources and actions, and then create a fine-grained policy to allow a specific group of users to access certain resources only under a specific time of the day. This type of policy helps ensure that employees don’t access critical information outside work hours.

As you might expect, fine-grained authorization is generally more secure, because it narrows down access. Agility to remove permissions is also crucial to minimize the risk of lateral movement and data leakages. As noted by the 2022 Data Breach Investigation Report, privileged parties can do more damage than outsiders when it comes to the number of records compromised.

On the other hand, the downside of ABAC is that it can be more challenging to manage and configure, because it can require a more complex series of policies that lay out the conditions under which users are granted access to resources and services. 

Want to learn more about fine-grained controls for cloud-native apps? Watch the Styra webinar now.

Summary: Coarse-Grained vs Fine-Grained Access Control 

In highly distributed and heterogeneous cloud architectures, applications have different authorization needs. The choice between fine-grained vs coarse-grained controls ultimately depends on the project at hand. 

Here’s a quick breakdown: 

Coarse-Grained AuthorizationFine-Grained Authorization
Level of granularityLess specificity is taken into account when determining who or what has access to resources Multiple conditions determine access  
FlexibilityStatic authorization model that doesn’t always scale well, as it can lead to role explosionDynamic approach that takes context into account for increased security
Example Role-based access control (RBAC)Attribute-based access control (ABAC)
Use caseUsing employee’s job function to grant or deny access to salary informationAccess to data is limited according to employee’s location, budget managed or working hours 

Still Not Sure Between Fine vs Coarse-Grained Authorization? 

You don’t need to choose between coarse vs fine-grained access control. With Open Policy Agent (OPA) and Styra DAS for cloud-native entitlements, you can implement both RBAC and ABAC mechanisms based on the unique needs of your applications. ​​As a control plane for Open Policy Agent (OPA), Styra DAS helps to enforce authorization at scale because it automates policy management in cloud-native environments.

Sign up for a Styra DAS demo today to see how you can implement fine-grained access controls!

Read More:

Kubernetes Compliance

Microservices Authorization

What is Kubernetes Security

K8s Security Checklist

Cloud native

Entitlement Explosion Repair

Join Styra and PACLabs on April 11 for a webinar exploring how organizations are using Policy as Code for smarter Access Control.

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