ctf-osint
The ctf-osint skill provides rapid-reference techniques for open source intelligence in capture-the-flag challenges, covering social media analysis, geolocation from images and landmarks, DNS reconnaissance, web archive searching, username enumeration across platforms, EXIF metadata extraction, Google dorking, WHOIS lookups, Tor relay identification, and hash/coordinate recognition. Use this skill when tasked with gathering intelligence from publicly available sources during reconnaissance phases of CTF competitions.
git clone --depth 1 https://github.com/ljagiello/ctf-skills /tmp/ctf-osint && cp -r /tmp/ctf-osint/ctf-osint ~/.claude/skills/ctf-osintSKILL.md
# CTF OSINT Quick reference for OSINT CTF challenges. Each technique has a one-liner here; see supporting files for full details. ## Prerequisites **Python packages (all platforms):** ```bash pip install shodan Pillow ``` **Linux (apt):** ```bash apt install whois dnsutils nmap libimage-exiftool-perl imagemagick curl ``` **macOS (Homebrew):** ```bash brew install whois bind nmap exiftool imagemagick curl ``` ## Additional Resources - [social-media.md](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, Osint Industries), username metadata mining (postal codes), platform false positives, multi-platform chains, Strava fitness route OSINT - [geolocation-and-media.md](geolocation-and-media.md) - Image analysis, reverse image search (including Baidu for China), Google Lens cropped region search, reflected/mirrored text reading, geolocation techniques (railroad signs, infrastructure maps, MGRS), Google Plus Codes, EXIF/metadata, hardware identification, newspaper archives, IP geolocation, Google Street View panorama matching, What3Words micro-landmark matching, Google Maps crowd-sourced photo verification, Overpass Turbo spatial queries, music-themed landmark geolocation with key encoding - [web-and-dns.md](web-and-dns.md) - Google dorking (including TBS image filters), 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), fake service banner detection via nmap fingerprinting --- ## When to Pivot - If you already have the files or packets locally and now need extraction or carving, switch to `/ctf-forensics`. - If the task becomes active exploitation of a live HTTP service, switch to `/ctf-web`. - If you uncover malware samples, beacons, or suspicious binaries during attribution, switch to `/ctf-malware`. ## Quick Start Commands ```bash # DNS recon dig -t any target.com dig -t txt target.com dig axfr @ns.target.com target.com whois target.com # Image metadata exiftool image.jpg identify -verbose image.jpg | head -30 # Web archive curl "https://web.archive.org/web/20230101*/target.com" # Username lookup curl -s "https://whatsmyname.app/api/lookup?username=<user>" # Shodan shodan search "hostname:target.com" shodan host <ip> ``` ## 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](social-media.md). ## Tumblr Investigation - Blog check: `curl -sI` for `x-tumblr-user` header. Avatar at `/avatar/512`. See [social-media.md](social-media.md). ## Username OSINT - [whatsmyname.app](https://whatsmyname.app) (741+ sites), [namechk.com](https://namechk.com). Watch for platform false positives. See [social-media.md](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](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](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-and-media.md). ## Geolocation - Railroad signs, infrastructure maps (OpenRailwayMap, OpenInfraMap), process of elimination. See [geolocation-and-media.md](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](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](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](geolocation-and-media.md). - **Music-themed landmark geolocation:** Multiple images of music-related landmarks worldwide; each yields a piano key number encoding one flag character. Identify all locations first, then decode the key sequence. See [geolocation-and-media.md](geolocation-and-media.md). ## MGRS Coordinates - Grid format "4V FH 246 677" -> online converter -> lat/long -> Google Maps. See [geolocation-and-media.md](geolocation-and-media.md). ## Google Plus Codes - Format `XXXX+XXX` (chars: `23456789CFGHJMPQRVWX`). Drop a pin on Google Maps → Plus Code appears in details. Free, no API key needed. See [geolocation-and-media.md](geolocation-and-media.md). ## Metadata Extraction ```bash exiftool image.jpg # EXIF data pdfinfo document.pdf # PDF metadata mediainfo video.mp4 # Video metadata ``` ## Google Dorking ```text site:example.com filetype:pdf intitle:"index of" password ``` **Image TBS filters:** Append `&tbs=itp:face` to Google Image URLs to filter for faces only (strips logos/banners). See [web-and-dns.md](web-and-dns.md). ## Google Docs/Sheets - Try `/export?format=csv`, `/pub`, `/gviz/tq?tqx=out:csv`, `/htmlview`. See [web-and-dns.md](web-and-dns.md). ## DNS Reconnaissance
Provides AI and machine learning techniques for CTF challenges. Use when attacking ML models, crafting adversarial examples, performing model extraction, prompt injection, membership inference, training data poisoning, fine-tuning manipulation, neural network analysis, LoRA adapter exploitation, LLM jailbreaking, or solving AI-related puzzles.
