However, not all companies are willing to make the necessary investments, and definitely, not all threats are viewed as equal. While company will most definitely employ basic security solutions, such as firewalls and anti-viruses, not everybody is makes the necessary investment into privileged account security and user action monitoring, with many opting for standard built-in measure that their software and systems provide. Linux in particular has the reputation for being less vulnerable to malware, but its privileged accounts are in fact very prone to both hacker attacks and misuse by malicious insiders. Let us look in more detail at how to control privileged user on Linux and what security measures Linux provides out of the box in order to help protect privileged accounts, and how effective they really are.
Types of Linux accounts
Same as Windows, Linux features several types of accounts:
Super user or root – this is a default administrative account that allows for a full control of the system akin to Windows Administrator account. Linux root privileges allow user to execute any commands and control any services and any other accounts, change user permissions, add user to group, etc. Normal user – this is a regular account with restricted set of Linux user privileges. It can’t access any critical system resources or services and needs permission from root user to run certain commands. System user – a user account with the same level of privilege as the normal user, reserved for the use by various applications. Such accounts are employed in order to give applications certain permissions, or to isolate them for security purposes.
Linux allows for great flexibility with its accounts. You can create multiple root Linux accounts if needed, and also assigned different permissions to accounts or groups of accounts. You can also directly change permissions for reading, writing and execution of certain files or directories, as well as their ownership, which directly dictates user’s authority over said files. All of this flexibility, however, is a double edged sword, making it easy for perpetrator or tech-savvy malicious insider to misuse or steal protected data. Ultimately, the root account is the most vulnerable point of the system as it is necessary for access to protected files and settings, and Linux has a couple of built-in ways to protect such an account.
Privileged Account Security
Any active root account should always be protected with a password, and Linux will ask you to set one during the installation or when you first decide to use root account. However, directly using root account is not the most secure course of actions for an organization, especially if you have several system administrators. Much better way is to use a regular account and temporarily enable root privileges, by using su or sudo commands. Both of these commands perform a similar task – allow to delegate administrative privilege to regular account, but they function slightly differently. In order to use su, your administrator needs to know both password from their own account and from the root. While this may provide additional layer of protection when their account is compromised, it is not ideal from the insider threat standpoint. Sudo command allows to get root privilege level without the need to know root password. Permission to access sudo command for other users is decided directly by the root. Sudo disables any additional privileges when the user stays inactive for more than five minutes, requiring password the next time, which helps to protect the console when administrator leaves without disabling privileged access. Overall, this basic security measures allow to limit the extent of power that administrator has over the system and allow to better track the usage of administrative accounts. For example, if the administrator has logged in at an unusual time, it may be a cause for concern over breach or insider attack. However, without the proper insight into user actions, reliable protection from insider attacks cannot be guaranteed. Let us look at what tools Linux provides in user monitoring department.
Built-in Linux Monitoring Tools
Linux has a number of commands that allow privileged users to access logs and monitor the use of various system resources. The most basic of them is the top tool that provides a dynamic overview of all currently running processes. You can not only check system resource utilization, but also see all executed commands and other useful information that can give you some insight into what your users are doing. Linux is also famous for its built-in network sniffer. Unlike the similar Windows tool, it allows not only to view network traffic in real time, but also capture it for later analysis, which provides a good amount of visibility into network usage. Overall, Linux has fairly robust built-in monitoring functionality, but it is designed mainly for technical maintenance and troubleshooting. It does not present data in a convenient manner, and does not allow to easily get an overview of user actions, which makes its usefulness for insider threat detection fairly limited. While Linux has a number of built-in tools for controlling and protecting privileged accounts, in a modern cybersecurity environment this level of protection is not nearly enough. New threats and vulnerabilities emerge very time, and Linux is not immune from them. If you wish to truly protect your Linux system, you need to employ a professional privileged access management and privileged user monitoring solutions that will give you a full visibility into who logged in with a privileged account and what they are doing.
