Home Blog The 10 Best Open Source SIEM Tools for Cybersecurity Experts

The 10 Best Open Source SIEM Tools for Cybersecurity Experts

January 06, 2022
cyber security expert using open source SIEM tools

In the ongoing battle against ransomware attacks, a Security Information and Event Management (SIEM) system helps organizations detect and build a defense much faster than regular IT teams can. Through a multi-layered approach, SIEM tools increase the chances of detecting a ransomware infection before it deploys, which gives your teams more time to identify to stop, remove, and repair any threat that comes their way.1

Keep reading to learn more about SIEM capabilities and our list of the best open source SIEM tools available today.

What is an Open Source SIEM?

In this modern era of cyber criminal behavior, businesses need defense plans as complex as the attacks they face. Following this approach, SIEM combines elements of Security Information Management (SIM) and Security Event Management (SEM) into a powerful, singular solution. Businesses use SIEM to protect themselves against cybersecurity threats like hacking, phishing, and ransomware, which have been surging in the past couple of years.1

The initial part of the SIEM solution, SIM, collects information in real-time via monitoring and analyzing log files and other network data. This is then fed into the SEM element of the solution, which helps cybersecurity experts visualize the data and respond to any incidents. To put it into perspective, SIEM has been compared to the central nervous system of the human body.2

A good SIEM solution will typically consist of several features, including log management, intrusion detection, asset discovery, data analysis, and vulnerability assessment. More powerful tools may have added features like compliance auditing, file integrity checks, event correlation, and app integrations.3

Open source SIEM tools are built with code that can be conveniently modified or altered by the user. This is often preferable for cybersecurity teams that need to customize code for it to work with their existing IT system. Open source platforms are also often free or cheaper due to their community-led development and support.

However, they often lack the power and functionality of professional SIEM tools built by industry-leading software developers. An open source system typically offers the best SIEM tools for small business users who don't require the high-level functionality preferred by enterprise corporations.4

10 Best Open Source SIEM Platforms

Below, we’ll discuss the top ten open source SIEM platforms and tools and the features that make them superior.

1. AlienVault OSSIM

AlienVault OSSIM is a popular open source SIEM platform that includes asset discovery, intrusion detection, event correlation, and behavioral monitoring.

The development team at AlienVault OSSIM is highly productive, providing frequent updates and support along with an active community forum. While OSSIM only requires a single server and can operate both locally and virtually, it has quite a complex installation process and limited flexibility.5

2. ELK Stack

Elastic Stack (ELK) is an advanced open source SIEM tool that’s ideal for businesses that use a wide variety of disparate IT systems. By incorporating various plugins, ELK can aggregate, correlate, and visualize data from multiple sources using embedded Logstash components.

However, setup is complex and users will need to develop manual security rules, making it a more bespoke solution for specific business cases.6

3. Graylog

Graylog is a relatively standard open source SIEM tool with the usual features, but it benefits from high scalability and a user-friendly interface. Tools include log collection, threat detection, notifications, and incident response.

With the customizable dashboard, you can tailor your inputs into simplified visualizations to make it more attractive to non-technical users. You also get built-in fault tolerance and multi-threaded searches.7

4. MozDef

Developed by the team behind the open source browser Firefox, MozDef stands for Mozilla Defense Platform. It runs on the AWS cloud and was inspired by and subsequently designed to directly combat the very tools used by cybercriminals to coordinate attacks.8


OSSEC is a somewhat limited open source incident management and response platform that works best in conjunction with other tools. However, it's worth a mention due to its powerful correlation and analysis engine.

Able to run on almost any operating system, OSSEC has an active support community, can operate in server-less mode, and boasts unique features like rootkit detection, policy enforcement, and registry monitoring.7

6. Prelude OSS

Prelude Open Source SIEM (OSS) is an agentless system that correlates and reports on events from multiple sources regardless of brand or license. Benefiting from native support and utilizing international standards for normalization, Prelude interacts well with third-party security tools.

Users can collect a wide variety of log files from any system for sorting, aggregation, and incident response. However, as a downgraded version of Prelude's main SIEM engine, Prelude OSS is best used in small environments like SMBs.9

7. Security Onion

As the name suggests, Security Onion uses a multi-layered system that contains both physical and network security, along with intrusion prevention, detection, and mitigation.

Powerful enough to operate in both an SMB or Enterprise environment, Security Onion is a free open-source SIEM tool built on Linux. It incorporates several other SIEM tools like Elasticsearch, Logstash, Wazuh, and Suricata.10

8. SIEMonster

SIEMonster is another open source SIEM that incorporates several third-party tools into one, easy-to-use platform. In addition to the standard logging, monitoring and analysis tools, SIEMonster benefits from machine learning, virtualization and human-based behavior correlation.

Although it does have a free version, the paid version is highly affordable and one of the most powerful SIEM tools available for SMBs or Enterprise organizations.11

9. Splunk Free

Splunk is an excellent security monitoring tool for small businesses, with the free version giving users limited access to test some of the powerful Enterprise features. These limits include 500MB a day of log file indexing with two bulk data loads per month. Features include dashboards, reports, indexing, powerful search functionality, and real-time alerts (Enterprise only).12

10. Wazuh

Wazuh is a user-friendly open source incident management and response platform that evolved from the OSSEC system. Now its own powerful standalone system, Wazuh features log analysis, intrusion detection, integrity monitoring, regulatory compliance, and cloud security.

With no vendor lock-in or license cost and professional support, Wazuh is a highly flexible enterprise-ready SIEM solution. In addition to the free version, there is a paid cloud version that centralizes threat detection and response across a distributed cloud environment.13

Learn How to Leverage Open Source SIEM Tools

If the power and flexibility of open source SIEM tools appeals to you, then a career in cybersecurity can get you in on the action. Companies around the world are beginning to understand how critical cybersecurity defense is in their daily operations, so they’re actively seeking cybersecurity professionals who can wield these SIEM tools and other modern defenses. When you graduate from the Online Master's in Cybersecurity program at Yeshiva Katz, you’ll be poised to fill those lucrative roles.

Explore our curriculum or talk to an advisor to get started.

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