RBAC vs ABAC

Role-Based Access Control (RBAC) and Attribute-Based Access Control (ABAC) are two popular access security models in corporate, government, and other computing environments.

There are several more security models, like Identity-Based Access Control (IBAC), Context-Based Access Control (CBAC), Usage Control, and Zero Trust Access.

Both RBAC and ABAC are mature access control concepts, with early development starting for RBAC in the 1970s and ABAC in the 1980s. RBAC has gained widespread acceptance over the last 25 years due to its simplified management and security enhancements. ABAC was developed to manage security in more complex environments where RBAC could not provide the desired granular control. Both were elevated in 2004 when guidance and implementation were standardized by entities like the National Institute of Standards and Technology (NIST), the American National Standards Institute (ANSI), and the Organization for the Advancement of Structured Information Standards (OASIS).

In a computing environment, access control refers to the rules and practices that enforce the business decision of what employees get access to what resources. Proper access control ensures that only authorized users can access specific resources, such as files, databases, and network devices. It also prevents unauthorized access.

In addition to the selection of an access model like RBAC, ABAC, or Zero Trust, there are several concepts associated with access control:

• Authentication: This is the process of verifying the identity of a user, device, or other entity in a network. Common methods of authentication include passwords, biometrics, and digital certificates.

• Authorization: Once authenticated, authorization determines what an authenticated user is allowed to do. This involves granting or denying permissions to access certain resources or perform specific actions.

• Accounting (or Auditing): This involves tracking the actions of users after they have been authenticated and authorized. It helps in monitoring usage, detecting security breaches, and maintaining records for compliance purposes.

• Access control lists (ACLs): These are tables that define permissions attached to an object. ACLs specify which users or system processes can access objects and what operations they can perform.

• Principle of least privilege: This principle states that users should be granted the minimum level of access—or permissions—necessary to perform their job functions, reducing the risk of unauthorized access.

• Network access control (NAC): NAC solutions enforce policies for devices accessing the network, ensuring that only compliant and authenticated devices can connect.
  

Each of these concepts should be thoroughly considered and documented in the access control section of the cybersecurity or regulatory compliance strategy.

Granular access control takes security a step further, with access permissions defined at a very detailed level. This creates specific and fine-tuned control over resources like specific data fields, functions, or transactions within an application. For example, in a Microsoft SharePoint environment, there may be a document library where all employees can view the documents, but only certain employees can edit the existing files. There can be further access controls within that library that allow another unique set of users to delete documents or create new files and folders. There are many combinations of permissions that can be applied to resources kept in SharePoint. This allows resources to remain secure while also being accessible to authorized users.

As the names indicate, RBAC and ABAC are based on roles and attributes. In the RBAC model, roles are defined based on job functions and responsibilities within the organization. Access to a resource is assigned to a role rather than an individual because it’s easier to move an individual between roles than to recreate permissions when an individual’s role in the company is changed.

Specific roles vary widely depending on the organization’s structure and needs, but there are a few roles, or tiers of roles, that are commonly used:

• Administrator: This role has full access to all system resources and settings. In an IT team, this role might manage user accounts, configure system settings, and maintain security policies. 
• Manager: These employees may need access to resources that help them oversee a team or department. This may include approving employee requests and generating performance reports. 
• User: A network user has access to the resources necessary to perform their specific job functions. They should be allowed to use only the applications and other resources needed for their work. 
• Guest: This person might be a vendor or someone who comes into the corporate office as a visitor for a specific purpose. This role is normally limited access based on their tasks.

Each of these roles may have several variants. Marketing managers, product managers, and finance managers likely need access to different documents and resources to do their work. The same is true for network users, who may fall into operational roles like sales representative, customer service representative, and administrative representative. To meet the needs of these divisions, you need to create one role for each permission set.

