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OSINT

Introduction

Open Source Intelligence (OSINT) is about gathering data from publicly available sources, websites, images, maps, and social media, to uncover hidden information.

In CTF challenges, OSINT tasks may include:

  • Identifying a location from a photo
  • Tracing a username across platforms
  • Searching for password leaks
  • Recovering deleted web content through archives

This section summarizes the most practical OSINT resources and techniques used in CTF and cybersecurity investigations.

General Tools

Tool Purpose
OSINT Framework Find free OSINT resources.
IntelTechniques Public collection of OSINT tools.

Geolocation

Goal: Identify a location based on visual or textual clues.

Common data points to analyze:

  • Architecture, terrain, and language on signs.
  • Vehicle types and license plates.
  • Shadow direction and sun position.
  • Road markings and natural landmarks (mountains, coastlines).

Tools:

Tool Purpose
GeoTips Comprehensive training guide for geolocation challenges (especially Google Street View).
Google Earth / Maps Examine landscapes, buildings, and coordinates.
SunCalc Estimate sun position and shadow direction for time-of-day deductions.
Mapillary Street-level imagery alternative to Google Street View.
What3Words Coordinate locator dividing the world into unique 3‑word addresses.

Approach:

  1. Identify language or signage: note writing systems, road markings, and symbols.
  2. Analyze environmental features: terrain, flora, weather, and vehicles.
  3. Verify coordinates: use map matching on Google Earth or Street View.
  4. Confirm accuracy: align shadows using SunCalc or landmark geometry.

Images

Goal: Investigate and trace images to their origin or related content.

Reverse image searches are often used to find where a photo first appeared, identify people, or locate objects and symbols.

Tools:

Tool Purpose
Google Images Standard reverse image search from URLs or uploads.
Yandex Images Often more effective for faces, buildings, or non‑Western content.
TinEye Reverse image search focused on image matching rather than content.
exiftool Extract embedded metadata such as GPS coordinates, timestamps, and camera info.

Before uploading, always check the image locally with exiftool or strings image.jpg, flags and coordinates are often left in metadata.

For faces or unique landmarks, try both Google and Yandex, each indexes different datasets.

Passwords

Goal: Identify re‑used or compromised passwords, usernames, and email addresses in public leaks.

These tools provide access to leaked credentials (for ethical research use only).

Tool Purpose
dehashed Search database leaks by email, username, or password hash.
LeakCheck Search and API-based credential checking service.
SnusBase Large-scale breach search with hash lookups.
HaveIBeenPwned Free public API to check if an email appears in known breaches.

Tips:

  • Search usernames or emails found in metadata, social media, or archives.
  • Use partial hashes or common passwords in combination with CTF clues.

Web & Social Media

Goal: Uncover deleted or hidden information from websites and public data sources.

Common tasks:

  • Recover deleted web pages or past site states.
  • Search usernames or domains across platforms.

Tools:

Tool Purpose
Wayback Machine View historical versions of websites.
Hunter.io Discover email patterns and addresses linked to domains.
Social Searcher Search multiple social platforms for usernames and keywords.
Shodan Search for exposed machines on the internet.
Sherlock Command-line username search across hundreds of websites.
Maigret OSINT tool for aggregating social accounts tied to a single identity.