STORY DRIVEN OSINT CTF

easy
medium
hard
insane

Gas Attack

Briefing

Greetings, Special Agent.

We have an urgent and very grim scenario on our hands. About 20 minutes ago, we received word from one of our red teams, that they’ve uncovered plans on the dark-web to test a new neuro-toxic gas on an undisclosed city.

The group’s name has not yet been uncovered, but is believed to operate decentralized online, sharing the same ideal in the radical right spheres. Over the past months, we’ve observed talks and discussions, glorification of and finally concrete plans to build a dirty bomb.

As of today, our HUMINT team was able to infiltrate partial circles of the group. Our Red Team was able to pull images from the browser cache of the member our HUMINT team was in contact with.

The image reveals a city, which is believed to be the testing ground for the dirty bomb. We still do not have a time-frame for the attack, all we know is that the amount of gas will cost hundreds of people their lives. Not to mention the suffering ending caused by the gas itself.

Our priorities are to find out more about the group, this is done in collaboration with EUROPOL, hence our main task is finding the location of the city. We hope the realization that the location of their plans has leaked, will cause some of the members to make a bad move.

Your task is to locate the city in the image below.

As always, Special Agent, the contract is yours, if you choose to accept.

Materials

Answer Instruction

Use the answer to unlock the flagfile, this will reward you with your badge.

Construct the answer using the following format in lowercase:

country-city

Flagfile

Be advised, the flagfile is an encrypted ZIP. Make sure your OS supports the ZIP format. Ensure the password contains no hidden characters or formatting, paste in Notepad first if the password doesn’t seem to work.

Download Flagfile here

PS: Don’t forget to claim your Coins and XP, by posting your card in the #card-brag channel in Discord.

Official Write-up

Provided here is the official write-up, it does contain the answer. Use this if you’re stuck, or want to verify if you got the answer correct.

Gas Attack

The challenge involves identifying a city from a satellite image that has been shared on the dark web by a terrorist group planning a chemical attack. The image needs to be analyzed to determine the exact location.

Available Materials

  1. Satellite image of a city
  2. Context about it being a potential target
  3. Information about formatting requirements

Solution Paths

Path 1: Reverse Image Search (Quick Solution)

  1. Save the provided satellite image
  2. Use various RIS tools:
  • Google Images
  • Yandex Images
  • Bing Visual Search
  • TinEye
  1. Results should quickly identify the city

Path 2: Manual Geolocation (Alternative Method)

If RIS fails, look for:

  1. Distinctive architectural features
  2. Road layout patterns
  3. Major landmarks
  4. Urban planning style
  5. Water features or green spaces

Answer Format

Must follow this exact format:

country-city

Example format:

belgium-brussels

Key formatting rules:

  1. All lowercase
  2. Single hyphen between country and city
  3. No spaces
  4. Use English spelling of locations
  5. Remove special characters

Common Pitfalls to Avoid

  1. Wrong case usage
  2. Incorrect spelling of city/country
  3. Missing hyphen
  4. Extra spaces
  5. Using local language names
  6. Wrong format order

Verification Steps

  1. Confirm location matches image
  2. Check country spelling
  3. Verify city spelling
  4. Ensure proper formatting
  5. Compare with example format

Research Tools

  1. Google Images
  2. Yandex Images
  3. TinEye
  4. Bing Visual Search
  5. Google Earth (for verification)

Remember: While RIS is the quickest solution path, it’s good practice to verify the location using other methods to ensure accuracy.

Creator(s): Frank Diepmaat