CrowdStrike's system design

0/4
☰
CrowdStrike · system design

CrowdStrike Falcon is one lightweight sensor inside every machine's kernel (the core of the operating system) that decides on the spot, and one cloud that learns from all of them and pushes new rules back several times a day.

+ The whole system in one paragraph

Falcon has two halves. A sensor inside every machine sees every process, file and connection, and blocks attacks on the spot, even offline. A cloud learns from all the sensors and sends new rules back several times a day. On July 19, 2024, one rule file reached every online Windows sensor at once and crashed about 8.5 million machines.

298
of the Fortune 500 protected by CrowdStrike (Apr 30, 2024 — the latest public count we found)[7]
Trillions
cybersecurity events a week correlated in its cloud (fiscal 2026 10-K)[5]
$5.25B
annual recurring revenue (Jan 31, 2026)[5]

In this lesson

4 chapters · ~10 min · a quick check in each

Everything is on this page — just scroll down ↓

Chapter 1 of 4

The whole system

1
Requirements

What it must do — and how well

What Falcon must do (yellow) and how well (blue). The core tension: block from inside the kernel yet never crash the machine, and reach everyone fast yet never all at once.

ⓘ Details & sources

Yellow = what the system must do. Blue = how well it must do it.[2][5]

See every process,file and connectionon the machine.Start in early boot,before malware canrun.Block an attack onthe spot — evenoffline.Learn a new attacktechnique, defendeveryone the sameday.Never crash themachine it protects.Stay light: littleCPU, littlebandwidth.Correlate trillionsof events a week.A bad update neverreaches everyone atonce.
2
Architecture

CrowdStrike Falcon, on one page

All of Falcon on one page. Left: the sensor in every machine sees and blocks on the spot. Right: the cloud correlates every sensor, shows your team, and sends new code and rules back.

ⓘ Details & sources

Left: the sensor on every machine. Right: the cloud that learns from all of them and sends rules back. Drawn as it works since Aug 2024. Click any piece; play a flow.[5][2][1]

Watch it happen:
Each machine — the Falcon sensorCrowdStrike's cloudevery event12new rules5in kernelstream3context3detections4which versionnew codewhen555Apps + usersrun, write, connectDetectionlocal graph + AIKernel driversees all, from bootInterpreterreads channel filesHunters + intelOverWatch, Intel GraphThreat Graphtrillions of events/weekFalcon consoleyour security teamSensor releasescode · N, N-1, N-2Channel filesrules, several a dayValidatorchecks every ruleConfig Systemengineers add rules
clientserviceworkerdatabasequeue dashed border = simplified model
12345
Step 1 of 5

On every machine the kernel driver is told what happens: processes starting, files written, network connections, named pipes.

Quick check

Falcon's cloud correlates trillions of events a week, and a week is about 600,000 seconds. Even 1 trillion a week is roughly…

Pick one — or just keep scrolling, it's not graded.

Keep going — it's free

Create your free account to unlock the rest of CrowdStrike's system design, keep your progress and pick up right where you left off.

  1. 2Detect & respond
  2. 3Shipping updates
  3. 4The 2024 outage
Create my free account →I already have one — log in
Questions & comments

Ask anything about this system, or share how you'd design it.

Log in to join the conversation