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bb-methodology skill

by elementalsouls·elementalsouls/Claude-BugHunter·4.7k stars·MIT

Use at the START of any bug bounty hunting session, when switching targets, or when feeling lost about what to do next. Master orchestrator that combines the 5-phase non-linear hunting workflow with the critical thinking framework (developer psychology, anomaly detection, What-If experiments). Routes to all other skills based on current hunting phase. Also use when asking "what should I do next" or "where am I in the process."

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Install the bb-methodology skill

A skill is a folder. Copy it into your agent's skills folder and the agent loads it when the task matches its description. 

git clone --depth 1 https://github.com/elementalsouls/Claude-BugHunter.git /tmp/Claude-BugHunter
mkdir -p ~/.claude/skills
cp -r /tmp/Claude-BugHunter/skills/bb-methodology ~/.claude/skills/bb-methodology
available in every project

In the Claude apps, zip the folder and upload it from the Skills settings. The folder on GitHub

The instructions your agent would load

SKILL.md as published, without the frontmatter. Read it on GitHub

Bug Bounty Methodology: Workflow + Mindset

Master orchestrator for hunting sessions. Combines the 5-phase non-linear workflow with the critical thinking framework that separates top 1% hunters from the rest.

PART 0: MODE CONFIRMATION (Before Anything Else)

Confirm the engagement type before deciding what counts as a finding. The same target produces a different report shape depending on which mode applies. Getting this wrong is the single biggest waste of time in this workflow — answer it explicitly before Phase 0.

Hard rule: Before Phase 0 runs, write the engagement type as the first line in your hunt notes. If you can't answer it from the user's instruction, ASK once. Don't assume — the mistake costs both you and the triager.

Lesson from an authorized engagement: First-pass on this target produced 5 hygiene findings (SP2013 EoL, permissive CSP, stack traces) shipped in red-team format. The engagement was bug-bounty. Findings would have been N/A'd as "informational, no impact demonstrated." After the corrected pass with hygiene-as-context-not-finding, the same target yielded 11 impact-demonstrated bugs including 3 Critical.

PART 1: MINDSET (How to Think)

Core Principle

Hunting is not "find a bug" -- it is "prove an attack scenario." Think like an attacker with a specific goal, not a scanner looking for patterns.

Daily Discipline: Define, Select, Execute

Before touching any tool:

  1. Define: "Today I target [feature/domain] to achieve [CIA impact]"
  2. Select: Choose 1-2 vuln classes (IDOR, Race Condition, etc.)
  3. Execute: Focus ONLY on selected techniques. No wandering.

5 Ultimate Goals (Pick One Per Session)

  1. Confidentiality -- steal data the attacker shouldn't see
  2. Integrity -- modify data the attacker shouldn't change
  3. Availability -- disrupt service (app-level DoS only)
  4. Account Takeover -- control another user's account
  5. RCE -- execute commands on the server

4 Thinking Domains

1. Critical Thinking (deep analysis)

Question trust boundaries:

  • Frontend control disabled? Send request directly via proxy
  • user_role=user cookie? Change to admin
  • price=1000 in POST? Change to 1
  • blocked? Try

Reverse-engineer developer psychology:

  • Feature A has auth checks -> Similar feature B (newly added) probably doesn't
  • Complex flows (coupon + points + refund) -> Edge cases have bugs
  • /api/v2/user exists -> Does /api/v1/user still work with weaker auth?

What-If experiments:

  • Skip checkout -> hit /checkout/success directly
  • Skip 2FA -> navigate to /dashboard
  • Send coupon request 10x simultaneously -> Race condition?
  • Replace guid=f8a2... with id=100 on sibling endpoint -> IDOR?

2. Multi-Perspective (multiple angles)

3. Tactical Thinking (pattern detection)

  • Naming anomaly: userId everywhere but suddenly user_id -> different dev, weaker security
  • Error diff: Same 403 but different JSON structure -> different backend systems
  • Environment diff: Prod vs Dev/Staging -> debug headers, CSP disabled
  • Version diff: JS file before/after update -> new endpoints, removed params
  • Supply chain: Check framework/library versions for known CVEs
  • Third-party integration: Stripe/Auth0/Intercom -> webhook signature missing?

4. Strategic Thinking (big picture)

  • Asymmetry: Defender must patch ALL holes. You only need ONE.
  • Intuition engineering: Log why something "feels wrong." Verify later. Update mental DB.
  • Unknown management: Can't understand something? Add to "investigate later" list. Just-in-Time Learning.

