Linux Endpoint Detection and Response (EDR) is a set of security techniques for searching possible threats in the system endpoints by monitoring and detecting suspicious behavior (like the EDR) but intended for systems with Linux as the operating system.

In this context, an endpoint is any device that has a distinct identity on the network. Endpoints include physical PCs and servers, virtual machines, mobile devices, and even IoT devices. Essentially, if you can connect something to the network, it’s an endpoint.

Keep reading for a look at how Linux EDR works, which types of threats it can (and can’t) defend against, and what role Linux EDR plays within a broader cybersecurity strategy.

What is EDR?

As it was mentioned before, Linux EDR is based on EDR but intended for Linux operating systems, then the characteristics between both are shared.

Which security risks can be detected?

By monitoring endpoints, it’s possible to detect and respond to a variety of security threats and risks, including:

• Malware. Malicious software that attackers manage to install on a target system. Malware can often be detected by looking for unusual system processes or network connections.
• Vulnerabilities inside software applications or packages, which EDR tools can scan to look for known vulnerabilities.
• Cryptojacking software, whose presence may be revealed by unusual network protocols or connection patterns.
• Malicious insiders, whose activity within a system can be monitored using EDR to detect actions like deletion or copying of important data.
• Compromised user accounts, which EDR tools can identify by looking for unusual account activity.

The list could go on, but these are some of the most common types of security issues that EDR excels at detecting.

Benefits of EDR

EDR is a pillar of modern cybersecurity because EDR helps to detect risks within one of the most important types of resources that exist in a modern IT estate – endpoints.

If your endpoints are breached, any workloads hosted on those endpoints – such as applications or data stored locally – are at risk. In addition, a breached endpoint can serve as a beachhead that attackers use to escalate a breach into other endpoints, so detecting endpoint risks early helps to minimize the impact of attacks.

Limitations of EDR

It’s important to note that EDR is subject to major limitations:

• It only works for endpoints, so it’s not useful for protecting other types of resources – such as APIs – that aren’t linked to a specific endpoint.
• EDR requires you to be able to access basic logs and metrics from your endpoints, which isn’t always possible. For example, if you use Functions-as-a-Service in the cloud, you typically don’t have access to endpoint data, so you can’t use EDR to help secure your workloads.
• It’s possible for sophisticated attacks to evade EDR detection techniques. For example, well-designed malware may obfuscate itself by operating as a process designed to look legitimate, making it hard for EDR tools to detect the risk.

For these reasons, EDR should be only one component of a modern cybersecurity strategy. EDR provides critical foundational protection against many types of threats, but it doesn’t cover every potential risk that may exist.

What is Linux EDR?

Linux Endpoint Detection and Response is the use of EDR practices to protect Linux-based servers, PCs, and other devices.

Linux EDR is similar in most ways to EDR for other types of endpoints, in the sense that Linux EDR focuses on analyzing data from endpoint environments to detect risks. However, the main distinguishing characteristic of Linux EDR is the type of data sources that Linux EDR tools rely on.

Although there is some variation between the types of data that different Linux distributions process, almost all Linux systems generate the same core types of data that EDR solutions can monitor:

• Syslog, a central log file on each Linux endpoint that records operating system and application events.
• Auth.log, a log file that records authentication events.
• Cron.log, which records events associated with cron, a tool on Linux systems that runs processes or commands on a recurring, pre-scheduled basis.
• Logs generated by package management software that record software installation, uninstallation, and update events. (The exact log files vary depending on which package manager a Linux system uses.)

Linux systems include a variety of other log files that could be used for EDR purposes, but the ones we just described represent the most important log files for Linux EDR.

In addition to log files, Linux EDR solutions can monitor a variety of other data sources for security-relevant information, such as:

• Which processes are running.
• Which network ports are open and which hosts are connected to them.
• Which user and group accounts exist on the system and which permissions they have.
• File system access control permissions.
• Which commands each user has run.

By continuously analyzing these data sources and correlating the sources with each other where necessary, it’s possible to identify many types of security threats that could impact Linux-based endpoints.

Linux EDR examples

To understand what Linux EDR means in practice, let’s look at a few examples of security threats that it can help to detect.

Malicious insider detection

Imagine that a disgruntled employee has decided to delete critical data that is stored on a Linux server in order to cause harm to the company. To do this, the employee (who already has an account on the server) logs in and runs a command like the following:

rm -rf /path/to/critical/data

This command tells Linux to delete the data. By monitoring activity on the server, a Linux EDR solution could detect this command (or the sudden disappearance of the data) and flag it as unusual. It could then alert engineers to the activity so that they could recover the data from a recent backup before the backup is overwritten.

Malicious access attempts

As a variation of the scenario just described, imagine that the disgruntled employee has been barred from accessing a particular server by having her account deleted. However, the employee, still bent on wreaking havoc, decides to try to log into the server by bruteforcing the password for another user’s account. Bruteforcing means that she cycles through different password combinations repeatedly in order to try to log in.

By continuously monitoring the server’s auth.log file, a Linux EDR tool would detect the recurring failed login attempts, revealing the suspicious activity.

Malware detection

As a final example of Linux EDR, imagine an employee who uses a Linux-based PC, and who has been tricked via a phishing email into installing a malicious application on the PC.

If a Linux EDR tool is set up to monitor software installation events, it will likely flag the installation of the malware. And even if EDR tools aren’t monitoring package installation logs (or if the malware is installed without using packages), they would also likely be able to identify the malware once it is running by detecting a new and unusual process, or by monitoring syslog for unusual events.

Through this monitoring, the tools would be able to alert engineers to the potential malware so they could respond before a major breach occurs.

Conclusion

If your IT environment includes Linux endpoints – whether they’re servers, PCs, or even IoT devices – Linux EDR is an essential part of your cybersecurity arsenal. Linux EDR helps to detect various types of threats so that you can respond proactively before Linux-based systems are compromised.