Access control is the practice of ensuring only authorized users, using trusted devices, receive the appropriate level of access to specific resources at the right time. It prevents unauthorised users from entering physical spaces or viewing digital assets, while giving authorised users fast, safe access to do their jobs. This guide explains the main types of access control models, the systems that implement them, and best practices to avoid potential security gaps.
What Are Access Control Systems
Access control systems identify a user, authenticate the user’s identity, evaluate policies and access rules, then grant access or deny access to the requested resource. These security measures protect sensitive information and help maintain confidentiality, integrity and availability for both enterprises and small businesses.
Core components and functions:
Identification: a unique user identity, device identity, or visitor identity
Authentication: passwords, PINs, cards, mobile credentials, biometrics, and multi factor authentication
Authorisation: policy evaluation that sets access rights and permissions for authorised users
Audit: detailed logs of access events to support investigations, reviews and compliance
Provisioning: creating, changing and removing accounts and permissions, ideally with automation
Systems in practice:
Physical Access Control Systems regulate entry to doors, cabinets, and restricted areas
Digital Access Controls regulate entry to applications, files, APIs and data sets
Cloud Based Access Control Systems centralise policy and management on a hosted platform
Biometric Access Control Systems grant access using fingerprints, facial recognition, or iris scans. Biometric access control systems use unique physical characteristics such as fingerprints or facial recognition to grant access.
Visitor Management Systems issue temporary credentials and track non employees on site
Key Concepts That Make Access Control Work
Every access decision evaluates a subject, an object, a set of permissions and access privileges a policy.
Access Rights And Permissions: read, write, execute, approve, unlock, arm, disarm
Access Control Lists: tables that specify which users or groups may perform which actions on a resource
Access Policies And Access Rules: written conditions that govern who may gain access and under what circumstances
Least Privilege: grant the minimum access necessary and remove it when no longer needed
Separation Of Duties: split risky actions so no single person can complete them alone
Physical Versus Logical: physical access controls protect spaces and assets, while logical access control protects systems and data
Discretionary Access Control (DAC)
Discretionary access control allows the data owner to decide who gets access. The owner can assign, modify, or remove access permissions for other users. Discretionary access control (DAC) models allow the data owner to decide access control by assigning access rights.
How DAC works:
The resource owner manages access rights by editing the access control list
A file owner can grant read, write, or execute to users or groups by modifying the resource’s Access Control List (ACL)
Users with sufficient permissions may be able to re share access, depending on the system
Where DAC fits:
Small teams, ad hoc collaboration, short lived projects
Strengths:
Simple and flexible
Fast to set up and change
Limitations:
Owner errors and re sharing can create potential security gaps
Harder to audit as multiple users grant access informally
Good practice:
Set expiries on shares
Review DAC permissions every 90 days
Limit who can re share
Mandatory Access Control (MAC)
Mandatory access control places strict security standards , centrally defined policies on users and data. Users cannot change permissions themselves. Mandatory access control (MAC) places strict policies on individual users and the data they want to access.
How MAC works:
A central authority defines security labels for objects and clearances for users
Users can only access a resource if their clearance is equal to or higher than the resource’s label
System enforced rules apply consistently across the environment
Where MAC fits in the broader context of security systems :
Government, defence, and highly regulated environments handling sensitive data
Strengths:
Strong confidentiality and consistent enforcement
Prevents owner level permission changes
Limitations:
Rigid and change heavy
Requires a clear, well maintained label taxonomy
Good practice:
Keep label sets simple and documented
Use a formal downgrade workflow
Train staff to classify data correctly at creation
Role Based Access Control (RBAC)
Role based access control creates permissions based on groups of users, the roles users hold, and the actions users take. Users inherit access from their assigned roles.
How RBAC works:
Define roles such as Accounts Payable Clerk or Service Technician
Map permissions to roles, then map users to roles
Use role hierarchies and separation of duties to prevent conflicting access
Where RBAC fits:
Medium to large organisations with stable job functions
Strengths:
Scalable and auditable
Aligns with HR structures and simplifies onboarding and offboarding
Limitations:
Risk of role explosion if every exception creates a new role
Less dynamic than context based models
Good practice:
Start with a small, well named role catalogue and refine quarterly
Automate joiner, mover, leaver workflows
Enforce separation of duties rules
Attribute Based Access Control (ABAC)
Attribute based access control is a dynamic, context based policy model that defines access by evaluating user, resource and environmental attributes. It is well suited to modern IT environments with hybrid work, which helps to limit access for unauthorized users .
