ctf-similar-search

CTF Similar Challenge Search

Search for similar CTF challenge writeups using Tavily API.

Prerequisites

pip install requests tavily

Set your Tavily API key (from https://tavily.com) before running:

export TAVILY_API_KEY='tvly-...'

API Overview

This skill provides two interfaces:

Interface	Purpose	Command
Tavily Search	Search for writeups and articles	./search.sh search <keyword>
Tavily Extract	Extract content from URLs	./search.sh extract <url1> [url2] ...

Search Workflow

Step 1: Search with Keywords

Choose keywords based on available information:

Scenario 1: Known Competition + Challenge Name

# Format: [Competition Name] [Challenge Name] — max 3 words
./search.sh search "DASCTF URL Storage"
./search.sh search "HGAME baby web"
./search.sh search "BUUCTF pwn1"

Scenario 2: Challenge Name Only (no competition info)

# Use challenge name directly — max 3 words
./search.sh search "URL Storage"
./search.sh search "baby overflow"
./search.sh search "crypto-rsa"

Scenario 3: Unique Identifiers (code snippets, strings)

# Use unique, non-trivial strings from the challenge — NO word limit
./search.sh search "def encrypt_flag(key): return base64"
./search.sh search "CUSTOM_MAGIC_BYTES"
./search.sh search "ERROR: invalid padding in AES block"

⚠️ Critical: 3-Word Limit for Non-Code Queries

All keyword searches that are NOT code snippets or unique identifier strings MUST NOT exceed 3 words. This constraint ensures precise, focused queries that return relevant CTF writeup results instead of broad, diluted searches.

Search Type	Word Limit	Examples
Competition + Challenge name	≤ 3 words	"DASCTF URL Storage", "HGAME baby web"
Challenge name only	≤ 3 words	"URL Storage", "baby overflow"
Code snippets / strings	No limit	"def encrypt_flag(key): return base64"
Error messages / identifiers	No limit	"CUSTOM_MAGIC_BYTES", "ERROR: invalid padding in AES block"

For competition + challenge name searches, drop filler words (year numbers, "CTF", "competition", "writeup", "solution") and keep only the 3 most distinctive words:

• ❌ "HGAME 2024 baby web challenge" (5 words)
• ✅ "HGAME baby web" (3 words)
• ❌ "DASCTF 2023 URL Storage writeup" (5 words)
• ✅ "DASCTF URL Storage" (3 words)
• ❌ "PlaidCTF 2025 zero day exploit solution" (6 words)
• ✅ "PlaidCTF zero day" (3 words)

For code/string searches, use the entire unique snippet — these are exempt from the word limit:

• ✅ "def xor_encrypt(data, key):" (code — exempt)
• ✅ "ERROR: invalid padding in AES block" (error string — exempt)
• ✅ "CUSTOM_MAGIC_BYTES" (identifier — exempt)

Keyword Rules

✅ Good Keywords	❌ Bad Keywords
Competition + Challenge name (≤3 words)	Single vulnerability type (SSRF, XSS)
Challenge name (≤3 words)	Generic terms (web, pwn, crypto)
Unique code snippets (no word limit)	Full sentences
Specific error messages (no word limit)	Articles (a, the, in)
Library/framework names	Generic strings (flag{}, etc.)
Custom function names	Tool names alone

Why avoid these?

• "SSRF" → returns generic vulnerability explanations, not CTF writeups
• "flag{" → returns millions of unrelated results
• "URL Storage DASCTF" → returns specific CTF challenges

Why the 3-word limit?

• Forces precision: only the most distinctive keywords survive
• Filters noise: filler words like "challenge", "writeup", "solution" dilute results
• Improves API efficiency: shorter, focused queries consume fewer credits

Key principle: Use keywords that uniquely identify THIS challenge, not the general technique or common patterns. Keep non-code queries to 3 words or fewer.

Step 2: Review Search Results

The search returns:

• Answer: AI-generated summary if available
• Results: List of URLs with titles and content previews
• Credits: API usage information

Step 3: Extract Content (Optional)

If a search result looks promising, extract its full content:

# Single URL
./search.sh extract "https://example.com/writeup"

# Multiple URLs
./search.sh extract "https://url1.com" "https://url2.com"

Step 4: Analyze and Pivot

Based on extracted content:

• Identify common techniques used in similar challenges
• Determine if the approach is applicable
• Pivot to category-specific skill if needed

When to Pivot

• If the challenge is already well-categorized, use the specific ctf-* skill
• If you need OSINT techniques, use ctf-osint
• If you need to generate a writeup after solving, use ctf-writeup

Quick Start

# Scenario 1: Competition + Challenge name (≤3 words)
./search.sh search "DASCTF URL Storage"

# Scenario 2: Challenge name only (≤3 words)
./search.sh search "URL Storage"

# Scenario 3: Unique identifier from challenge (no word limit)
./search.sh search "def xor_encrypt(data, key):"
./search.sh search "ERROR: invalid padding"

# Extract content from promising results
./search.sh extract "https://ctftime.org/writeup/12345"

Tips

1. Be specific: Use competition name + challenge name when available
2. Use unique strings: Code snippets, error messages, unique identifiers
3. Avoid generic terms: Don't search "SSRF CTF writeup" - too broad
4. Review first: Check search results before extracting
5. Extract selectively: Only extract URLs that look relevant
6. Respect the 3-word limit: For non-code queries, strip filler words and keep only the 3 most distinctive keywords

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