Anatomy of Security-Enhanced Linux (SELinux)

Linux® has been described as one of the most secure operating systems available, but the National Security Agency (NSA) has taken Linux to the next level with the introduction of Security-Enhanced Linux (SELinux). SELinux takes the existing GNU/Linux operating system and extends it with kernel and user-space modifications to make it bullet-proof. If you're running a 2.6 kernel today, you might be surprised to know that you're using SELinux right now! This article explores the ideas behind SELinux and how it's implemented.

SELinux blocks real-world exploits

Linux security experts are reporting a growing list of real-world security situations in which the US National Security Agency's SELinux security framework contains the damage resulting from a flaw in other software. These so-called "mitigations" are showing that a Linux feature that began as an esoteric security measure is starting to prove its worth.

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Mambo Exploit Blocked by SELinux

If you operate Internet-connected servers, chances are you eventually will have to deal with a successful attack. Last year, I discovered that despite the multilayered defenses in place on a test Web server (targetbox), an attacker had managed to use an exploit in a partially successful attempt to gain access. This server was running Red Hat Enterprise Linux 4 (RHEL 4) and the Mambo content management system. It had multiple defenses in place, including Security-Enhanced Linux (SELinux). SELinux prevented the attacker from executing the second stage of the attack, possibly preventing a root compromise.

This article presents a case study of the intrusion response, explaining how I discovered the intrusion, what steps I took to identify the exploit, how I recovered from the attack and what lessons I learned regarding system security.

A step-by-step guide to building a new SELinux policy module

Who’s afraid of SELinux? Well, if you are, you shouldn’t be! Thanks to the introduction of new GUI tools, customizing your system’s protection by creating new policy modules is easier than ever. In this article, Dan Walsh gently walks you through the policy module creation process.