CTF OSINT

Quick reference for OSINT CTF challenges. Each technique has a one-liner here; see supporting files for full details.

Additional Resources

social-media.md - Twitter/X (user IDs, Snowflake timestamps, Nitter, memory.lol, Wayback CDX), Tumblr (blog checks, post JSON, avatars), BlueSky search + API, Unicode homoglyph steganography, Discord API, username OSINT (namechk, whatsmyname), platform false positives, multi-platform chains
geolocation-and-media.md - Image analysis, reverse image search, Google Lens cropped region search, reflected/mirrored text reading, geolocation techniques (railroad signs, infrastructure maps, MGRS), EXIF/metadata, hardware identification, newspaper archives, IP geolocation, Google Street View panorama matching, What3Words micro-landmark matching
web-and-dns.md - Google dorking, Google Docs/Sheets enumeration, DNS recon (TXT, zone transfers), Wayback Machine, FEC research, Tor relay lookups, GitHub repository analysis, Telegram bot investigation, WHOIS investigation (reverse WHOIS, historical WHOIS, IP/ASN lookup)

String Identification

40 hex chars -> SHA-1 (Tor fingerprint)
64 hex chars -> SHA-256
32 hex chars -> MD5

Twitter/X Account Tracking

Persistent numeric User ID: https://x.com/i/user/<id> works even after renames.
Snowflake timestamps: (id >> 22) + 1288834974657 = Unix ms.
Wayback CDX, Nitter, memory.lol for historical data. See social-media.md.

Tumblr Investigation

Blog check: curl -sI for x-tumblr-user header. Avatar at /avatar/512. See social-media.md.

Username OSINT

whatsmyname.app (741+ sites), namechk.com. Watch for platform false positives. See social-media.md.

Image Analysis & Reverse Image Search

Google Lens (crop to region of interest), Google Images, TinEye, Yandex (faces). Check corners for visual stego. Twitter strips EXIF. See geolocation-and-media.md.
Cropped region search: Isolate distinctive elements (shop signs, building facades) and search via Google Lens for better results than full-scene search. See geolocation-and-media.md.
Reflected text: Flip mirrored/reflected text (water, glass) horizontally; search partial text with quoted strings. See geolocation-and-media.md.

Geolocation

Railroad signs, infrastructure maps (OpenRailwayMap, OpenInfraMap), process of elimination. See geolocation-and-media.md.
Street View panorama matching: Feature extraction + multi-metric image similarity ranking against candidate panoramas. Useful when challenge image is a crop of a Street View photo. See geolocation-and-media.md.
Road sign OCR: Extract text from directional signs (town names, route numbers) to pinpoint road corridors. Driving side + sign style + script identify the country. See geolocation-and-media.md.
Architecture + brand identification: Post-Soviet concrete = Russia/CIS; named businesses → search locations/branches → cross-reference with coastline/terrain. See geolocation-and-media.md.

MGRS Coordinates

Grid format "4V FH 246 677" -> online converter -> lat/long -> Google Maps. See geolocation-and-media.md.

Metadata Extraction

exiftool image.jpg           # EXIF data
pdfinfo document.pdf         # PDF metadata
mediainfo video.mp4          # Video metadata

Google Dorking

site:example.com filetype:pdf
intitle:"index of" password

See web-and-dns.md.

Google Docs/Sheets

Try /export?format=csv, /pub, /gviz/tq?tqx=out:csv, /htmlview. See web-and-dns.md.

DNS Reconnaissance

dig -t txt subdomain.ctf.domain.com
dig axfr @ns.domain.com domain.com  # Zone transfer

Always check TXT, CNAME, MX for CTF domains. See web-and-dns.md.

Tor Relay Lookups

https://metrics.torproject.org/rs.html#simple/<FINGERPRINT> -- check family, sort by "first seen". See web-and-dns.md.

GitHub Repository Analysis

Check issue comments, PR reviews, commit messages, wiki edits via gh api. See web-and-dns.md.

Telegram Bot Investigation

Find bot references in browser history, interact via /start, answer verification questions. See web-and-dns.md.

FEC Political Donation Research

FEC.gov for committee receipts; 501(c)(4) orgs obscure original funders. See web-and-dns.md.

IP Geolocation

curl "http://ip-api.com/json/103.150.68.150"

See geolocation-and-media.md.

Unicode Homoglyph Steganography

Pattern: Visually-identical Unicode characters from different blocks (Cyrillic, Greek, Math) encode binary data in social media posts. ASCII = 0, homoglyph = 1. Group bits into bytes for flag. See social-media.md.

BlueSky Public API

No auth needed. Endpoints: public.api.bsky.app/xrpc/app.bsky.feed.searchPosts?q=..., app.bsky.actor.searchActors, app.bsky.feed.getAuthorFeed. Check all replies to official posts. See social-media.md.

Resources

Shodan - Internet-connected devices
Censys - Certificate and host search
VirusTotal - File/URL reputation
WHOIS - Domain registration
Wayback Machine - Historical snapshots