Security Onion

Our "Security Onion Fundamentals for Analysts and Threat Hunters" class will be running Tuesday April 21, 2026 through Friday April 24, 2026 in Colorado Springs, CO. Use the following code before January 31, 2026 to get 10% off!

earlybird

For more info and to register, please visit https://securityonionthapr2026.eventbrite.com/.

For a list of our upcoming public classes, please visit https://securityonionsolutions.com/training/#public-training.

Wednesday, December 24, 2025

Security Onion Documentation printed book now updated for Security Onion 2.4.200!

We've been offering our Security Onion documentation in book form on Amazon for a few years and it's now been updated for the recently released Security Onion 2.4.200!

Thanks to Richard Bejtlich for writing the inspiring foreword!

Proceeds go to the Rural Technology Fund!

This edition has been updated for Security Onion 2.4.200 and includes a 20% discount code for our on-demand training and certification!

This book covers the following Security Onion topics:

First Time Users
Getting Started
Security Onion Console (SOC)
Security Onion Desktop
Network Visibility
Additional Network Visibility
Host Visibility
Third Party Integrations
Rules
Logs
Updating
Accounts
Services
Customizing for Your Environment
Tricks and Tips
Utilities
Help

Q&A

What is the difference between this book and the online documentation?

This book is the online documentation formatted specifically for print. It also includes an inspiring foreword by Richard Bejtlich that is not available anywhere else! Proceeds go to the Rural Technology Fund! Finally, the printed book includes a 20% discount code for our on-demand training and certification.

Who should get this book?

You should get this book if you work on airgap networks or simply want a portable reference that doesn't require an Internet connection or batteries! Also anyone who wants to donate to a worthy cause like Rural Technology Fund!

What is the difference between this edition and the previous edition?

This edition has been updated for Security Onion 2.4.200!

Where do we get it?

https://securityonion.com/book

Friday, December 19, 2025

Early Bird Discount for Upcoming Security Onion Training Class

Our popular "Security Onion Fundamentals" class will be running Tuesday April 28, 2026 through May 1, 2026 in Alpharetta GA. Use the following code before January 31, 2026 to get 10% off!

earlybird

For more info and to register, please visit https://securityonionapr2026.eventbrite.com.

For a list of our upcoming public classes, please visit https://securityonionsolutions.com/training/#public-training.

Tuesday, December 16, 2025

Security Onion 2.4.200 now available with Major Improvements for our Onion AI Assistant!

Security Onion 2.4.200 is now available and includes several new features, updated components, and many quality of life improvements!

For Security Onion Pro customers, we've made major improvements for our popular new Onion AI Assistant!

Onion AI is a huge leap forward in leveraging AI to assist you in triaging alerts, working incidents, and tuning your deployment!

Here are some of the improvements for Onion AI in this release:

make Onion AI more accurate and curious
add tool for creating / updating / disabling / enabling detections
escalate to existing case
auto compact context support
additional UI metrics
add option to use EU region instead of US for Onion AI
add QWEN 235B as a lower cost option for an Onion AI model (please note that this model was trained in China but is hosted in your local AWS region and no data is logged)

https://docs.securityonion.net/en/2.4/assistant.html

IDSTools Replacement

For the last few years, we've used IDSTools to manage NIDS rulesets. In this release, we've removed IDSTools and moved this functionality into Security Onion Console. If you use the standard ETOPEN ruleset, then all migration should happen automatically.

WARNING! If you have any custom Suricata rulesets, then all Suricata detection syncing will be blocked. For more information and required steps, see the Sync Block section of the documentation:

https://docs.securityonion.net/en/2.4/nids.html#syncblock

We highly recommend that you test this on a test deployment before you deploy to production!

Resolved Security Issue

On 12/14/2025, we were notified of a Remote Code Execution (RCE) vulnerability under certain circumstances. When joining a node to a distributed deployment, a file called install.txt is transferred from the node to the manager and then processed. An attacker can leverage this processing to achieve remote code execution on the manager. To do so, they must first have root access to the node to modify install.txt since it is only writable by root by default. If this is a new node that has not connected to the manager before, then it would be blocked by the manager's firewall by default. Allowing the traffic through the manager's firewall would require either root access to the manager or superuser rights in SOC. Once the traffic is allowed through, the salt minion running on the new node would have to be accepted by the manager which also requires superuser rights in SOC.