Provides cryptography attack techniques for CTF challenges. Use when attacking encryption, hashing, signatures, ZKP, PRNG, or mathematical crypto problems involving RSA, AES, ECC, lattices, LWE, CVP, number theory, Coppersmith, Pollard, Wiener, padding oracle, GCM, key derivation, or stream/block cipher weaknesses.
Provides digital forensics and signal analysis techniques for CTF challenges. Use when analyzing disk images, memory dumps, event logs, network captures, cryptocurrency transactions, steganography, PDF analysis, Windows registry, Volatility, PCAP, Docker images, coredumps, side-channel power traces, DTMF audio spectrograms, packet timing analysis, CD audio disc images, or recovering deleted files and credentials.
Provides malware analysis and network traffic techniques for CTF challenges. Use when analyzing obfuscated scripts, malicious packages, custom crypto protocols, C2 traffic, PE/.NET binaries, RC4/AES encrypted communications, YARA rules, shellcode analysis, memory forensics for malware (Volatility malfind, process injection detection), anti-analysis techniques (VM/sandbox detection, timing evasion, API hashing, process injection, environment checks), or extracting malware configurations and indicators of compromise.
Provides miscellaneous CTF challenge techniques for problems that do not cleanly fit the main categories. Use for encoding puzzles, pyjails, bash jails, RF/SDR, DNS oddities, unicode tricks, esoteric languages, QR or audio puzzles, constraint solving, game theory, unusual sandbox escapes, and hybrid logic puzzles. Prefer a more specific skill first when the challenge is mainly web, pwn, reverse, forensics, malware, OSINT, or crypto. Treat this as the fallback skill for genuine cross-category or edge-case challenges, not the default starting point.
Provides binary exploitation techniques for CTF challenges. Use when you already have a vulnerable native target or service and need to turn memory corruption or low-level primitives into code execution or privilege escalation, such as buffer overflows, format strings, heap bugs, ROP, ret2libc, shellcode, kernel exploitation, seccomp bypass, sandbox escape, or Windows/Linux exploit chains. Do not use it when the main blocker is understanding what the binary does; use reverse engineering first. Do not use it for pure web bugs, disk or packet forensics, or standalone crypto/math challenges.
Provides reverse engineering techniques for CTF challenges. Use when the main job is to understand how a compiled, obfuscated, packed, or virtualized target works before exploiting or solving it, including binaries, APKs, WASM, firmware, custom VMs, bytecode, game clients, malware-like loaders, and anti-debug or anti-analysis logic. Do not use it when the vulnerability is already understood and the remaining task is exploitation; use pwn instead. Do not use it for pure web workflows, log or disk forensics, or standalone crypto problems unless reversing the implementation is the real blocker.
Provides web exploitation techniques for CTF challenges. Use when the target is primarily an HTTP application, API, browser client, template engine, identity flow, or smart-contract frontend/backend surface, including XSS, SQLi, SSTI, SSRF, XXE, JWT, auth bypass, file upload, request smuggling, OAuth/OIDC, SAML, prototype pollution, and similar web bugs. Do not use it for native binary memory corruption, reverse engineering of standalone executables, disk or memory forensics, or pure cryptanalysis unless the web flaw is still the main path to the flag.