Amateur vs Pro: 7-Phase Comparison

Two Approach Routes

  • Route A (Feature-based): "This feature is complex" -> deep-dive its input handling -> find vuln
  • Route B (Vuln-based): "I want IDOR" -> find endpoints with sequential IDs -> test access control

Anti-Patterns (Stop Doing These)

  • Program hopping: Stick with one target minimum 2 weeks / 30 hours
  • Tool-only hunting: Automation finds duplicates. Manual testing finds unique bugs.
  • Rabbit hole: Max 45 min per parameter. Set a timer. If stuck, sleep on it.
  • No goal: "Just looking around" = wasted time. Always Define first.

PART 2: WORKFLOW (What to Do)

The 5-Phase Non-Linear Flow

+-------------------------------------------------+
|                                                 |
|  +----------+    +----------+    +----------+   |
|  | 1. RECON |---+| 2. MAP   |---+| 3. FIND  |  |
|  +----------+    +-----+----+    +-----+-----+  |
|       ^                |               |         |
|       |                v               v         |
|       |          +----------+    +----------+    |
|       +----------| 4. PROVE |---+| 5. REPORT|   |
|                  +----------+    +----------+    |
|                                                  |
|  Non-linear: stuck at any phase -> go back       |
|  New API found at phase 3 -> return to phase 2   |
|  WAF blocks at phase 4 -> origin IP from phase 1 |
+-------------------------------------------------+

THIS IS NOT LINEAR. Move freely between phases. When stuck, return to a previous phase.

Phase 0: SESSION START (Every Time)

Before touching any tool, answer these:

  1. Define: "Today I target [feature/domain] to achieve [C/I/A/ATO/RCE]"
  2. Select: Choose 1-2 vuln classes (IDOR, XSS, SSRF, etc.)
  3. Execute: Focus ONLY on selected techniques

Route selection -- Wide or Deep?

Phase 1: RECON

Goal: Maximize attack surface. Find what others missed.

Wide approach (initial sweep):

Subdomain enum -> DNS resolution -> HTTP probing -> Port scan -> Tech detect

Deep approach (targeted):

Google Dorks -> JS file download -> Hidden param discovery -> API mapping

Command: /recon target.com

Phase 2: MAPPING & ANALYSIS

Goal: Understand the app like its developer does.

Checklist:

  • [ ] Map all endpoints (Burp/Caido sitemap + JS analysis)
  • [ ] Identify auth model (cookie, JWT, OAuth, SAML?)
  • [ ] Find business-critical flows (payment, registration, password reset, data export)
  • [ ] Download and analyze JS files for hidden routes, secrets, logic
  • [ ] Identify roles and permissions (user, admin, API keys)
  • [ ] Note "weird" behaviors (anomalies in naming, errors, timing)

Phase 3: VULNERABILITY DISCOVERY

Goal: Find the bug. Use Error-based first, then Blind-based.

Decision flow based on what you're testing:

What input are you testing?
+-- ID parameter (user_id, order_id)
|   -> IDOR checklist
+-- Search/filter/sort field
|   -> SQLi, NoSQLi probing
+-- URL input / webhook / PDF gen
|   -> SSRF checklist
+-- Text field reflected in page
|   -> XSS (DOM or reflected)
+-- File upload
|   -> SVG XSS, web shell, path traversal
+-- Price/quantity/coupon
|   -> Business logic, race conditions
+-- Login / 2FA / password reset
|   -> Auth bypass
+-- Profile update API
|   -> Mass Assignment
+-- Template / wiki editor
|   -> SSTI
+-- Nothing obvious
    -> Fuzz with ffuf, try Error-based probing

Error vs Blind decision:

  1. Try Error-based first (send ', ", {{77}}, ${77}) -- watch for 500 errors, stack traces
  2. No error? Time-based (SLEEP(10), ; sleep 10;) -- watch response time
  3. No time diff? OOB (curl attacker.com, interactsh) -- watch for DNS callback
  4. Still nothing? Boolean (AND 1=1 vs AND 1=0) -- watch content-length diff

Phase 4: PROVE & ESCALATE

Goal: Prove maximum business impact. Turn Low into Critical.

Escalation decision:

More skills from elementalsouls/Claude-BugHunter

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