The fix for this issue is to ignore control characters in the install.txt file and that has been implemented in this release.

Timeline

12/14/2025 - responsible disclosure

12/15/2025 - merged fix

12/16/2025 - Security Onion 2.4.200 released including fix

Thanks to Ashlen for the responsible disclosure!

Updated Components

This release updates several components including:

Saltstack to 3006.16
Strelka to 1.0.1
Suricata to 8.0.2
Zeek to 8.0.4

With the upgrade to Suricata 8, our recommended full packet capture utility is now Suricata. Stenographer will be removed next year so if you haven't already transitioned from Stenographer to Suricata PCAP then now is the time to do so:

https://docs.securityonion.net/en/2.4/suricata.html#switching-pcap-from-stenographer-to-suricata

Release Notes

There are many more features and fixes included in this release! For a complete list of all changes, please see the Release Notes:

https://docs.securityonion.net/en/2.4/release-notes.html#changes

Known Issues

If you haven't viewed cases in a while, escalating from Onion AI to an existing case will fail.

For a list of known issues, please see:

https://docs.securityonion.net/en/2.4/release-notes.html#known-issues

About Security Onion

Security Onion is a free and open platform built by defenders for defenders. It includes network visibility, host visibility, intrusion detection honeypots, log management, and case management.

For network visibility, we offer signature based detection via Suricata, rich protocol metadata and file extraction using your choice of either Zeek or Suricata, full packet capture, and file analysis. For host visibility, we offer the Elastic Agent which provides data collection, live queries via osquery, and centralized management using Elastic Fleet. Intrusion detection honeypots based on OpenCanary can be added to your deployment for even more enterprise visibility. All of these logs flow into Elasticsearch and we’ve built our own user interfaces for alerts, dashboards, threat hunting, case management, and grid management.

Security Onion has been downloaded over 2 million times and is being used by security teams around the world to monitor and defend their enterprises. Our easy-to-use Setup wizard allows you to build a distributed grid for your enterprise in minutes!

Documentation

You can find our online documentation here:

https://docs.securityonion.net/en/2.4/

Documentation is always a work in progress. If you find documentation that needs to be updated, please let us know as described in the Feedback section below.

New Installations

If this is your first time installing Security Onion 2.4, then we highly recommend starting with an IMPORT installation as shown at:

https://docs.securityonion.net/en/2.4/first-time-users.html

Once you’re comfortable with your IMPORT installation, then you can move on to more advanced installations as shown at:

https://docs.securityonion.net/en/2.4/architecture.html

Existing 2.4 Installations

If you have an existing Security Onion 2.4 installation, you can update to the latest version using soup:

https://docs.securityonion.net/en/2.4/soup.html

Before updating your production deployment, we highly recommend testing the upgrade process on a test deployment that closely matches your production deployment if possible. This is especially important for releases that update components like Salt and Elastic.

2.3 EOL

As a reminder, Security Onion 2.3 reached End Of Life (EOL) on April 6, 2024:

https://blog.securityonion.net/2023/10/6-month-eol-notice-for-security-onion-23.html

Thanks

Lots of love went into this release!

Special thanks to all our folks working so hard to make this release happen!

Josh Brower
Jason Ertel
Corey Ogburn
Josh Patterson
Mike Reeves
Jorge Reyes
Matthew Wright

Questions, Problems, and Feedback

If you have any questions or problems, please create a new Discussion at:

https://securityonion.net/discuss

Security Onion Pro

We recently celebrated 10 years in business by announcing Security Onion Pro:

https://blog.securityonion.net/2024/07/celebrating-10-years-of-security-onion.html

Security Onion Pro includes many enterprise features that folks have been asking for:

Active Query Management
External API
Open ID Connect (OIDC)
Data at Rest Encryption
FIPS for the OS
DoD STIG for the OS
External Notifications in SOC
Time Tracking inside of Cases
Guaranteed Message Delivery
Manager of Managers
MCP Server
Security Onion App for Splunk
Hypervisor
Reports
Onion AI Assistant

