Mandatory vs. Discretionary Access Control (MAC vs. DAC): Access Control Fundamentals Comparison

Regulating user access to resources and information is a crucial aspect of IT security, especially since 77% of organizations experienced cyber attacks or data breaches in 2024 due to improper access controls or overly privileged users.

This finding highlights the need for a robust identity and access management (IAM) strategy, with mandatory access control (MAC) and discretionary access control (DAC) among the most common approaches. We’ll tackle these types of access control in this post, exploring their strengths, limitations, and applications.

What Is Mandatory Access Control (MAC)?

MAC is a powerful security model that enforces strict access control through a centralized system, with access decisions explicitly limited to software developers or system administrators.

Access decisions depend on clearance levels assigned to users and security labels attached to resources. The security labels depend on the sensitivity of the data. For example, an organization may categorize data as unclassified, sensitive, secret, and top secret.

Meanwhile, the clearance level denotes the highest level of classified information a user is authorized to access, typically corresponding to the security labels (e.g., unclassified clearance, sensitive clearance, top secret clearance, etc.).

When a user attempts to access information, the MAC system compares the user’s clearance level to the resource’s security label before making an access decision—to grant or deny access to the user.

When to Use MAC

MAC is commonly implemented in high-stakes environments where data confidentiality and integrity are critical, such as matters of national security, public safety, or severe financial consequence. Below are some of the sectors where MAC is used.

• Government and military: This is where the most classic application of MAC is employed since this sector deals with classified and highly sensitive information, which helps keep national secrets and critical intelligence safe.

• Finance: Banks rely heavily on MAC to protect sensitive customer and financial records. MAC helps prevent fraud and increase customer trust since it ensures that only authorized users with the right clearance can access and modify records.

• Healthcare: MAC is a must-have for controlling access to electronic health records (EHRs), as it helps maintain patient information privacy. MAC also assists healthcare organizations in adhering to regulations, such as the Health Insurance Portability and Accountability Act (HIPAA).

What Are the Benefits of Using MAC?

The primary advantage of using MAC is that it offers strong security, as it uses strict, predefined rules to protect sensitive data. Since access is managed centrally, MAC only lets authorized users in, reducing the risk of accidental permission sharing.

This robust security is also consistent, as MAC applies the same rules everywhere, reducing human error—a significant cause of security breaches—and maintaining a standardized security setup.

For organizations with strict regulatory requirements, MAC simplifies compliance. It ensures access controls perfectly match legal and regulatory requirements, helping you avoid fines and legal penalties.

What Are the Limitations of Using MAC?

While MAC offers strong access security, it has some drawbacks, topped by inflexibility. It is slow to adapt to changing business needs, as every access adjustment requires intervention from system administrators. 

Setting up a MAC system is also complicated, as it requires extensive planning and administrators must have a deep understanding of the organization’s security needs. As such, it demands bigger monetary investments—from initial setup to monitoring, regular policy updating, and personnel training.

MAC may also affect user experience since users can’t change permissions on their own, which can make things slower and more frustrating, especially for teams that need to share information often.

What Is Discretionary Access Control (DAC)?

DAC is an access control system that allows data owners to determine who can access their information and what kind of actions they can perform (e.g., read, write, or execute). 

So, if you create a document on your computer, you can choose to make it readable by everyone, editable by specific people only, or completely private.

DAC operates on two core concepts—subjects and objects. Subjects refer to users or user groups attempting to access resources protected by DAC, while objects refer to the system resources, such as files, databases, or applications.

When a subject attempts to access an object, they first need to identify themselves through authentication. Subsequently, the system verifies if they possess the necessary rights to access that specific object.

DAC systems determine who can access a resource by using access control lists (ACLs) attached to each object. The lists contain information about authorized users and their corresponding privileges.

When to Use DAC

DAC is well-suited for environments where collaboration is essential, such as for teams that require frequent information sharing. The flexibility it allows simplifies the process of granting and adjusting permissions on the fly, making it ideal for startups and other types of organizations that prioritize speed and simplicity.

Consumer-facing applications also use DAC, including social media platforms (you decide who can see and comment on your posts) and cloud storage systems (you can choose who to share with and their access type—view only or edit).

Another application of DAC is in smartphone apps. Every time an app asks for permission to access your camera, contacts, location, or photos, that’s DAC in action. You, as the phone and data owner, decide whether to grant or deny access.

What Are the Benefits of Using DAC?

DAC offers several benefits, especially in environments where flexibility and user autonomy are valued. The biggest advantage is that resource owners can decide who gets access and what they can do with the data.

DAC systems are generally simpler to understand and manage than more rigid models. Users can often grant or revoke access directly without going through a central administrator for every change, which can save time and reduce administrative overhead.

DAC also facilitates collaboration. In environments where people frequently share information and work together on projects, DAC makes it easy to grant temporary or specific access to collaborators, boosting productivity.

Since individual owners manage access to resources, IT administrators don’t have to handle every single access request for every piece of data, freeing up time for more critical security tasks.

What Are the Limitations of Using DAC?

Despite its many benefits, DAC also comes with some limitations. For one, it is more prone to human error and is, therefore, less secure. Since individual users set permissions, there’s a higher chance of accidental mistakes or misconfigurations that can expose sensitive data. Users may grant too much access or not realize the implications of their choices.

Its decentralized nature may also make it difficult for administrators to get a clear picture of who has access to what information across the entire system. This makes it harder to enforce consistent security policies.

Using DAC systems may also increase the risk of privilege creep, a dangerous situation where users accumulate unnecessary access rights. This further expands the organization’s attack surface.

MAC vs. DAC : Side-by-Side Comparison

The table below provides more details on the differences between MAC vs. DAC.

MAC vs. DAC : Which Access Control to Choose?

Choosing between MAC and DAC is not simple since there is no universal best access control solution. The choice depends on several factors, such as an organization’s specific needs, risk tolerance, and industry. Here are a few guidelines that can help organizations make the right decisions.

• Assess data sensitivity and regulatory requirements. If your organization handles highly sensitive data or operates within a highly regulated industry, MAC is likely the superior choice. Its strict requirements and compliance-friendly nature make it the more secure option. In contrast, if your data is less sensitive and your primary goal is to foster collaboration and agility, DAC can be a more appropriate fit.

• Consider the size of your organization and agility needs. For extensive access control across complex structures, or in environments where strong security enforcement is critical, MAC offers the necessary control and consistency. However, smaller or early-stage teams and internal systems that prioritize collaboration and quick adjustments may find DAC more suitable. Startups and small businesses, for instance, often prefer DAC due to its user-friendliness and lighter administrative load.

• Evaluate administrative capacity and expertise. An organization must assess if it has the necessary resources and knowledge to meticulously plan and execute the implementation of a MAC system. DAC, on the other hand, shifts the administrative burden to individual owners.

That said, organizations don’t have to choose just one access control strategy. The most effective approach would be to combine the two.

Conclusion: Using Both MAC and DAC

Organizations can leverage the unique strengths of MAC and DAC for different security needs. For example, they can deploy MAC for core security, especially for critical parts of the network where security cannot be compromised. This includes things like direct database access, how different internal services talk to each other, and other crucial backend operations that demand strict control.

DAC is best for guaranteeing the best user experience. Organizations can apply it to the frontend, where users interact directly and set their own content sharing preferences. Giving users control over their own data in these areas makes the application more flexible and intuitive, while the backend remains tightly secured by MAC.