Caido Mode Skill

Overview

Full-coverage CLI for Caido's API, built on the official @caido/sdk-client package. Covers:

• HTTP History - Search, retrieve, replay, edit requests with HTTPQL
• Replay & Sessions - Sessions, collections, entries, fuzzing
• Scopes - Create and manage testing scopes (allowlist/denylist patterns)
• Filter Presets - Save and reuse HTTPQL filter presets
• Environments - Store test variables (victim IDs, tokens, etc.)
• Findings - Create, list, update security findings
• Tasks - Monitor and cancel background tasks
• Projects - Switch between testing projects
• Hosted Files - Manage files served by Caido
• Intercept - Enable/disable request interception programmatically
• Plugins - List installed plugins
• Export - Convert requests to curl commands for PoCs
• Health - Check Caido instance status

All traffic goes through Caido, so it appears in the UI for further analysis.

Why This Model?

Cookies and auth tokens can be huge - session cookies, JWTs, CSRF tokens can easily be 1-2KB. Rather than manually copy-pasting:

1. Find an organic request in Caido's HTTP history that already has valid auth
2. Use edit to modify just what you need (path, method, body) while keeping all auth headers intact
3. Send it - response comes back with full context preserved

Authentication Setup

Setup (One-Time)

1. Open Dashboard → Developer → Personal Access Tokens
2. Create a new token
3. Run:

npx tsx ~/.claude/skills/caido-mode/caido-client.ts setup <your-pat>

# Non-default Caido instance
npx tsx ~/.claude/skills/caido-mode/caido-client.ts setup <pat> http://192.168.1.100:8080

# Or set env var instead
export CAIDO_PAT=caido_xxxxx

The setup command validates the PAT via the SDK (which exchanges it for an access token), then saves both the PAT and the cached access token to ~/.claude/config/secrets.json. Subsequent runs load the cached token directly, skipping the PAT exchange.

Check Status

npx tsx ~/.claude/skills/caido-mode/caido-client.ts auth-status

How Auth Works

The SDK uses a device code flow internally — the PAT auto-approves it and receives an access token + refresh token. A custom SecretsTokenCache (implementing the SDK's TokenCache interface) persists these tokens to secrets.json so they survive across CLI invocations.

Auth resolution: CAIDO_PAT env var → secrets.json PAT → error with setup instructions

CLI Tool

Located at ~/.claude/skills/caido-mode/caido-client.ts. All commands output JSON.

HTTP History & Testing Commands

search - Search HTTP history with HTTPQL

npx tsx caido-client.ts search 'req.method.eq:"POST" AND resp.code.eq:200'
npx tsx caido-client.ts search 'req.host.cont:"api"' --limit 50
npx tsx caido-client.ts search 'req.path.cont:"/admin"' --ids-only
npx tsx caido-client.ts search 'resp.raw.cont:"password"' --after <cursor>

recent - Get recent requests

npx tsx caido-client.ts recent
npx tsx caido-client.ts recent --limit 50

get / get-response - Retrieve full details

npx tsx caido-client.ts get <request-id>
npx tsx caido-client.ts get <request-id> --headers-only
npx tsx caido-client.ts get-response <request-id>
npx tsx caido-client.ts get-response <request-id> --compact

edit - Edit and replay (KEY FEATURE)

Modifies an existing request while preserving all cookies/auth headers:

# Change path (IDOR testing)
npx tsx caido-client.ts edit <id> --path /api/user/999

# Change method and add body
npx tsx caido-client.ts edit <id> --method POST --body '{"admin":true}'

# Add/remove headers
npx tsx caido-client.ts edit <id> --set-header "X-Forwarded-For: 127.0.0.1"
npx tsx caido-client.ts edit <id> --remove-header "X-CSRF-Token"