You can read more about these enterprise features at:

https://securityonion.com/pro

Training

Need training? Start with our free Security Onion Essentials training and then take a look at some of our other official Security Onion training!

https://securityonion.net/training

Security Onion Solutions Hardware Appliances

We know Security Onion's hardware needs, and our appliances are the perfect match for the platform. Leave the hardware research, testing, and support to us, so you can focus on what's important for your organization. Not only will you have confidence that your Security Onion deployment is running on the best-suited hardware, you will also be supporting future development and maintenance of the Security Onion project!

https://securityonion.com/hardware

Cloud Installations

For new Security Onion 2 installations in the cloud, this new version will soon be available on the AWS, Azure, and GCP marketplaces!

AWS Marketplace and Documentation:

https://securityonion.net/aws/?ref=_ptnr_soc_blog_251216

https://docs.securityonion.net/en/2.4/cloud-amazon.html

Azure Marketplace and documentation:

https://securityonion.net/azure

https://docs.securityonion.net/en/2.4/cloud-azure.html

GCP Marketplace and documentation:

https://securityonion.net/google

https://docs.securityonion.net/en/2.4/cloud-google.html

Monday, November 3, 2025

Security Onion Documentation printed book now updated for Security Onion 2.4.190!

We've been offering our Security Onion documentation in book form on Amazon for a few years and it's now been updated for the recently released Security Onion 2.4.190!

Thanks to Richard Bejtlich for writing the inspiring foreword!

Proceeds go to the Rural Technology Fund!

This edition has been updated for Security Onion 2.4.190 and includes a 20% discount code for our on-demand training and certification!

This book covers the following Security Onion topics:

First Time Users
Getting Started
Security Onion Console (SOC)
Security Onion Desktop
Network Visibility
Additional Network Visibility
Host Visibility
Third Party Integrations
Rules
Logs
Updating
Accounts
Services
Customizing for Your Environment
Tricks and Tips
Utilities
Help

Q&A

What is the difference between this book and the online documentation?

Who should get this book?

What is the difference between this edition and the previous edition?

This edition has been updated for Security Onion 2.4.190!

Where do we get it?

https://securityonion.com/book

Security Onion Conference 2025 Recordings Now Available!

Friday, October 31, 2025

Spooky malware analysis!

It's October 31, so let's analyze some spooky malware!

Thanks to Brad Duncan for sharing this pcap from 2025-10-08 on his malware traffic analysis site! Due to issues with Google flagging a warning for the site, we're not including the actual hyperlink but it should be easy to find.

We did a quick analysis of this pcap using Security Onion 2.4.190:

https://blog.securityonion.net/2025/10/security-onion-24190-now-available.html

If you'd like to follow along, you can do the following:

install Security Onion 2.4.190 in a VM:
https://docs.securityonion.net/en/2.4/first-time-users.html
import the pcap using the SOC Grid interface:
https://docs.securityonion.net/en/2.4/grid.html#icons-in-lower-left-corner
optionally enable the DNS lookups feature:
https://docs.securityonion.net/en/2.4/soc-customization.html?#reverse-dns-lookups

The screenshots at the bottom of this post show some of the interesting alerts and their associated AI Summaries and Guided Analysis. Keep in mind that this is not some contrived demo, we simply downloaded a recent malware PCAP from Brad Duncan's site and imported it into Security Onion. Also keep in mind that this was just a PCAP and so there was no endpoint data. Had there been endpoint data, the results would have been even more in-depth.

Want more practice? Check out our other Quick Malware Analysis posts at:

https://blog.securityonion.net/search/label/quick%20malware%20analysis

About Security Onion

Security Onion is a versatile and scalable platform that can run on small virtual machines and can also scale up to the opposite end of the hardware spectrum to take advantage of extremely powerful server-class machines. Security Onion can also scale horizontally, growing from a standalone single-machine deployment to a full distributed deployment with tens or hundreds of machines as dictated by your enterprise visibility needs. To learn more about Security Onion, please see:
https://securityonion.net

Screenshots

Let's start with an overview of all logs generated by Security Onion:

Now let's look at just the alerts sorted by severity:

Next we'll drill into the high severity alerts and review the AI Summaries and AI Playbooks:

Here's the second high severity alert:

And the third high severity alert:

And the fourth high severity alert:

All of the above can be done with our standard free version.

