Principle of Least Privilege

Should an employee whose job entails processing payroll checks have administrative access to the customer database? No! The least privilege principle applies in this situation.
A complicated, diverse discipline with numerous underlying tenets is information security. Any information security program should aim to achieve the CIA triad’s top three objectives: confidentiality, integrity, and availability. The principle of least privilege is a guiding principle that aids organizations in achieving these objectives.

The principle of least privilege, which deals with access control, states that a person should only have the minimal access privileges required to carry out a particular task or job and nothing more. As a result, a worker whose duties include processing payroll checks would only have access to that feature of a payroll application and not have administrative access to the customer database. Similar to how entry-level government employees shouldn’t have access to top-secret papers and financial specialists shouldn’t have access to application source code, marketing specialists should not require access to employee wage information to perform their duties.

The majority of us are aware of the idea of limiting access and regularly observe or put this idea into practice. A parking attendant with a valet key can park your car but cannot go into the closed glove box, console, or trunk. Parents utilize parental control on their home gadgets to limit children’s access to hazardous information. Ticketed airline passengers can board a plane but are not permitted in the cockpit.

In an information security system framework known as AAA — authentication, authorization, and accounting (or accountability) — least privilege falls under the second A. This framework takes care of the requirements to authenticate people requesting access to a network or other resource, establish what they are permitted to do (authorization), and keep track of all the actions they do (accounting or accountability).

What Is Not the Least Privilege

Least privilege is sometimes confused with but is different from, two similar security principles: need to know and separation of duties.

Need to know, which is frequently combined with least privilege, offers more specialized access control based on need. For instance, sales managers shouldn’t have ongoing access to the personnel files of their direct subordinates, only enough time to conduct each employee’s yearly performance assessment.

Separation of duties entails dividing up important work between two or more persons so that no one person has complete authority over any decision that can jeopardize the company. This rule could be applied, for instance, to stop an accounts specialist from creating fictitious vendor accounts and using those accounts to pay fictitious invoices in order to steal money from the business. Separation of duties is frequently utilized in addition to least privilege, just like the need to know.

Who and What Does Least Privilege Apply To?

In actuality, networks, devices, programs, processes, and services are all subject to the least privilege concept. All of them are considered objects (passive entities that contain or receive information) when it comes to access control. Examples of objects include systems, files, programs, directories, databases, ports, and more. Organizations must realize that the rule must apply to each of these entities because if any are compromised, the business or its data may be at risk.

What are some instances when the least privilege is used with entities that are not users? One is “hardening” a server by blocking pointless ports and deleting superfluous parts. Another is allowing a web application to just retrieve data — not modify or remove it. Another is to grant API access to just the information that it needs rather than the entire database’s contents.

The Importance of Applying the Least Privilege Principle

Although one of the most sensible security principles is the least privilege, companies frequently do not take the execution of this policy seriously enough. As we saw before, the CIA Triad’s objectives of maintaining confidentiality, integrity, and availability can be violated by the careless use of the least privilege. In the aforementioned instances:

• The availability is violated when a payroll processing clerk removes the client database.
• The confidentiality of employee compensation information is violated by a marketing professional.
• Integrity is violated by a financial professional who modifies application source code.
• A junior government employee violates confidentiality and integrity when they change top-secret records.

It’s also important to note that the OWASP Top Ten, which identifies frequent web app security flaws, specifically names inadequate or flawed access control or authentication as the root cause of at least four of the top ten web application security threats.

