What is the principle of least privilege?

The principle of least privilege, sometimes referred to as PoLP, is a cybersecurity strategy and practice that is used to control access to organizations’ data, networks, applications, and other resources by closely monitoring and controlling access privileges granted to users. Extending beyond human users, the principle of least privilege also applies to non-human users, such as applications, systems, and connected devices that require privileges or permissions to perform a required task. Users are provided the minimum level of access necessary to perform the tasks necessary to do their jobs, and nothing more. 

See how a zero trust security model helps enforce the rule of least privilege with automated role management and permissions and access policy logic.

Examples of the principle of least privilege in practice include:

  • An employee whose job entails processing invoices would only have access to that specific function in an accounting application rather than access to other areas, such as accounts receivable or payroll processing. 
  • A salesperson would have read and write privileges for a customer database, but not download or copy privileges. 
  • Government workers would only have access to information based on their security clearance levels and only be able to access information relevant to their job (e.g., an FDA (Food and Drug Administration) employee could not access defense-related information). 
  • A software user interface designer would not have access to source code. 

The principle of least privilege is widely considered one of the most effective cybersecurity practices, because of its efficacy in restricting lateral movement and unauthorized access, minimizing attack surfaces, and reducing the spread of malware. It is an effective strategy for meeting the goals of the CIA triad (confidentiality, integrity, and availability) as well as a foundational part of zero trust security frameworks.

How the principle of least privilege works

The principle of least privilege works by restricting and monitoring access to data, networks, applications, and other resources. In a zero trust security environment, the principle of least privilege can help identify the specific access granted to these human and non-human users, regardless of the IP (internet protocol) address, protocol, or port an application uses (e.g., communication and collaboration applications that use dynamic ports).   

Core elements of the principle of least privilege

The principle of least privilege incorporates three core elements in its controls—user identity authentication, device security posture, and user-to-application segmentation. 

User identity authentication 
The first step to enforcing the principle of least privilege is to validate the identity of human and non-human users.

Device security posture 
Effective use of the principle of least privilege involves monitoring usage to identify and stop a compromised human or non-human user.

User-to-application segmentation 
The principle of least privilege uses a zero trust network access solution to prevent unauthorized lateral movement by segmenting networks and restricting access based on need. 

Principle of least privilege account types 

To implement the principle of least privilege, different account types are used, each with varying levels of privileges related to user requirements. The types of accounts that are used include the following. 

Non-privileged accounts 
There are two main types of non-privileged accounts: 

  1. Least-privileged user accounts (LPUs) give users as little access as possible to allow them to perform their duties. This level of account is assigned to most users. 
  2. Guest user accounts are assigned to external users (e.g., third party partners, contractors, contingent workers, etc.) who require minimal access. Guest user accounts, generally, have fewer privileges than LPUs. Following the principle of least privilege, guest user accounts should be turned off as soon as access is no longer required.     

Privileged accounts 
Also referred to as superuser or admin accounts, privileged accounts have the highest level of access.

See how to extend your identity investment to privileged accounts.

Privileged accounts that are commonly used include:   

  • Application accounts are used by applications to provide access to other applications, access databases, or run batch jobs or scripts.  
  • Domain administrative accounts have administrative access across workstations and servers within the domain. 
  • Domain service or Active Directory accounts have the authority to enable password changes to accounts and manage and store information about resources. 
  • Emergency accounts, also called break glass or firecall accounts, are used by non-privileged users with administrative access to secure systems in the case of an emergency. 
  • Local administrative accounts provide administrative access to the local host or instance only. 
  • Service accounts, also called privileged local or domain accounts, are used by an application or service to interact with the operating system. 

With the principle of least privilege, usually only administrators have access to privileged accounts. This is because they are considered to be the most trusted and require elevated access privileges to perform their duties. Among the tasks that a privileged account holder can perform are: 

  • Activating or deactivating other user accounts, including privileged accounts 
  • Adjusting network settings 
  • Installing and updating applications 
  • Monitoring users and systems 
  • Removing data 

Service accounts 
Service accounts are assigned to non-human users that require a dedicated account. According to the principle of least privilege, access requirements should be determined; then, access is limited to the bare minimum needed to execute authorized tasks.  