Now let's look at our new Onion AI feature available for Security Onion Pro customers. First, we ask Onion AI to summarize the activity in the date range:

(Onion AI response continued):

We can then ask Onion AI to investigate the traffic to non-standard ports:

(Onion AI response continued):

Next, we ask Onion AI to investigate specific high severity alerts starting with the CnC Checkin alert:

(Onion AI response continued):

Finally, we ask Onion AI to investigate another high severity alert for a RAT SSL Cert:

(Onion AI response continued):

Additional analysis is left as an exercise to the reader!

Friday, October 24, 2025

Security Onion 2.4.190 now available including Onion AI Assistant for Pro Customers!

Security Onion 2.4.190 is now available and includes several new features, updated components, and many quality of life improvements!

For Security Onion Pro customers, we've improved our hypervisor feature and added the new Onion AI Assistant!

Updated Components

This release updates several components including:

ATT&CK Navigator
ElastAlert
Elastic Stack
Golang
Nginx
Redis
Telegraf
Zeek

The Elastic and Redis updates resolve security issues so we highly recommend upgrading.

Security Onion Pro Feature: Hypervisor

In the recent 2.4.170 release, we added a new hypervisor feature for Security Onion Pro customers and then improved it in 2.4.180. This release continues to iterate on the Hypervisor feature making it even more powerful! For more information about the Hypervisor feature, please see:

https://docs.securityonion.net/en/2.4/hypervisor.html

Security Onion Pro Feature: Onion AI Assistant

Onion AI is a huge leap forward in leveraging AI to assist you in triaging alerts and working incidents!

https://docs.securityonion.net/en/2.4/assistant.html

Release Notes

There are many more features and fixes included in this release! For a complete list of all changes, please see the Release Notes:

https://docs.securityonion.net/en/2.4/release-notes.html#changes

Known Issues

For a list of known issues, please see:

https://docs.securityonion.net/en/2.4/release-notes.html#known-issues

About Security Onion

Security Onion is a free and open platform built by defenders for defenders. It includes network visibility, host visibility, intrusion detection honeypots, log management, and case management.

Documentation

You can find our online documentation here:

https://docs.securityonion.net/en/2.4/

Documentation is always a work in progress. If you find documentation that needs to be updated, please let us know as described in the Feedback section below.

New Installations

If this is your first time installing Security Onion 2.4, then we highly recommend starting with an IMPORT installation as shown at:

https://docs.securityonion.net/en/2.4/first-time-users.html

Once you’re comfortable with your IMPORT installation, then you can move on to more advanced installations as shown at:

https://docs.securityonion.net/en/2.4/architecture.html

Existing 2.4 Installations

If you have an existing Security Onion 2.4 installation, you can update to the latest version using soup:

https://docs.securityonion.net/en/2.4/soup.html

2.3 EOL

As a reminder, Security Onion 2.3 reached End Of Life (EOL) on April 6, 2024:

https://blog.securityonion.net/2023/10/6-month-eol-notice-for-security-onion-23.html

Thanks

Lots of love went into this release!

Special thanks to all our folks working so hard to make this release happen!

Josh Brower
Jason Ertel
Corey Ogburn
Josh Patterson
Mike Reeves
Jorge Reyes
Matthew Wright

Questions, Problems, and Feedback

If you have any questions or problems, please create a new Discussion at:

https://securityonion.net/discuss

Security Onion Pro

We recently celebrated 10 years in business by announcing Security Onion Pro:

https://blog.securityonion.net/2024/07/celebrating-10-years-of-security-onion.html

Security Onion Pro includes many enterprise features that folks have been asking for:

Active Query Management
External API
Open ID Connect (OIDC)
Data at Rest Encryption
FIPS for the OS
DoD STIG for the OS
External Notifications in SOC
Time Tracking inside of Cases
Guaranteed Message Delivery
Manager of Managers
MCP Server
Security Onion App for Splunk
Hypervisor
Reports
Onion AI Assistant

You can read more about these enterprise features at:

https://securityonion.com/pro

Training

Need training? Start with our free Security Onion Essentials training and then take a look at some of our other official Security Onion training!

https://securityonion.net/training

Security Onion Solutions Hardware Appliances

https://securityonion.com/hardware

Cloud Installations

For new Security Onion 2 installations in the cloud, this new version will soon be available on the AWS, Azure, and GCP marketplaces!