# Find/replace text anywhere in request
npx tsx caido-client.ts edit <id> --replace "user123:::user456"

# Combine multiple edits
npx tsx caido-client.ts edit <id> --method PUT --path /api/admin --body '{"role":"admin"}' --compact

replay / send-raw - Send requests

# Replay as-is
npx tsx caido-client.ts replay <request-id>

# Replay with custom raw
npx tsx caido-client.ts replay <id> --raw "GET /modified HTTP/1.1\r\nHost: example.com\r\n\r\n"

# Send completely custom request
npx tsx caido-client.ts send-raw --host example.com --port 443 --tls --raw "GET / HTTP/1.1\r\nHost: example.com\r\n\r\n"

export-curl - Convert to curl for PoCs

npx tsx caido-client.ts export-curl <request-id>

Outputs a ready-to-use curl command with all headers and body.

Replay Sessions & Collections

Sessions

# Create replay session from an existing request
npx tsx caido-client.ts create-session <request-id>

# ALWAYS rename sessions for easy identification in Caido UI
npx tsx caido-client.ts rename-session <session-id> "idor-user-profile"

# List all replay sessions
npx tsx caido-client.ts replay-sessions
npx tsx caido-client.ts replay-sessions --limit 50

# Delete replay sessions
npx tsx caido-client.ts delete-sessions <session-id-1>,<session-id-2>

Collections

Organize replay sessions into collections:

# List replay collections
npx tsx caido-client.ts replay-collections
npx tsx caido-client.ts replay-collections --limit 50

# Create a collection
npx tsx caido-client.ts create-collection "IDOR Testing"

# Rename a collection
npx tsx caido-client.ts rename-collection <collection-id> "Auth Bypass Tests"

# Delete a collection
npx tsx caido-client.ts delete-collection <collection-id>

Fuzzing

# Create automate session for fuzzing
npx tsx caido-client.ts create-automate-session <request-id>

# Start fuzzing (configure payloads and markers in Caido UI first)
npx tsx caido-client.ts fuzz <session-id>

Scope Management

Define what's in scope for your testing. Uses glob patterns.

# List all scopes
npx tsx caido-client.ts scopes

# Create scope with allowlist and denylist
npx tsx caido-client.ts create-scope "Target Corp" --allow "*.target.com,*.target.io" --deny "*.cdn.target.com"

# Update scope
npx tsx caido-client.ts update-scope <scope-id> --allow "*.target.com,*.api.target.com"

# Delete scope
npx tsx caido-client.ts delete-scope <scope-id>

Glob patterns: *.example.com matches any subdomain of example.com.

Filter Presets

Save frequently used HTTPQL queries as named presets.

# List saved filters
npx tsx caido-client.ts filters

# Create filter preset
npx tsx caido-client.ts create-filter "API Errors" --query 'req.path.cont:"/api/" AND resp.code.gte:400'
npx tsx caido-client.ts create-filter "Auth Endpoints" --query 'req.path.regex:"/(login|auth|oauth)/"' --alias "auth"

# Update filter
npx tsx caido-client.ts update-filter <filter-id> --query 'req.path.cont:"/api/" AND resp.code.gte:500'

# Delete filter
npx tsx caido-client.ts delete-filter <filter-id>

Environment Variables

Store testing variables that persist across sessions. Great for IDOR testing with multiple user IDs.

# List environments
npx tsx caido-client.ts envs

# Create environment
npx tsx caido-client.ts create-env "IDOR-Test"

# Set variables
npx tsx caido-client.ts env-set <env-id> victim_user_id "user_456"
npx tsx caido-client.ts env-set <env-id> attacker_token "eyJhbG..."

# Select active environment
npx tsx caido-client.ts select-env <env-id>

# Deselect environment
npx tsx caido-client.ts select-env

# Delete environment
npx tsx caido-client.ts delete-env <env-id>

Findings

Create, list, and update security findings. Shows up in Caido's Findings tab.