User attributes: department, job title, certifications, training status
Resource attributes: data sensitivity, project tag, data owner
Environment attributes: time of day, location, device posture, network risk
Attribute-based access control (ABAC) is a dynamic, context-based policy that defines access based on policies granted to users
A policy engine evaluates attributes and makes access control decisions to grant or deny
User attributes: department, job title, certifications, training status
Resource attributes: data sensitivity, project tag, data owner
Environment attributes: time of day, location, device posture, network risk
A policy engine evaluates attributes and makes access control decisions to grant or deny
Where ABAC fits:
Multi cloud, partner access, dynamic conditions that change frequently
Strengths:
Fine grained, adaptable, reduces the need for exception roles
Aligns with Zero Trust and continuous evaluation
Limitations:
Policies can become complex
Requires reliable, governed attribute sources
Good practice:
Keep policies modular and testable
Govern attribute quality and ownership
Test policies in report only mode before enforcement
Rule Based Access Control (RuBAC)
Rule based access control applies administrator defined rules to govern access to corporate resources. It complements RBAC and ABAC for deterministic conditions.
How RuBAC works:
Administrators create predefined rules such as time based, location based, or network based conditions
Access can be denied based on rules such as time based restrictions for entry
Rules are evaluated at request time and the system grants or blocks access accordingly
Strengths:
Easy to understand and quick to implement for narrow use cases
Limitations:
Rule sprawl and brittle logic if unmanaged
Less expressive than ABAC for rich context
Identity And History As Signals, Not Standalone Models
Identity Based Access Control is best treated as verifying the user’s identity as part of authentication, then using that identity in policy.
History Based Access Controls use past interactions and behaviour patterns as inputs to policy, for example flagging unusual resource access compared to typical activity. These signals strengthen ABAC and help mitigate potential data breaches, enabling risk adaptive decisions rather than replacing established models.
Physical Access Control Versus Logical Access Control
Physical access control governs who can enter or exit specific locations, while logical access control governs who can access systems, applications and data. The same principles apply across both.
Physical access systems:
Controllers and panels evaluate policies and fire door relays
Readers accept cards, fobs, mobile credentials, or biometrics
Door furniture and sensors report door state and support anti passback
Visitor Management Systems track guests and provide temporary access
Muster reporting shows who is on site during emergencies. Physical access control systems govern who can enter and exit specific physical locations.
Controllers and panels evaluate policies and fire door relays
Readers accept cards, fobs, mobile credentials, or biometrics
Door furniture and sensors report door state and support anti passback
Visitor Management Systems track guests and provide temporary access
Muster reporting shows who is on site during emergencies
Logical access systems:
Identity providers manage accounts and user permissions
Policy decision points evaluate requests, and enforcement points protect apps and data
Multi factor authentication strengthens login to restrict access to authorised users. Multi-factor authentication (MFA) requires two or more verification methods to prove a user’s identity.
Logs record user activity and access requests for review
Integration tips:
Align physical and logical identities where practical
Alert on impossible travel or badge login mismatches
Feed door and application logs into the same monitoring platform for continuous visibility
Modern Patterns That Extend Traditional Models
Modern access control solutions combine models under policy driven control and continuous monitoring.
Policy Based Access Control: centralises policies and distributes them consistently across systems
Risk Adaptive Access Control: evaluates device posture, user behaviour and session risk, stepping up authentication or limiting access when risk rises
Break Glass Access Control: creates a tightly controlled emergency account that bypasses regular permissions to restore services, with strict logging, short expiry and post incident review
Cloud Based Access Control: uses cloud platforms to manage policies and credentials across sites and applications
AI Driven Identity Management: evaluates permissions in real time, detects anomalies, and predicts risky access patterns so teams can intervene early
Access Management Processes And Access Control Methods
Effective access management combines technology with disciplined processes.
