Don’t give employees, devices, and third parties more access privileges than they need. This is the basic concept behind the principle of least privilege (PoLP). As cyber-attacks and insider threats loom large, controlling access to IT resources and data is essential. Using the least privilege approach to data security helps prevent data breaches and other cyber-attacks. Security experts have counted 35,900,145,035 data records breached globally between January and May 2024. We know that many of those breaches exploited (often excessive) access privileges, so enforcing least privilege access is a fundamental security posture.

A brief history of the principle of least privilege (PoLP)

Almost 50 years ago, Jerry Saltzer and Michael Schroeder of MIT developed an IT system design concept and security principle named “the notion of least privilege.” This idea has become a fundamental framework for robust security strategy. The paper outlining least privilege states:

“Every program and every user of the system should operate using the least set of privileges necessary to complete the job.”

Decades later, this concept is reiterated by the National Institute of Standards and Technology (NIST):

"NIST seeks to ensure the right people and things have the right access to the right resources at the right time."

Today, enforcing least privilege access rights across an organization's broad user base, including third-party vendors, facilitates productivity and improves its security posture. Least privilege access control should be viewed as a cybersecurity best practice.

Effective enforcement of the least privilege principle requires governance controls to prevent unauthorized access. By controlling access, a company reduces the risk of accidental or malicious access events that cause data exposure, malware infection, and business-related scams like business email compromise (BEC).

Example of a cyber-attack that a least privilege approach could have prevented

Microsoft and Midnight Blizzard — January 2024

In January 2024, Microsoft became a victim of the Russian hacking gang Midnight Blizzard. The gang targeted Microsoft's cloud-based identity management platform, Entra ID. The attack involved various tactics, including leveraging access privilege settings in Entra ID. Initial access was gained by compromising a legacy, non-production test tenant account. The account used password access, with no MFA (multi factor authentication) enabled. The attackers guessed the weak password to gain initial access, which then enabled them to move laterally into Microsoft’s production account. Such lateral movement typically utilizes legitimate tools — like stolen credentials — and vulnerability exploits to move throughout a network, increasing privileges as it goes to gain ever-deeper access. Eventually, the attackers gained privileges within Microsoft’s Exchange Online tenant to acquire unrestricted access to corporate mailboxes — ultimately enabling them to access even more sensitive areas of the network.

Why is the enforcement of PoLP critical for security?

Enforcing least privilege would have helped mitigate the risk in the Midnight Blizzard cyber-attack. If admin accounts had been hardened using the right level of permissions, attackers would have had to work much harder to gain access. And subsequent privilege escalations would have easily been prevented using an identity governance and administration (IGA) service — which detects and prevents unexpected privilege changes.

In addition to mitigating unauthorized access-related cyber-attacks, enforcing the principle of least privilege also prevents accidental insider threats. While overprovisioning user privileges can lead to data exposure, least privilege access ring-fences an organization’s data — reducing the risk of accidental data leaks and inappropriate data-sharing.

How can you implement least privilege access?

Getting ahead of privilege creep, i.e., an accumulation of privileges that do not reflect a user’s needs, requires you to implement the principle of least privilege across your IT resources. The following strategies will help you establish the least privilege approach to reduce security risk across your organization.

Implement an IGA solution

You need to have visibility and control of apps and access across your environment. This includes the ability to register and control shadow IT and SaaS apps. A modern IGA solution provides the functionality to identify, control, and apply least privilege access to your IT resources, people, and devices.

Perform regular access reviews

Access (or privilege) reviews identify user access privileges across your IT environment. By using an identity governance and administration (IGA) platform, like AccessOwl, a company can perform automated access reviews. These reviews are available as a workflow, and reminders are sent directly via Slack. Once a review is complete, all access changes are processed and documented. The results are then used to modify access based on the principle of least privilege, to ensure that minimum privilege is enforced.

Apply role-based access control (RBAC)

Least privilege access rights should be based on role needs. RBAC is a concept used to apply network and IT resource access that reflects the needs of an employee role. Roles are assigned specific access permissions, so all employees who perform the same role within an organization are granted the same access rights to network resources.

Deploy zero standing privileges (ZSP)

Another strategy that can be helpful in establishing least privilege permissions is to work from a default permissions basis, then adding on rights, as needed. This is a concept known as “zero standing privileges (ZSP)”. ZSP removes permanent privileges for employees within an organization, working on a just-in-time (JIT) access model. JIT access grants privileges for a limited time, as needed. ZSP reduces the security risks of administrative rights that are often targeted for privilege abuse. A modern IGA solution automates the deployment of a ZSP and RBAC model.

Monitor, analyze, and review privileges

Whatever strategy you use to implement and enforce the principle of least privilege, continuously monitoring user permissions is a good idea. People enter, leave, and change positions in a company. Privileged user accounts must be monitored, analyzed, and reviewed to ensure consistency in the application of least privilege. Some advanced IGA systems integrate with SaaS apps and use platforms like Slack to monitor, analyze, and review privileges — making it easier to perform these tasks. IGA automation is also used to quickly remove unused accounts, such as those of employees or others who have left the organization.

Challenges in implementing PoLP

When it comes to implementing a least privilege model, there are several fundamental challenges:

Determining the appropriate level of access for each role

Using an IGA tool to audit the entire IT environment will identify the current state of privileged accounts. These accounts can be held by employees, third-party vendors, devices, and other types of non-employees. This audit forms the basis for privilege analysis, building a map of privilege requirements upon which  least privileges are based. The audit will identify any exceptions to the baseline privileges needed per role to perform tasks.

Ensuring consistency across the entire IT environment, including remote workers

One of the biggest challenges is to ensure that privileges are enforced consistently across the entire IT environment — including those with remote access. Automation tools, like an IGA solution, can help ensure that remote access is granted on a need-to-know basis, using a just-in-time (JIT) access model, to mitigate opportunities for external attacks..

Challenges in changing privileges when people move between roles or leave an organization

Automating deprovisioning is essential to remove the risk of accidentally leaving an account active when an employee or contractor leaves an organization. Similarly, having a method to auto-modify privileges when roles in an organization change prevents employee access overreach — ensuring they have only the level of access they need to perform a task.

Shadow IT and the principle of least privilege

Shadow IT, i.e., unsanctioned app use, can challenge least privilege enforcement. If you’re unaware of the apps used by employees, it’s impossible to ensure that the correct level of privileges are applied to creating and sharing data. Modern IGA solutions, like AccessOwl, provide mechanisms to register apps and privileges, to ensure that any unsanctioned apps come under the control of a centralized registry. Adding a centralized identity governance layer to your identity and access management ensures that you can track app usage and ensure that least privilege is enforced.

Using IGA to streamline the principle of least privilege in a growing organization

As organizations grow, privileges must reflect new, merged, and exiting roles. Using manual methods to modify privileges is time-intensive and prone to error. Identity governance automation streamlines company-wide deployment of least privilege. Tasks such as access requests and approval workflows can be simplified using an IGA tool integrated into Slack. Provisioning and deprovisioning, which can take time and result in overprovisioning, are similarly automated using a modern IGA solution.

Compliance standards that require least privilege access

Many data security and privacy standards and regulations have specific requirements for controlling access to sensitive data. These requirements are typically linked to the principle of least privilege. Some of the regulations and standards that use PoLP as a framework for access control include SOC 2, ISO 27001, NIST CSF, HIPAA, HITRUST, PCI-DSS, and SOX controls.