# List all findings
npx tsx caido-client.ts findings
npx tsx caido-client.ts findings --limit 50

# Get a specific finding
npx tsx caido-client.ts get-finding <finding-id>

# Create finding linked to a request
npx tsx caido-client.ts create-finding <request-id> \
  --title "IDOR in user profile endpoint" \
  --description "Can access other users' profiles by changing ID parameter" \
  --reporter "rez0"

# With deduplication key (prevents duplicates)
npx tsx caido-client.ts create-finding <request-id> \
  --title "Auth bypass on /admin" \
  --dedupe-key "admin-auth-bypass"

# Update finding
npx tsx caido-client.ts update-finding <finding-id> \
  --title "Updated title" \
  --description "Updated description"

Tasks

Monitor and cancel background tasks (imports, exports, etc.).

# List all tasks
npx tsx caido-client.ts tasks

# Cancel a running task
npx tsx caido-client.ts cancel-task <task-id>

Project Management

# List all projects
npx tsx caido-client.ts projects

# Switch active project
npx tsx caido-client.ts select-project <project-id>

Hosted Files

# List hosted files
npx tsx caido-client.ts hosted-files

# Delete hosted file
npx tsx caido-client.ts delete-hosted-file <file-id>

Intercept Control

# Check intercept status
npx tsx caido-client.ts intercept-status

# Enable/disable interception
npx tsx caido-client.ts intercept-enable
npx tsx caido-client.ts intercept-disable

Info, Health & Plugins

# Current user info
npx tsx caido-client.ts viewer

# List installed plugins
npx tsx caido-client.ts plugins

# Check Caido instance health (version, ready state)
npx tsx caido-client.ts health

Output Control

Works with get, get-response, replay, edit, send-raw:

HTTPQL Reference

Caido's query language for searching HTTP history.

CRITICAL: String values MUST be quoted. Integer values are NOT quoted.

CRITICAL: HTTPQL has NO NOT operator. Never write NOT expr. Use the negated operator variant instead:

• ncont (not contains), nlike (not like), nregex (not regex), ne (not equals)
• Wrong: NOT req.path.cont:"/admin"
• Right: req.path.ncont:"/admin"

Namespaces and Fields

Operators

String: eq, ne, cont, ncont, like, nlike, regex, nregex Integer: eq, ne, gt, gte, lt, lte Boolean: eq, ne Logical: AND, OR, parentheses for grouping

Example Queries

# POST requests with 200 responses
req.method.eq:"POST" AND resp.code.eq:200

# API requests
req.host.cont:"api" OR req.path.cont:"/api/"

# Standalone string searches both req and resp
"password" OR "secret" OR "api_key"

# Error responses
resp.code.gte:400 AND resp.code.lt:500

# Large responses (potential data exposure)
resp.len.gt:100000

# Slow endpoints
resp.roundtrip.gt:5000

# Auth endpoints by regex
req.path.regex:"/(login|auth|signin|oauth)/"

# Replay/automate traffic only
source:"replay" OR source:"automate"

# Date filtering
req.created_at.gt:"2024-01-01T00:00:00Z"

# Exclude paths (use ncont, NOT doesn't exist)
req.path.ncont:"/static"

# Not equal
req.method.ne:"OPTIONS"

# Combine negations
req.path.ncont:"/health" AND req.path.ncont:"/metrics"

SDK Architecture

This CLI is built on @caido/sdk-client v0.1.4+, using a clean multi-file architecture:

caido-client.ts          # CLI entry point — arg parsing + command dispatch
lib/
  client.ts              # SDK Client singleton, SecretsTokenCache, auth config
  graphql.ts             # gql documents for features not yet in SDK
  output.ts              # Output formatting (truncation, headers-only, raw→curl)
  types.ts               # Shared types (OutputOpts)
  commands/
    requests.ts          # search, recent, get, get-response, export-curl
    replay.ts            # replay, send-raw, edit, sessions, collections, automate, fuzz
    findings.ts          # findings, get-finding, create-finding, update-finding
    management.ts        # scopes, filters, environments, projects, hosted-files, tasks
    intercept.ts         # intercept-status, intercept-enable, intercept-disable
    info.ts              # viewer, plugins, health, setup, auth-status

SDK Coverage

Most features use the high-level SDK directly:

Features not yet in the high-level SDK use client.graphql.query()/client.graphql.mutation() with gql tagged templates from graphql-tag. This is the proper SDK approach (typed documents through urql) — no raw fetch anywhere.

