Kali Linux Tutorials

We are excited to announce this major release of auditing tool Lynis. Several big changes have been made to core functions of Lynis. These changes are the next of simplification improvements we made. There is a risk of breaking your existing configuration.

Lynis is an open source security auditing tool. Used by system administrators, security professionals, and auditors, to evaluate the security defenses of their Linux and UNIX-based systems. It runs on the host itself, so it performs more extensive security scans than vulnerability scanners.

Supported OS

The tool has almost no dependencies, therefore it runs on almost all Unix-based systems and versions, including:

• AIX
• FreeBSD
• HP-UX
• Linux
• Mac OS
• NetBSD
• OpenBSD
• Solaris
• and others

It even runs on systems like the Raspberry Pi and several storage devices!

Installation Optional

Lynis is light-weight and easy to use. Installation is optional: just copy it to a system, and use “./lynis audit system” to start the security scan. It is written in shell script and released as open source software (GPL). 

How it works?

Lynis performs hundreds of individual tests, to determine the security state of the system. The security scan itself consists of performing a set of steps, from initialization the program, up to the report.

Steps

• Determine operating system
• Search for available tools and utilities
• Check for Lynis update
• Run tests from enabled plugins
• Run security tests per category
• Report status of security scan

Besides the data displayed on the screen, all technical details about the scan are stored in a log file. Any findings (warnings, suggestions, data collection) are stored in a report file.

Opportunistic Scanning

Lynis scanning is opportunistic: it uses what it can find. For example, if it sees you are running Apache, it will perform an initial round of Apache related tests. When during the Apache scan it also discovers an SSL/TLS configuration, it will perform additional auditing steps on that. While doing that, it then will collect discovered certificates so they can be scanned later as well.

In-depth security scans

By performing opportunistic scanning, the tool can run with almost no dependencies. The more it finds, the deeper the audit will be. In other words, Lynis will always perform scans which are customized to your system. No audit will be the same!

Use cases

Since Lynis is flexible, it is used for several different purposes. Typical use cases for Lynis include:

• Security auditing
• Compliance testing (e.g. PCI, HIPAA, SOx)
• Vulnerability detection and scanning
• System hardening

Resources used for testing

Many other tools use the same data files for performing tests. Since Lynis is not limited to a few common Linux distributions, it uses tests from standards and many custom ones not found in any other tool.

• Best practices
• CIS
• NIST
• NSA
• OpenSCAP data
• Vendor guides and recommendations (e.g. Debian Gentoo, Red Hat)

Lynis Plugins

Plugins enable the tool to perform additional tests. They can be seen as an extension (or add-on) to Lynis, enhancing its functionality. One example is the compliance checking plugin, which performs specific tests only applicable to some standard.