Passionate about Linux hardening, compliance, security management and new technologies.

Lynis Security Notice: 1.5.4 and older

Lynis Security Notice: 1.5.4 and older This week a vulnerability was reported in versions up to Lynis 1.5.4. With Lynis being a security audit tool and focused on hardening Linux and Unix based systems, we regret any (security) bug being discovered. Since it is open source software, we like to be open about the issue, to help you understanding it and take the right precautions. Description: The temporary files created in the tests_webservers section are too predictable. This may resulting […]

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Auditing Linux processes: The Deep Dive!

Auditing Linux processes From the initial start of the Linux operating system, the first processes are already born. In this article we have a look on dealing with processes. In particular we look at how to do process auditing. Whenever you are an auditor, system administrator or just a Linux enthusiast, you can’t ignore processes and should know how to deal with them. Process listing For most people working on Linux systems, it might be obvious to display running processes […]

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Audit SSH configurations: HashKnownHosts option

Audit SSH configurations: HashKnownHosts option How it works Each time the SSH client connects with a server, it will store a related signature (a key) of the server. This information is stored in a file names named known_hosts. The known_hosts file itself is available in the .ssh subdirectory of the related user (on the client). In the case the signature of the server changes, SSH will protect the user by notifying about this chance. Risk involved This configuration option is […]

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Linux system hardening steps to improve security

System hardening for Linux desktops and servers Most systems have confidential data that needs to be protected. To safeguard this data, we need to secure our Linux system. But how to properly harden a Linux system? In this article, we will cover this step by step. We start by with physical security measures to prevent unauthorized people from access the system in the first place. Next is doing the installation the right way, so we have a solid foundation. Finally, […]

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How to keep Lynis up-to-date?

How to keep Lynis up-to-date? Keeping software like Lynis up-to-date is nowadays very important. More and more vendors implement software development methodologies like agile and scrum, to decrease the time between new software versions. This way software enhancements are easier to implement and possible bugs earlier fixed. It’s up to the user of the software to stay up-to-date and therefore we provide some tips on how to update Lynis easily. Notifications Staying up-to-date begins with receiving an update when a […]

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Unix security audit: Perform an audit in 3 minutes

Unix security audit: Perform an audit in 3 minutes Want to know the vulnerabilities of a Unix/Linux system is in just 3 minutes? How? Perform a scan with Lynis, the open source Unix security audit tool! Lynis Lynis is open source software (GPLv3), released in 2007 and a popular choice by many security professionals and system administrators. Hundreds of downloads in the first week of each release and with a lot of community feedback, Lynis is the right tool for […]

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Become a Linux Auditor: What to know?

Linux Auditor: What to know? Now open source software and platforms are very common, the need for knowledge in this area is increasing. Becoming a technical auditor with specialized knowledge about Linux, might be a clever move. Technical When specializing in Linux, the auditing area is already more technically oriented, instead of the processes. A true Linux auditor knows more than the basics of Linux. In-depth knowledge is required, like what file systems are common, how permissions are arranged, popular […]

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Auditing Linux: what to audit?

Auditing Linux: what to audit? In this article we answer the big question on Linux systems “what to audit?”. Where do you start and what is useful to audit? We apply our three C‘s in this article to determine what we should look for when auditing a Linux system. Current state What is the current state of the system and how does it compare to previous time? Ideal situation: compare current state of the system with a predefined baseline or […]

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Central audit logging: Configuration and collecting of Linux audit events

Central audit logging: Configuration and collecting Linux audit events This guide is to help our users of the Lynis Enterprise Suite to configure a central node to receive Linux audit events. It provides some pointers on how to do a quick set-up, to store and forward events. This information is very valuable for forensic investigations and intrusion detection. Configure the server First start by configuring the server. Since this is a central log host, it should have enough disk capacity […]

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Become a Linux auditor: tips to start with auditing the Linux platform

Become a Linux auditor: tips to start with auditing the Linux platform This guide helps people new to the Linux platform to get a grasp on how the system works. Whenever you are an IT auditor, or simply want to know more about the basics, this guide helps you in determining where to start an audit. Processes Each operating system consists of smaller running processes. In case of Linux this is true as well and can be displayed with the […]

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How to: Using Lynis plugins

How to: Using Lynis plugins Within this “how to” we explain when and how to use Lynis plugins. What are plugins? Plugins are small extensions to an existing program. Also Lynis supports the use of external plugins to extend functionality. Lynis plugins are written in shell script and might use system binaries or external binaries to perform additional checks. The big difference between custom tests and plugins in Lynis, are the goal of the tests. If some logic function checks […]

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Linux Audit Framework: using aureport

Linux Audit Framework: using aureport The Linux audit framework logs events, as specified by the configured watches. To extract particular events we can use the ausearch or aureport tools. The latter is the one we will focus on in this article, to get the most out of the tool. Aureport The aureport utility can be executed without any parameters. It will then extract all audit events available from the log. Since the audit log can be very big, it might […]

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