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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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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Linux audit log: dealing with audit.log file

Linux audit log: dealing with audit.log file The Linux kernel audit framework consists of several components including a daemon, control client, audit rules and Linux audit log. In this article we take additional measures to protect the audit.log file. Aureport The first useful utility to parse the audit.log is aureport. Without parameters it will give a summary of all events. This includes the files, users, audit keys and also items like suspicious events (anomalies). Each sub item can be read […]

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Lynis for Auditors: Linux and Unix auditing

Lynis for Auditors: Linux and Unix auditing Auditing on Linux Although Unix and Linux based systems are not new, getting an extensive knowledge of the operating system takes years of practice. Even then, with all changes it might be hard to keep up, especially when being an auditor. Examples of these are the differences between package managers, the way services are started and where binaries or configuration files are located. But no worries, there is help! Why Lynis? The goal […]

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Conducting a Linux Server Security Audit

Conducting a Linux Server Security Audit Auditing a system can be a time-consuming job, which is no different when conducting a Linux server security audit. Within this article, we give some highlights regarding the audit and tips to automate them by using Lynis. The business goal Before auditing any system, determine the business goal of the system. How critical is this system for doing business? What if the system goes down? Usually each system has a clear role or multiple […]

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What is a security audit?

What is a security audit? In the world of compliance, reported break-ins on the news and many security incidents, it’s common to see a security audit showing up sooner or later. Still, many people in our field don’t like them. But what is a security audit and why should we actually embrace them? Why audit? Auditing has a simple goal: check if something is configured according to best practices, a baseline or a preferred state. In an ideal situation these […]

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FreeBSD hardening with Lynis

FreeBSD hardening with Lynis Lynis development has its roots on a FreeBSD system, therefore FreeBSD hardening is also easy and supported when using Lynis. People who want to audit and harden their FreeBSD system will discover Lynis to be a powerful tool for this purpose. In this article we will focus on how to audit your system with Lynis. Lynis Lynis is an open source audit tool. It only requires root access and a normal shell and the tool is […]

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Configuring and auditing Linux systems with Audit daemon

Configuring and auditing Linux systems with Audit daemon The Linux Audit Daemon is a framework to allow auditing events on a Linux system. Within this article we will have a look at installation, configuration and using the framework to perform Linux system and security auditing. Auditing goals By using a powerful audit framework, the system can track many event types to monitor and audit the system. Examples include: Audit file access and modification See who changed a particular file Detect […]

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CAATTs for Linux: Lynis

CAATTs for Linux Within the field of the audit profession the usage of CAAT (Computer-assisted audit techniques) or CAATTs (computer-assisted audit tools and techniques) is growing. Lynis is filling this gap for Linux and Unix based systems. It’s a well-known and stable tool in this area and improves the audit process by automation. Only a few items could then be checked manually. This saves time, makes the audit more predictable and increases the quality of the overall audit. Lynis Based […]

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Auditing Linux: Software Packages and Managers

Auditing Linux: Software Packages and Managers No system can do its job without any installed software packages. However after installation of the system, or running it for a while, it often becomes unclear why some software was ever installed. This article looks at methods on auditing installed software, check for security updates and the related follow-up. Package managers To enable system administrators to properly manage software and upgrading them, Linux uses a package manager. This suite often consists of a […]

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Securing Linux: Audit with Lynis (an introduction into auditing)

Introduction Securing a Linux system can take a lot of time. For this purpose we have written Lynis, a quick and small audit tool. It’s an open source tool and freely available. You just need root permissions and a common shell and you’re ready to do your first audit. The main audience for this tool is auditors, security professionals, penetrating testers and system administrators. First audit Most Linux distributions already have Lynis in their software repository. If not, then download Lynis […]

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Linux Audit: Auditing the Network Configuration

Introduction Within this article we have a look on how to audit and check the network configuration of Linux and other systems. The main focus is on gathering information and discover how systems are configured. By taking these steps we will do a manual audit. For efficiency reasons we suggest to use an automated tool like Lynis. Where to start? Each Linux distribution has their own way and files to configure the network. Therefore we look at the basic components […]

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