AWS Marketplace and Documentation:

https://securityonion.net/aws/?ref=_ptnr_soc_blog_250917

https://docs.securityonion.net/en/2.4/cloud-amazon.html

Azure Marketplace and documentation:

https://securityonion.net/azure

https://docs.securityonion.net/en/2.4/cloud-azure.html

GCP Marketplace and documentation:

https://securityonion.net/google

https://docs.securityonion.net/en/2.4/cloud-google.html

Thursday, September 25, 2025

Early Bird Discount for upcoming Security Onion Fundamentals Class

Our popular "Security Onion Fundamentals" class will be running Tuesday February 24 through Friday February 27, 2026 in San Antonio TX. Use the following code before November 30, 2025 to get 10% off!

earlybird

For more info and to register, please visit https://securityonionfeb2026.eventbrite.com.

For a list of our upcoming public classes, please visit https://securityonionsolutions.com/training/#public-training.

Tuesday, September 23, 2025

Security Onion Documentation printed book now updated for Security Onion 2.4.180!

We've been offering our Security Onion documentation in book form on Amazon for a few years and it's now been updated for the recently released Security Onion 2.4.180!

Thanks to Richard Bejtlich for writing the inspiring foreword!

Proceeds go to the Rural Technology Fund!

This edition has been updated for Security Onion 2.4.180 and includes a 20% discount code for our on-demand training and certification!

This book covers the following Security Onion topics:

First Time Users
Getting Started
Security Onion Console (SOC)
Security Onion Desktop
Network Visibility
Additional Network Visibility
Host Visibility
Third Party Integrations
Rules
Logs
Updating
Accounts
Services
Customizing for Your Environment
Tricks and Tips
Utilities
Help

Q&A

What is the difference between this book and the online documentation?

Who should get this book?

What is the difference between this edition and the previous edition?

This edition has been updated for Security Onion 2.4.180!

Where do we get it?

https://securityonion.com/book

Wednesday, September 17, 2025

Security Onion 2.4.180 now available including new features, updated components, and quality of life improvements!

Security Onion 2.4.180 is now available and includes several new features, updated components, and many quality of life improvements! For Security Onion Pro customers, we've improved our hypervisor feature from our last release and also added a highly requested reporting feature!

Alert on Offline Agents

Security Onion can now alert on offline agents:

https://docs.securityonion.net/en/2.4/elastic-fleet.html#monitoring-agents

Cancel Your Own Long Running SOC Query

If you run a query in Security Onion Console (Alerts, Dashboards, Hunt) that takes a long time, you now have the ability to cancel your own query by clicking the X on the spinner animation.

Enable Static Hostname Mapping without Reverse DNS Lookups

You can now enable static hostname mappings without having to enable reverse DNS lookups:

https://docs.securityonion.net/en/2.4/soc-customization.html#local-lookups

Please note that if you had previously enabled reverse DNS lookups and want to continue using reverse DNS lookups, then you will need to re-enable it as it has moved to a different config location:

https://docs.securityonion.net/en/2.4/soc-customization.html#reverse-dns

Updated Components

This release updates several components including:

The Elastic and Suricata updates resolve security issues so we highly recommend upgrading.

Security Onion Pro Feature: Manager Hypervisor

In the recent 2.4.170 release, we added a new hypervisor feature for Security Onion Pro customers. This release improves on that by allowing you to run the hypervisor on a manager. For more information about the Hypervisor feature, please see:

https://docs.securityonion.net/en/2.4/hypervisor.html

Security Onion Pro Feature: Reporting

Many customers have requested reporting and we are excited to include it in this release! This includes producing reports and data exports for analytical purposes. This allows you to present relevant data to your broader team:

https://docs.securityonion.net/en/2.4/reports.html

Release Notes

There are many more features and fixes included in this release! For a complete list of all changes, please see the Release Notes:

https://docs.securityonion.net/en/2.4/release-notes.html#changes

Known Issues

For a list of known issues, please see:

https://docs.securityonion.net/en/2.4/release-notes.html#known-issues

About Security Onion

Security Onion is a free and open platform built by defenders for defenders. It includes network visibility, host visibility, intrusion detection honeypots, log management, and case management.