The ABAC model shifts the access control decisions to attributes, which provide contextual information that helps determine whether a user should be granted access to a resource. ABAC is more flexible than RBAC and can accommodate a wide range of access control scenarios. Here are the types of attributes commonly used in ABAC, along with their definitions and examples:

•  User attributes: These are related to the user requesting access, and include items like the user’s ID, role, department, security clearance, and location. 
• Resource attributes: Attributes related to the resource being accessed include resource type, resource owner, sensitivity level, and classification. 
• Environment attributes: These attributes belong to the context of the access request. Time of day, date, location, and device type are examples. 
• Action attributes: These are determined by the specific action being requested. For example, read, write, copy, and edit are all action attributes.

In short, assess organizational needs, resources and budget for implementation, and the security and compliance requirements. You should engage stakeholders for this, since they will have information about the different types of access that should be granted. Stakeholders should be brought in early on a project like this, because you will probably be following these steps during implementation:

Implementing RBAC

1. Identify roles: Define all roles within your organization.
2. Define permissions: Specify the access permissions for each role.
3. Assign roles to users: Map users to appropriate roles.
4. Choose a system: Select an RBAC-capable access management system.
5. Configure and monitor: Set up roles and permissions, then regularly review and update them. 

Implementing ABAC

1. Identify attributes: Define user, resource, and environmental attributes.
2. Define policies: Create access control policies based on attributes.
3. Choose a system: Select an ABAC-capable access management system.
4. Configure and test: Set up attributes and policies, continuously test and monitor their effectiveness.

Implementing a Hybrid Approach

1. Implement RBAC foundation: Start by setting up an RBAC framework.
2. Identify additional attributes: Define attributes for more granular control.
3. Develop hybrid policies: Create policies that combine roles and attributes.
4. Choose a hybrid system: Select a system that supports both RBAC and ABAC.
5. Configure, monitor, and update: Set up roles and attributes, then regularly review and update policies.

As you can see, the stakeholders are necessary for most of the decisions in the first few steps.

Zero Trust Access is often preferred to RBAC and ABAC for these common reasons:

Security

•  Assumption of breach: ZTA operates on the principle of “never trust, always verify,” assuming that threats can originate from both inside and outside the network. This contrasts with RBAC and ABAC, which may implicitly trust internal users or devices. 
• Continuous verification: Access requests are continuously authenticated, authorized, and encrypted. Unlike RBAC and ABAC, which may grant access based on a one-time verification, ZTA ensures that access is re-evaluated at every step. 
• Minimized attack surface: By segmenting the network into smaller, isolated segments (micro-segmentation), ZTA reduces the potential damage of a breach, limiting lateral movement by attackers.

Granular control and flexibility

• Context-aware decision making: ZTA considers a wide range of factors in real-time, such as user identity, device health, location, and behavior patterns. While ABAC also uses attributes, ZTA combines these with continuous monitoring and dynamic policies for more nuanced decisions.
• Dynamic access adjustments: ZTA can dynamically adjust access based on current risk assessments and threat intelligence, providing more adaptive security compared to the static nature of RBAC and even the relatively static policies in ABAC. 

Adaptability to modern threats

• Resistance to insider threats: ZTA does not implicitly trust any user or device, significantly mitigating the risk of insider threats. RBAC and ABAC can be more vulnerable if an insider gains unauthorized access.
• Protection against advanced attacks: By continuously validating access requests and enforcing least privilege, ZTA is better equipped to handle sophisticated threats like phishing, malware, and advanced persistent threats (APTs).

Scalability and management

• Centralized policy management: ZTA frameworks often provide centralized policy management, making it easier to enforce consistent security policies across diverse and distributed environments.
• Reduced complexity over time: While initial implementation of ZTA can be complex, it can reduce overall complexity by eliminating the need for extensive role definitions (as in RBAC) and complex attribute configurations (as in ABAC).

Compliance and auditability

• Improved compliance: ZTA’s continuous monitoring and logging capabilities enhance compliance with regulatory requirements by providing detailed records of access requests and decisions. 
• Audit readiness: The detailed logs and real-time monitoring in ZTA facilitate easier and more accurate audits compared to traditional access control methods. 

Zero Trust Access offers a robust security framework, adaptability to changing threat landscapes, and ability to provide granular and context-aware access controls. While it may require a more complex initial setup, the long-term benefits in terms of security and compliance make it a highly effective access control model for modern organizations.