CMMC – Restrict Admin Privileges

This blog post “CMMC – Restrict Admin Privileges” is the tenth in a series on Cybersecurity Maturity Model Certification (CMMC) – a US Department of Defense (DoD) initiative that imposes requirements on contractors and subcontractors to help safeguard information within the US defense supply chain.

In this article, we look at how the ‘principle of least privilege’ (need to know) should be applied to your enterprise ICT systems to reduce the harm compromised accounts can cause and reduce the overall risks to information and business continuity.

Restrict admin privileges

The CMMC clearly explains how system administrators have the most privileged accounts on computer systems, so a malware infection or an account hijacking of that user could be catastrophic. For this reason, the Australian Cyber Security Centre (ACSC) has included ‘Restrict administrative privileges’ in the Essential Eight security controls; it is a critical step in achieving cyber resilience.

Anyone with an administrative account, whether for operating system activities or business application management, can directly access its configuration, the information within its datastores, and circumvent security controls.

Attackers use malware and brute force attacks to compromise administrative accounts since these accounts are the most powerful in your organisation. Once in the hands of an adversary, administrative accounts give the attacker the ability to do whatever they want. If you restrict the distribution of administrative privileges to those who need it and ensure they get only those privileges required to undertake the responsibilities of their job, you limit the harm these attacks can inflict. Furthermore, by restricting the rights associated with the account, malware has less opportunity to spread through the network, inhibited by the same constraints the account has.

ACSC has identified a number of approaches that, while they may appear to restrict administrative privileges, do not meet the intent of the strategy, and may even increase risk. First, simply  reducing the number of administrative accounts. While this certainly removes the number of accounts that an adversary can target, it is not a solution in itself.

The ACSC’s second point relates to shared non-attributable privileged accounts, meaning accounts that are used by more than one administrator.  With shared accounts, there is no way of knowing or finding out which logged in user did which action. If you use shared accounts, you lose your audit trail, and digital evidence in logs is no longer of value.

Two further approaches that ACSC suggests are not effective in restricting administrative privileges are temporarily allocating administrative rights to user accounts and placing standard user accounts in user groups with administrative privileges. The first of these has limited the time the account is exposed, but not the specific capabilities of the account, so a compromised user who is elevated to an administrator may still become infected, and the elevation will give the attacker those additional privileges too. Finally, putting users into groups with admin privileges creates the same problem as users being administrators, they are just getting the privileges from a different group. Instead, ACSC recommends you take a task-based approach to identify what activities administrators do and assigning only those privileges needed to do the job.

Furthermore, you should frequently check that the administrative accounts you created are correct and assigned to the most appropriate individuals. Accounts should be attributable only to the staff members to which they are assigned, and accounts should never be shared. If you want more information on secure administration, ACSC has created an excellent guide that you can access here.

The principle of Least Privilege

Taking the security control, restrict admin privileges to the next level, you can adopt a practical security architecture approach, known as the principle of least privilege. What this means is it provides system and user accounts only those privileges needed to perform their roles. A standard user account does not need to install applications so you can remove this privilege from that archetype’s capability. An account used for an application to log into a database does not require the ability to reset passwords or take backups, so remove those privileges. By doing this, you reduce the level of freedom attackers have when they compromise an account, thus minimising the harm they can inflict.

A secondary, not so security-related benefit is it improves your ICT systems’ stability by reducing the frequency by which users and administrators can make mistakes. If an administrator cannot accidentally delete a backup or a user cannot unwittingly delete a shared folder, your information availability is improved.

How security monitoring helps to restrict admin privileges

As we mentioned earlier, you must maintain individual accountability for all accounts, especially those with administrative privileges. You can boost your security posture further by implementing a solution for protective monitoring and alerting on the use and potential misuse of system privileges.

It’s possible to have your operating system report the use of privileges to event logs and record privilege changes so you can alert if more privileges are allocated, be that by mistake or as the result of an attack. Feeding events into a Security Information and Event Management (SIEM) system can afford the security team the ability to correlate events with user activities, so more in-depth investigations can take place, and root cause analysis can expose why certain things happened.

Gain visibility of security control effectiveness

Compliance is an issue for many organisations, so ensuring you remain in control of the distribution of privileges across your enterprise is vitally important. Huntsman Security has solutions that suit every business security need for managing system privileges. Our Next Generation SIEM with inbuilt Threat Intelligence and user entity and behavioural analytics can collect and alert on changes within your enterprise that could be indicative of an attack and immediately alert your security team.

Huntsman Security’s Essential 8 Scorecard and Essential 8 Auditor products monitor each of the eight controls recommended by ACSC. These platforms will alert you to issues with implementation, deviations from the compliance baseline and provide a current management level review of your security posture, suitable for an auditor to review as part of an external assessment.

Don’t wait for an attacker to expose and exploit your over-privileged accounts; take action today to reduce your attack surface and improve your security posture.

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