What is the Principle of Least Privilege (PoLP)?

The Principle of Least Privilege (PoLP) maintains that a user should only have access to resources, applications, and services necessary for their job. It grants the minimum level of access required to do one’s job. This reduces the attack surface for bad actors and limits malware spread.

You can also apply PoLP to your network devices. For example, a printer on the marketing floor shouldn't be able to access the HR database. Additionally, your network admins might have elevated privileges, but even they follow strict protocols. They only use their elevated accounts when necessary, otherwise, they operate under regular user accounts.

Benefits of implementing PoLP in company networks

Enhances overall security

Limiting access rights to the bare minimum required for tasks reduces the chances of accidental or intentional misuse. For instance, if a marketing employee doesn't have access to financial data, they can't accidentally delete or alter it.

Minimizes damage during security breaches

Say an attacker gains control over a user’s account. If PoLP is in place, the attacker will only have access to the limited resources that the user was authorized to use. This containment can prevent widespread damage and gives you crucial time to react and mitigate the issue.

Improves compliance with regulations

Many standards, like GDPR and HIPAA, require strict control over who has access to what information. By adhering to PoLP, you naturally align yourselves with these requirements. For example, restricting access to personal customer data to only those who need it helps you stay compliant with GDPR guidelines.

Boosts productivity

PoLP helps boost their productivity by reducing the noise and distractions employees face. When access is restricted, employees don't get overwhelmed by unnecessary information. This streamlined access helps them focus better on their tasks.

Simplifies audits and monitoring

When access privileges are tightly controlled, it's easier to track who did what and when. This level of visibility is invaluable during an audit. If an issue arises, you can quickly trace the problem back to its source. For example, knowing exactly which user accessed sensitive files at a particular time can be critical for investigations.

Incorporating PoLP not only strengthens your security posture but also brings operational efficiencies, helping you create a safer and more productive work environment.

How to identify and classify resources for PoLP

The principle of least privilege dictates that users should only have the minimum levels of access – or permissions – necessary to perform their job functions. Determining the level of access to grant each role demands identifying and classifying resources accordingly, which is accomplished in several steps.

Identifying resources

Resources can be anything within your system that requires limited access control. This includes your databases, files, documents, software, servers, networks, hardware devices, user accounts, service accounts, and APIs.

Classifying resources

Once you have identified your resources, you classify them based on various criteria, starting with their sensitivity. Your data can be classified as confidential, meaning it could cause harm if accessed without authorization.

Data can also be classified as internal, which means it’s intended for internal use but is not highly sensitive. It can also be classified as public. This is data that can be accessed by the general public without causing harm.

You can also classify data based on its importance. For instance, critical data is essential for the operation of the organization. Downtime or unauthorized access could have severe implications. Non-critical data is important but not essential for immediate operations.

Lastly, you can classify data based on its usage:

• Read-only: data that can be viewed but can’t be modified.
• Read-write: data that can be both viewed and modified.
• Execute: applications or scripts that can be run.

Assigning roles and permissions

After classifying your data and resources, you should then create roles based on job functions and assign the least privileges necessary for those roles to access the necessary resources. Consider the following:

• Role-based Access Control (RBAC): Define roles and assign permissions to these roles rather than to individual users.
• Attribute-based Access Control (ABAC): Define access based on attributes (e.g., user role, department, location).
• Time-based Access Control: Allow access only during specific times if applicable.

We will cover these in greater detail below.

Implementing controls

Now that you have assigned roles, use the identified roles and permissions to set up access controls. You can use Access Control Lists (ACLs) to specify which users or roles can access which resources.

You must regularly review user access to ensure compliance with PoLP. You can use Identity and Access Management (IAM) systems and other tools that automatically enforce PoLP to ensure users are complying with their assigned access privileges.

You should also continuously monitor access to resources to detect and respond to unauthorized access attempts. Conduct regular audits of access logs and permissions to ensure adherence to PoLP.

Regularly reassess resources, roles, and permissions to adapt to organizational changes and emerging security threats. Update policies and procedures as necessary to maintain effective PoLP.

Types of access control used to enforce PoLP

Role-based access control (RBAC)

Role-based access control (RBAC) restricts network access based on an individual's role within the company. It uses roles to separate levels of access employees have to the network. Each role dictates what data and applications an employee can access.

When you use RBAC, employees can only access the information they need to do their jobs. Access might depend on factors like authority, responsibility, and job competency. So, a project manager might have access to project files but not HR records.

With RBAC, you can limit what actions employees can perform, such as viewing, creating, or modifying files. This limitation helps keep sensitive data secure. For instance, an engineer might modify project documents but can't access payroll information.

You can control what users can do at both broad and granular levels. For example, let's say you have three types of roles: administrators, specialists, and end-users. Administrators might manage network settings, specialists might have access to specific datasets, and end-users might only have read-only access to certain files.

If an employee changes jobs within the company, you might need to adjust their role. This adjustment can be done manually or more efficiently by assigning roles to groups. For instance, if someone switches from sales to marketing, their role can be reassigned to the marketing group, granting them the necessary permissions.

Some specific designations in an RBAC system include management role scope, management role group, and management role assignment. For example, a management role scope could limit IT staff to managing only network settings. A management role group might include all IT staff, and a management role assignment links these roles together, ensuring the right people have the right access.

Adding a user to a role group gives them access to all roles in that group. If they leave the group, their access is revoked. For instance, if a contractor needs temporary access to specific files, they can be added to a role group and removed once their work is done.

Attribute-based access control (ABAC)

ABAC is a dynamic and flexible approach to access control that bases permissions on attributes, rather than fixed roles or identities. Unlike Role-Based Access Control, which assigns permissions based on predefined roles, ABAC allows for more granular and context-aware control by considering various attributes related to the user, the resource, and the environment.

Attributes can be specific to users, meaning characteristics of the user attempting to access a resource, such as their role, department, security clearance, and job function. They may also describe properties of the resource being accessed, such as sensitivity level, resource type, and owner.

Attributes may also refer to contextual factors at the time of access, such as time of day, location, and device being used. Or they may be the specific action the user is attempting to perform, such as read, write, delete, or execute.

ABAC also sets policies, which are rules that define which combinations of attributes allow or deny access. These policies are usually expressed in a policy language and can be highly specific and complex.

ABAC allows for fine-grained access control, considering multiple attributes and context, leading to more precise access decisions. It’s also noted for its flexibility. Policies can be easily modified to adapt to new requirements without changing user roles or permissions.

Network administrators also rate ABAC highly on scalability. It can handle complex environments with a large number of users and resources more effectively than RBAC. It is also context-aware, with the ability to incorporate dynamic attributes such as time and location.

Just-in-time (JIT) access

With Just-in-time (JIT) access, users get access to resources only when they need it. And once that need is gone, the access is revoked. This minimizes the risk of unnecessary or unauthorized access.

Imagine a developer needing to update a piece of software. With JIT, they get the necessary permissions just for the duration of their task. After that, their elevated access is automatically removed.

You can use tools like Azure AD Privileged Identity Management to manage JIT access. It provides time-bound access, ensuring that elevated permissions are temporary. 

For example, a project manager might need access to sensitive financial data for a quarterly review. They request access, stating their reasons, and once approved, they can access the data for a set period. After the review, their access is removed without them having to do a thing.

Another example is during an incident response. Security analysts might need admin-level permissions to investigate and mitigate a threat. With JIT, they get the access they need quickly, handle the situation, and then their elevated permissions are automatically revoked.

This approach not only tightens security but also keeps your audit trails clean. You know exactly who had access to what and when. It's efficient and keeps your network robust against potential breaches.