Shared accounts 
Also called generic accounts, shared accounts are shared among a group of users. Shared accounts should be used judiciously, as it is a principle of least privilege best practice for each individual user to be assigned their own account. 

Three principle of least privilege implementation best practices

  1. Create and maintain an inventory of all privileged accounts, including user and local accounts, application and service accounts, database accounts, cloud and social media accounts, SSH (secure shell) keys, default and hard-coded passwords, and other privileged credentials (e.g., those used by partners or vendors). The inventory should also include platforms, directories, and hardware.
  2. Enforce the principle of least privilege over end users, endpoints, accounts, applications, services, systems, and devices. This can be done by: 
    • Banning password sharing 
    • Eliminating unnecessary privileges from applications, processes, devices, tools, and other resources 
    • Implementing segregation of duties policies 
    • Minimizing the rights granted to each privileged account based on need
    • Minimizing the rights granted to each privileged account based on need
    • Removing hard-coded credentials  
    • Removing admin rights on endpoints and servers 
    • Requiring the use of strong passwords and multi-factor authentication 
    • Restricting the assignment of privileged accounts
    • Segmenting systems and networks as much as possible 
    • Using standing privileges only when necessary
  3. Establish a comprehensive principle of least privilege rules to govern how accounts, especially privileged accounts, are provisioned and deprovisioned as well as how privileged identities and accounts are monitored and managed. 

Why the principle of least privilege is important 

The principle of least privilege is important because it addresses security challenges related to growing hybrid environments in a way that balances usability and security while enhancing performance and reducing the impact of human error.  

Using the principle of least privilege as a foundational element in security strategies helps protect organizations from the fallout from unauthorized access to resources and data.

This includes financial and reputational losses from data breaches, ransomware attacks, and other malicious activities. 

Another reason why the principle of least privilege is important is that it reduces the enterprise’s attack surfaces. Not only does this minimize risk and vulnerability, but it also saves valuable IT and security teams’ time and money. In addition, it cuts down the threats that need to be addressed to defend against attackers who seek to gain access to critical systems and sensitive data by compromising a low-level account.  

Applying the principle of least privilege can also stop the spread of malware by enforcing least privilege on endpoints. This stops malware attacks from using elevated privileges to increase access and move laterally, infecting other systems. 

The principle of least privilege also keeps unauthorized inside users from accessing sensitive information and systems. This increases overall data security, addresses regulatory compliance requirements, and decreases instances of malicious insider activity.    

Benefits of the principle of least privilege

Audit readiness
The monitoring, logging, and reporting capabilities that come with implementing the principle of least privilege provide much of the information needed for audits. This streamlines the audit process and ensures compliance with regulations’ security requirements.

Better data classification 
The principle of least privilege requires network managers to keep an inventory of who has access to what at any given time, which helps keep networks secure and healthy.   

Enhanced visibility 
Implementing the principle of least privilege requires increased visibility for users’ activities. This helps expedite the identification and mitigation of cyberattacks and malicious insider activities.   

Improved data security 
Using the principle of least privilege in security strategies can prevent the catastrophic effects of data breaches by limiting the amount of information that a person can access to only what they need to do their jobs. Since most users only require minimal data, the risk of damage from a breach is significantly reduced. 

Increased protection for IT assets 
Principle of least privilege security benefits extend beyond protections from cybercriminals. PoLP protects data, systems, networks, and other resources from the negative impact of human error on data, systems, and networks, resulting from mistakes, malice, or negligence, by limiting users’ access to only resources that they need to complete their tasks. 

Minimized attack surface 
The principle of least privilege minimizes the attack surface. It reduces the paths that cybercriminals can use to access sensitive data or carry out an attack by confining them to the minimal resources that the user is authorized to access.   

Operational efficiency and performance 
The PoLP enhances operational efficiency and performance with reductions in system downtime that might otherwise occur as a result of a breach, malware spread, or unsanctioned applications. 

