PATCH//NOTES Open the interactive version
← All lessons
Foundations · Beginner · 4 min

OSINT

Finding out a lot from what's already public.

What it is

Open-Source Intelligence means gathering information from public sources: websites, social media, job ads, DNS records, code repositories, breach dumps and photo metadata. Attackers use it to plan phishing and find exposed systems. Defenders use it to see their organisation the way attackers do. Ethical OSINT stays on public information and respects privacy: you investigate organisations and threats, not stalk individuals.

Real case · Everyday

Job ads as recon

A job posting asking for 'experience with Fortinet VPN and Citrix' tells an attacker exactly which products to look up vulnerabilities for.

How defenders stop it

  • Audit what your organisation exposes publicly
  • Strip metadata from published files and photos
  • Train staff on oversharing
  • Monitor for leaked credentials and code

Try it yourself

Explore the OSINT Framework

Check yourself

1. Which of these is ethical OSINT practice?

  1. Logging in to someone's account with a guessed password
  2. Reviewing your company's public DNS records and job ads
  3. Buying a stolen database
  4. Tracking a stranger's location
Show answer

Reviewing your company's public DNS records and job ads. OSINT uses public information only and has a legitimate purpose.

2. How do defenders use OSINT?

  1. To buy breached data
  2. To track employees at home
  3. To see their organisation the way attackers do
  4. To break into competitors
Show answer

To see their organisation the way attackers do. Looking at what's publicly exposed shows defenders what an attacker would find first.

3. A photo you publish contains GPS metadata. What's the risk, and the fix?

  1. It's illegal; delete your account
  2. There's no risk
  3. It can reveal where it was taken; strip metadata before publishing
  4. It slows your website; compress it
Show answer

It can reveal where it was taken; strip metadata before publishing. Photo metadata can include location and device details. Strip it from files and photos before they go public.

Answer them in the app to earn XP.

Next: The CIA triad →