Principle Of Least Privilege: grant the minimum access necessary to perform job functions
Automate User Provisioning And Deprovisioning: reduce manual processes and remove access promptly when roles change
Regular Audits: enforce least privilege and identify overprivileged or inactive accounts
Integrate With Existing Applications: avoid workarounds by ensuring policies flow into current tools and systems
Prohibit Shared Accounts: enable accountability and accurate investigations
Employee Training: teach users why access controls matter and how to follow procedures
Zero Trust Architecture: continually verify users, devices, and sessions, and use micro segmentation to limit blast radius
Continuous Monitoring: watch for unusual access events and policy violations in near real time
Strong Passwords And MFA: require unique, long passwords and at least two factors for sensitive systems. Employing strong passwords and multi-factor authentication significantly enhances security in access control systems.
Policy Testing Before Enforcement: simulate policy changes and confirm outcomes before enabling them in production
Choosing An Access Control Model: Decision Matrix
Choose the model that fits your data sensitivity, scale, rate of change, and allows for varying access. Scores run 1 to 5 where 5 is a strong fit.
Criterion
DAC
MAC
RBAC
ABAC
RuBAC
Data Sensitivity
2
5
4
5
3
Scale To Many Users
3
3
5
4
3
Rate Of Change
4
2
3
5
3
Audit And Compliance
2
5
5
4
3
Admin Overhead
4
2
4
3
4
Policy Expressiveness
2
3
3
5
3
Fit For Hybrid Work
3
2
4
5
3
Use RBAC as the backbone in most organisations, add ABAC for dynamic, context based control, apply RuBAC for deterministic rules, use DAC for short term collaboration with expiries, and reserve MAC for the highest assurance environments.
Frequently Asked Questions
What Are The Main Types Of Access Control
The main models are Discretionary, Mandatory, Role Based, Attribute Based, and Rule Based Access Control. Most organisations blend models to balance control, simplicity and context.
How Does An Access Control System Work
The system identifies the user, authenticates the identity, evaluates policies and access rules, then grants or denies the request and records the access event.
What Is The Difference Between RBAC And ABAC
RBAC grants access based on job roles, while ABAC evaluates user, resource and environment attributes to make dynamic access decisions. RBAC is simpler to operate. ABAC is more expressive for modern environments.
What Is An Access Control List
An access control list is a table that states which users or groups have which permissions on a resource, such as read, write or execute.
Does History Or Identity Alone Decide Access
Identity proves who you are during authentication, and history informs policy as a risk signal. Both are inputs to policy rather than standalone access control models.
What Is Break Glass Access
Break glass is an emergency account that bypasses normal permissions to restore services. It must be time bound, heavily logged and reviewed after use.
Implementation Checklist For Your Team
Define data owners and facility owners for critical resources
Document access control policies with clear owners and expiry dates
Map roles and attributes before writing policies
Automate joiner, mover, leaver workflows
Require multi factor authentication on sensitive systems
Prohibit shared accounts and enforce strong passwords
Log access events and monitor continuously
Schedule quarterly privileged access reviews and semi annual standard reviews
Test policy changes in a safe environment before enforcing
Train employees on access procedures and visitor processes
Integrate access control with existing systems to avoid workarounds
Summary
Access control protects physical spaces and digital assets, including customer data, by ensuring only authorised users get the right level of access at the right time. DAC empowers owners, MAC enforces strict labels, RBAC scales with roles, ABAC adapts with context, and RuBAC codifies precise rules. Combine models, automate provisioning, audit regularly, and train people so policies hold up in the real world.
Castle Security designs and deploys access control solutions in Perth, WA. from physical access systems with mobile credentials and biometrics to modern access management for applications and data. We can assess your environment, align access control models with your policies, and integrate with your existing infrastructure.
Discuss cloud based access control, visitor management and multi factor authentication
Call Castle Security or request a callback to get secure access working the way it should.
Louis Thorp
When he’s not providing quotes to our clients or juggling the management of Castle Security, Louis is working with the Marketing Team on the website or out talking to clients. For over 12 years, Louis has been at the forefront of new business.
Louis Thorp
When he’s not providing quotes to our clients or juggling the management of Castle Security, Louis is working with the Marketing Team on the website or out talking to clients. For over 12 years, Louis has been at the forefront of new business.
