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Geeking out on Splunk and IT Security

GABRIEL VASSEUR
Geeking out on Splunk & IT Security
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Advent of code in SPL - 2025 day 3
Day 3 is here . Part 1 This one isn't too difficult. Given a series of digits such as 818181911112111, we need to pick two digits (conserving the order) to make the highest 2-digit number possible, so in this example 92. The first digit is obviously the most important, so we always want the highest one available, but we need to reserve at least one digit at the end of the bank for the second digit. So take the bank, remove the last digit, and find the highest digit: Now f


Shrink your windows event logs license costs with ingest actions!
Windows events are a large part of the volume of logs ingested in a lot of splunk deployments. Wouldn't be cool if we could shrink them so they don't eat up so much precious precious license? In this post I'll walk through how I rebuilt Windows Event Logs (WELs) into a compact, Splunk-friendly format, cuting size by up to 60% without breaking field extractions. Key takeaways With a few targeted ingest actions and props/transforms tweaks, you can shrink Windows logs dramatical


ES8 findings, intermediate findings, etc confusion!
The key thing I did not appreciate when I wrote the previous version of this post is that the Risk data model is now fed from...
My SplunkBase Apps


Conf Manager
This is the documentation for the Conf Manager app on splunkbase. This app allows you to search your knowledge objects and track their...


ES-Choreographer
This is the documentation for the ES-Choreographer app on splunkbase. This app offers various frameworks to help manage and improve...


GV-Utils
This is the documentation for the GV-Utils app on splunkbase. This app offers various utilities to solve a number of problems in Splunk:...
Articles


Advent of code in SPL - 2025 day 3
Day 3 is here . Part 1 This one isn't too difficult. Given a series of digits such as 818181911112111, we need to pick two digits (conserving the order) to make the highest 2-digit number possible, so in this example 92. The first digit is obviously the most important, so we always want the highest one available, but we need to reserve at least one digit at the end of the bank for the second digit. So take the bank, remove the last digit, and find the highest digit: Now f


Advent of code in SPL - 2025 day 2
(Edited to use mvrange) Day 2 of the 2025 advent of code challenges is here: https://adventofcode.com/2025/day/2 You won't be able to do it if you haven't done day 1 first . We can break down this challenge in several steps: given a range (e.g. 11-22), enumerate all the IDs within the range (e.g. 11,12,13,...,22) given a number, assess whether it's made of 2 repeated halves somehow do this for all the ranges all together to get the solution Step 1 For this challenge, we'll s


Advent of code in SPL - 2025 day 1
Advent of code is a series of Christmas-themed programming challenges that's been running for more than 10 years now. While SPL is not exactly a fully-fledged programming language, I had heard in the past of at least one person (thank you Paul Dean for the idea!) attempting to do the challenges in SPL and this year I thought I would give it a go. I know it's more than a month too late, but this is the first of a series of articles tackling 2025's challenges in SPL. We won't
Risk Based Alerting


RBA: Aggregate user & system risks!
Since RBA is all about aggregating security events that are related to the same entity, Assets & Identities normalisation is crucial to...


RBA: a better way to dedup risk events
In this post we’re discussing an advanced way to dedup risk events in your risk alerts (RIRs) and at the same time have the RIR results...
TaTalks
Use Ingest Actions to shrink your ingest and make the most of your license!
On the 18th of September 2024 I gave a talk on this topic at the London Splunk User Group meetup. Ingest Actions are a simple feature of...


Maintaining your correlation searches with ES Choreographer
I did a talk at Splunk .conf21 about how to maintain correlation searches: pdf / mp4 . If you’re looking for the source code for the...


Change Tracking in Splunk
Are you tracking changes in your Splunk deployment? Most people don't, unless they can justify having a custom (heavy!) process using...
ABOUT ME
My name is Gabriel.
I'm French.
I'm based in England.
I've got a PhD in theoretical physics.
I've been in the IT security industry since 2006.
I've been working with the Splunk big data platform and their SIEM Enterprise Security since 2016.
I made this website so I could share some of my knowledge.
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