What Is a Superuser?

A superuser is a user account with the highest level of access and privileges within a system or software application. Depending on the role and responsibility associated with a user account, the account has different abilities and restrictions.

The National Institute of Standards and Technology (NIST), an agency of the US Department of Commerce, says a superuser has the authority to “perform security-relevant functions that ordinary users are not authorized to perform” [1].

Besides security operations, a superuser account can also have administrative privileges including:

• Read from and write to file systems

• Govern all facets of user account settings

• Install essential software and hardware 

• Revise security settings

Superuser accounts in different operating systems

A superuser’s moniker may differ depending on the operating system. The following list covers Windows, Linux, and macOS.

• Windows: Windows commonly refers to a superuser account as the “administrator account.” With this account, you have complete administrative control over the system and can install software and hardware, modify security settings, and more.

• Linux: Linux and other Unix-like systems, such as Ubuntu, call the superuser account the “root.” Unix’s “sudo” function lets you temporarily gain superuser-level permissions, allowing you to carry out administrative tasks without permanently switching to the root account.

• macOS: Built on Unix, macOS also calls the superuser account “root.” When the root modifies files on a Mac, you have to reinstall macOS to undo those changes.

Considering the vast access privileges of a superuser account, you need to understand its security implications for businesses and federal organizations.

For instance, Edward Snowden, a former IT contractor at the National Security Agency (NSA), used his superuser privileges to leak classified NSA files. The federal entity responded by slashing its system administrators by 90 percent [2].

5 ways to strengthen superuser account security

Here are some tips you can use to mitigate the risks of account misuse or unauthorized access to superuser accounts:

1. Restrict superuser membership.

Rather than granting superuser rights to several users, adopt a strategy that allows temporary access to privileges. For example, in Unix and Linux systems, the sudo (superuser do) command gives selective privileges to regular accounts.

2. Subdivide systems and networks.

Use system and network segmentation by dividing users and processes into separate groups based on specific requirements and privilege levels. Doing so helps you effectively manage access. In turn, it can also reduce the negative effects of potential security breaches or unauthorized actions.

3. Create a strong password.

Aim to create a password that is not only unique but also difficult to guess. Using a varied combination of capital and small letters, special characters, and numbers can strengthen the root/administrator password.

4. Regularly change the superuser’s password.

Regular password changes, including after each use, can drastically reduce security risks associated with superuser accounts. A two-factor authentication (2FA) or multifactor authentication (MFA) adds additional security measures to better safeguard superuser accounts.

5. Scan for unsuccessful password attempts.

Enforce an account lockout policy to automatically disable superuser accounts after a certain number of failed password attempts within a defined timeframe. This security measure can significantly decrease the likelihood of brute-force attacks.

Related terms

• System administrator

• Network administrator

• Database administrator

• Salesforce Administrator

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