Workflow Examples

1. IDOR Testing (Primary Pattern)

# Find authenticated request
npx tsx caido-client.ts search 'req.path.cont:"/api/user"' --limit 10

# Create scope
npx tsx caido-client.ts create-scope "IDOR-Test" --allow "*.target.com"

# Create environment for test data
npx tsx caido-client.ts create-env "IDOR-Test"
npx tsx caido-client.ts env-set <env-id> victim_id "user_999"

# Test IDOR by changing user ID
npx tsx caido-client.ts edit <request-id> --path /api/user/999

# Mark as finding if it works
npx tsx caido-client.ts create-finding <request-id> --title "IDOR on /api/user/:id"

# Export curl for PoC
npx tsx caido-client.ts export-curl <request-id>

2. Privilege Escalation Testing

npx tsx caido-client.ts search 'req.path.cont:"/admin"' --limit 10
npx tsx caido-client.ts edit <id> --path /api/admin/users --method GET
npx tsx caido-client.ts edit <id> --method POST --body '{"role":"admin"}'

3. Header Bypass Testing

npx tsx caido-client.ts edit <id> --set-header "X-Forwarded-For: 127.0.0.1"
npx tsx caido-client.ts edit <id> --set-header "X-Original-URL: /admin"
npx tsx caido-client.ts edit <id> --remove-header "X-CSRF-Token"

4. Fuzzing with Automate

npx tsx caido-client.ts create-automate-session <request-id>
# Configure payload markers and wordlists in Caido UI
npx tsx caido-client.ts fuzz <session-id>

5. Filter + Analyze Pattern

# Save useful filters
npx tsx caido-client.ts create-filter "API 4xx" --query 'req.path.cont:"/api/" AND resp.code.gte:400 AND resp.code.lt:500'
npx tsx caido-client.ts create-filter "Large Responses" --query 'resp.len.gt:100000'
npx tsx caido-client.ts create-filter "Sensitive Data" --query '"password" OR "secret" OR "api_key" OR "token"'

# Quick search using preset alias
npx tsx caido-client.ts search 'preset:"API 4xx"' --limit 20

Instructions for Claude

1. PREFER edit OVER replay --raw - preserves cookies/auth automatically
2. Workflow: Search → find request with valid auth → use that ID for all tests via edit
3. Don't dump raw requests into context - use --compact or --headers-only when exploring
4. Always check auth first: health to verify connection, then recent --limit 1
5. ALWAYS NAME REPLAY TABS: rename-session <id> "idor-user-profile"
6. Create findings for anything interesting - they show up in Caido's Findings tab
7. Use export-curl when building PoCs for reports
8. Create filter presets for recurring searches to save typing
9. Use environments to store test data (victim IDs, tokens, etc.)
10. Output is JSON - parse response fields as needed
11. NEVER use NOT in HTTPQL - it doesn't exist. Use negated operators: ne, ncont, nlike, nregex

Performance & Context Optimization

• search/recent omit raw field (~200 bytes per request, safe for 100+)
• get fetches raw (~5-20KB per request, fetch only what you need)
• Use --limit aggressively (start with 5-10)
• Use --compact flag for quick exploration
• Filter server-side with HTTPQL, not client-side

Error Handling

• Auth errors: Run npx tsx caido-client.ts auth-status to check, re-setup with npx tsx caido-client.ts setup <pat>
• Connection refused: Caido not running → npx tsx caido-client.ts health
• InstanceNotReadyError: Caido is starting up, wait and retry

Related Skills

• caido-plugin-dev - For building Caido plugins (backend + frontend)
• spider - Crawling with Katana (uses Caido as proxy)
• website-fuzzing - Remote ffuf fuzzing on hunt6
• JsAnalyzer - JS analysis for traffic-discovered files