Stunted malware propagation 
The principle of least privilege limits the spread of malware across networks by preventing the lateral movement that can be used to launch an attack against other connected devices. It also prevents users from installing unauthorized applications and enforcing privilege separation. 

Implementing the principle of least privilege

Following are several steps that an organization can take to implement the principles of least privilege. 

Conduct an audit of privileged accounts  
Regular reviews of privileged user accounts are an important function of the principle of least privilege, including checking identities and rights to the network, systems, software applications, processes, and programs.  

Disable unnecessary resource access 
A security program following the principle of least privilege will deactivate default privileges and reinstate those that are needed based on actual requirements.   

Elevate privileges on a case-by-case basis 
To maintain the efficacy of an implementation of the principle of least privilege, users should be granted elevated privileges on a situational basis, and the access should be temporary.   

Eliminate unused accounts 
The principle of least privilege also includes no privilege. If a user no longer has a requirement for access to all or part of a set of resources, their privileges should be revoked immediately. Systems should be in place to regularly assess usage to ensure optimal access control.   

Monitor endpoints 
Implement the principle of least privilege by continuously monitoring, logging, and auditing all activity on endpoints as well as maintaining an endpoint inventory.  

Review logs regularly 
The principle of least privilege includes monitoring and logging usage. An ongoing scheduled review of logs is critical. Without reviewing logs, unauthorized access could go undetected.   

Reevaluate accounts and privileges 
To optimize the efficacy of a principle of least privilege implementation, access rights should be reviewed on a monthly basis or quarterly at a minimum. If excessive privileges are identified, they should be revoked immediately. Any dormant accounts should also be evaluated to determine if they should remain active.   

Separate users  
Separating users into groups with higher and lower access levels and subgroups based on their roles or locations is also necessary when implementing the principle of least privilege.   

Set user access to minimal privileges 
When implementing the principles of least privilege, minimal privilege should be used as the default setting. If a user needs additional privileges to perform a task that requires additional access, it should be revoked when it is no longer needed to prevent privilege creep. 

Use privilege bracketing 
Privilege bracketing enforces the principle of least privilege by granting only the amount of time a user needs to complete their task. 

Terms and Concepts Related to the Principle of Least Privilege

Privilege creep  
Privilege creep happens when users are granted additional access rights over a period of time. Often, privilege creep occurs when a person is given new access rights when they change positions or take on new responsibilities, but existing privileges that are no longer needed are not revoked. The result is an accumulation of access rights or privilege escalation that go beyond what is actually required.

Applying the principle of least privilege deters privilege creep by regularly reviewing and updating access permissions.

Privilege bracketing 
Privilege bracketing is the practice of increasing access permissions just before it is required, then revoking it as soon as the related task has been completed. This allows privilege levels to be elevated for the shortest period of time.  

Privilege separation 
With privilege separation, the functionality of a system is divided into separate parts. Users are assigned access to specific parts based on requirements, thereby limiting exposure and reducing the attack surface.  

Privilege escalation 
Privilege escalation is a type of cyberattack where an attacker gains unauthorized access to elevated rights or privileges. By applying the principle of least privilege at endpoints, privilege escalation attacks are stunted, because the attacker is not able to use elevated privileges to increase access and move laterally to execute malware or other nefarious activities. 

Zero trust security 
Zero trust security is based on the concept that no device, user, workload, or system should be trusted by default, regardless of whether it is inside or outside the security perimeter. Other security models have implicitly assumed that anything inside of the network should be trusted, because it has been validated as authorized and legitimate. In a zero trust model, every access request is evaluated and authorized before access is granted. 

Zero trust network access (ZTNA) 
Also known as software-defined perimeter (SDP), ZTNA controls access by microsegments where valuable assets reside. ZTNA then applies the principle of least privilege to identify and stop malicious or unauthorized lateral movement.  

The principle of least privilege provides maximum benefits

Effectively implemented and enforced, the principle of least privilege does yeoman’s duty for security. It helps improve cybersecurity and security controls related to human error while improving productivity and performance.  

The list of benefits delivered by applying the principle of least privilege is lengthy and proven. Organizations of all sizes and in all segments are encouraged to adopt the principle of least privilege as a pillar in their security postures. 

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