The fact that least privilege practices lower an organization’s attack surface is one of its most evident advantages. Organizations struggle to protect against an expansive assault surface. If, for instance, attackers come across insecure cloud-based databases, APIs without authentication restrictions, backdoors left in essential software, or servers that are completely accessible to all traffic, the results might be terrible. Any of these circumstances could result in damaging assaults or substantial data breaches, such as the recent incidents below, which partly happened because of an excessive or nonexistent level of privilege:

• Part of the 2019 Capital One data breach that exposed the personal information of 106 million customers was caused by a firewall that had been given unauthorized access to data in cloud storage and the ability to conduct commands.
• Numerous data breaches in 2019 and 2020 compromised the private information of millions of people, and in one instance, 1.2 billion users. Because they lacked any type of access controls or password protection, cloud-based databases were accessible in all cases.
• During the Justdial data breach in 2019, about 100 million users’ personally identifiable information was exposed. Unauthenticated APIs were blamed for the breach because they provided attackers with uncontrolled access to the APIs’ back-end data.

Using the principle of least privilege also safeguards an organization from its own users, who are actually its own users. Overly privileged users have the potential to endanger the organization’s data or other assets through mistakes, carelessness, or malicious intent on the part of a vindictive insider. It is possible to prevent endpoints from becoming infected with malware or ransomware and, as a result, lessen the likelihood that it will spread throughout the company by restricting users’ access to install or run unauthorized apps.

The General Data Protection Regulation (GDPR), the Payment Card Industry Data Security Standard (PCI DSS), HIPAA, the Sarbanes-Oxley Act in the United States, and other legal obligations must all be complied with by numerous firms, depending on the sector or type of business. Organizations are better able to accomplish regulatory compliance and pass an audit when they correctly adopt and enforce the least privilege principle.

Best Practices for Least Privilege

• Use privileges with a time limit. Grant rights only long enough for a subject to carry out a given action, such as a user changing a password or, as previously indicated, a manager finishing a performance review, as much as feasible without interfering with an employee’s capacity to perform their job. Do the same for certain administrator tasks whenever possible to close the threat window.
• Disable unnecessary components. Remove or disable all superfluous services, which are frequently enabled and operating by default at startup, while configuring new systems or applications. You won’t be in danger if those components ever turn out to have flaws.
• Regularly review the logs. If possible, review logs every day. Log and monitor all authorizations and authentications to crucial systems. Automated systems can summarize routine events and notify you of anything out of the ordinary. You should keep an eye out for both successful and unsuccessful login attempts as well as any form of access control modifications, such as recently updated firewall rules or user accounts that were added without prior management approval.
• Review accounts and privileges on a regular basis. Review privileges at least once every three months, or more frequently if practicable. Make certain that active accounts have the minimal privileges necessary, revoke any extra privileges, and correctly terminate any old or inactive accounts. Regular review reduces “privilege creep,” which frequently happens when teams reorganize or people switch roles and subjects hold onto privileges they no longer require. A firewall with pages and pages of outdated, project-specific rules that have never been cleaned up is a typical nonuser example.
• Adopt “least privilege as default.” Surprisingly, many organizations do not sufficiently enforce this idea, despite the fact that it should be the default mindset for all security professionals given how essential it is. Nearly two-thirds of businesses had 1,000 or more files open to every employee, and 39% of businesses had more than 10,000 “stale but enabled” user accounts, both of which unnecessarily enhance the attack surface, according to a data risk analysis of nearly 800 businesses. Start with role-based access control, which bases users’ privileges on their job or assigned task, if you aren’t employing the least privilege and aren’t sure where to start.
• Apply relevant security principles. The principle of least privilege, together with the concepts of need to know and separation of duties, refines the privileges offered to subjects, further lowering risk.
• Specify a maximum cap on privileged accounts. Limit system administrators to the fewest number necessary, preferably less than 10% of total users, as attackers usually target these accounts due to their nearly unrestricted access. Any further raises the risk and the amount of effort necessary to oversee and keep track of records. Additionally, only provide regular users local administrator privileges in emergency situations.

Take Home

Although information security is a complicated, diverse subject, as indicated in the introduction, companies should, at the very least, make an effort to adhere to fundamental security principles and recognized best practices. By supporting the CIA triad and minimizing the attack surface, the principle of least privilege aids organizations in fortifying their defenses and lowering their total risk.