Security Onion: 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