Documentation

You can find our online documentation here:

https://docs.securityonion.net/en/2.4/

Documentation is always a work in progress. If you find documentation that needs to be updated, please let us know as described in the Feedback section below.

New Installations

If this is your first time installing Security Onion 2.4, then we highly recommend starting with an IMPORT installation as shown at:

https://docs.securityonion.net/en/2.4/first-time-users.html

Once you’re comfortable with your IMPORT installation, then you can move on to more advanced installations as shown at:

https://docs.securityonion.net/en/2.4/architecture.html

Existing 2.4 Installations

If you have an existing Security Onion 2.4 installation, you can update to the latest version using soup:

https://docs.securityonion.net/en/2.4/soup.html

2.3 EOL

As a reminder, Security Onion 2.3 reached End Of Life (EOL) on April 6, 2024:

https://blog.securityonion.net/2023/10/6-month-eol-notice-for-security-onion-23.html

Thanks

Lots of love went into this release!

Special thanks to all our folks working so hard to make this release happen!

Josh Brower
Jason Ertel
Corey Ogburn
Josh Patterson
Mike Reeves
Jorge Reyes
Matthew Wright

Questions, Problems, and Feedback

If you have any questions or problems, please create a new Discussion at:

https://securityonion.net/discuss

Security Onion Pro

We recently celebrated 10 years in business by announcing Security Onion Pro:

https://blog.securityonion.net/2024/07/celebrating-10-years-of-security-onion.html

Security Onion Pro includes many enterprise features that folks have been asking for:

Active Query Management
External API
Open ID Connect (OIDC)
Data at Rest Encryption
FIPS for the OS
DoD STIG for the OS
External Notifications in SOC
Time Tracking inside of Cases
Guaranteed Message Delivery
Manager of Managers
MCP Server
Security Onion App for Splunk
Hypervisor
Reports

You can read more about these enterprise features at:

https://securityonion.com/pro

Training

Need training? Start with our free Security Onion Essentials training and then take a look at some of our other official Security Onion training!

https://securityonion.net/training

Security Onion Solutions Hardware Appliances

https://securityonion.com/hardware

Cloud Installations

For new Security Onion 2 installations in the cloud, this new version will soon be available on the AWS, Azure, and GCP marketplaces!

AWS Marketplace and Documentation:

https://securityonion.net/aws/?ref=_ptnr_soc_blog_250917

https://docs.securityonion.net/en/2.4/cloud-amazon.html

Azure Marketplace and documentation:

https://securityonion.net/azure

https://docs.securityonion.net/en/2.4/cloud-azure.html

GCP Marketplace and documentation:

https://securityonion.net/google

https://docs.securityonion.net/en/2.4/cloud-google.html

Monday, August 25, 2025

Quick Malware Analysis: NETSUPPORT RAT pcap from 2025-08-20

Thanks to Brad Duncan for sharing this pcap from 2025-08-20 on his malware traffic analysis site! Due to issues with Google flagging a warning for the site, we're not including the actual hyperlink but it should be easy to find.

We did a quick analysis of this pcap using Security Onion 2.4.170:

https://blog.securityonion.net/2025/08/security-onion-24170-now-available.html

If you'd like to follow along, you can do the following:

install Security Onion 2.4.170 in a VM:
https://docs.securityonion.net/en/2.4/first-time-users.html
import the pcap using the SOC Grid interface:
https://docs.securityonion.net/en/2.4/grid.html#icons-in-lower-left-corner
optionally enable the DNS lookups feature:
https://docs.securityonion.net/en/2.4/soc-customization.html?#reverse-dns-lookups

Want more practice? Check out our other Quick Malware Analysis posts at:

https://blog.securityonion.net/search/label/quick%20malware%20analysis

About Security Onion

Screenshots

Let's start with an overview of all logs generated by Security Onion:

Next, let's focus on just the alerts:

Let's start at the top of the list and work our way down. The first alert is "ET REMOTE_ACCESS NetSupport Remote Admin Checkin". We first review the AI Summary on the right and then we go through the Guided Analysis: