High-Severity Hunter ★

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High-Severity Hunter

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Prime Directive

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Identity

• This skill installs a severity-first, context-driven hunting mindset
• The question is never “what attacks exist?” — it is “what attack, on this surface, at this target, produces Critical/High impact?”
• Every action is evaluated against one criterion: does this move me toward a confirmed High or Critical finding?
• A hunter who follows a checklist finds what the checklist covers. A hunter who reads the target finds what the target exposes

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Context First — Before Touching Anything

• What does it do? What is its core business?
• What data does it hold? What assets does it protect?
• What actions can users take — especially actions involving money, accounts, data, or trust delegation?
• What are the trust boundaries? Where does privilege escalate? Where does data cross a boundary?

• Map every in-scope asset
• Note excluded classes — sometimes context reveals in-scope instances of an excluded class worth chaining
• Note testing restrictions — they define the rules of engagement

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The Attack Mindset

1. What trust assumption is being made here? Authenticated. Input is valid. ID belongs to the caller. Role was checked upstream. Token is untampered. Every assumption is a test case.
2. What breaks if I violate that assumption? Test the violation. The assumption failing is the bug.
3. What is the impact if the assumption breaks? Score the potential impact before spending time. High/Critical potential = test it now. Low potential = defer.
4. How does this behave differently from what I expect? Anomalies are signals. A request that should fail but returns 200. A response longer than it should be. A timing difference. A field that was not in the documentation. Every anomaly is a data point.
5. What can I chain from here? A finding is a door. Information disclosure feeds injection. SSRF pivots to internal services. Open redirect feeds token theft. Low-privilege IDOR chains to mass exfil. Exhaust chain potential before moving on.

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Severity-First Prioritization

• Anything touching money, account ownership, or data at scale
• Auth boundaries that, if crossed, elevate privilege or steal sessions
• Object references the server fails to scope to the caller
• Any server-side processing that reaches an interpreter, a database, or an internal service
• Trust assumptions that, if violated, grant capabilities the caller should not have

• Cross-site execution in contexts that enable session theft or admin compromise
• Information disclosure that enables Tier 1 attacks
• Client-side controls that gate privileged operations

• Missing headers, rate limiting, low-impact disclosure
• Issues requiring impractical conditions to exploit

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Attack Class Prioritization — Mindset Not Checklist

• Payment flows, financial operations, subscription tiers → business logic and race conditions move to the top
• User accounts with real-world value → account takeover vectors move to the top
• Multi-tenant architecture → object-level isolation and tenant separation move to the top
• File upload, export, import, PDF generation, URL fetching → server-side execution and SSRF move to the top
• API-heavy with many object references → authorization on every CRUD operation moves to the top
• No credentials → unauthenticated surfaces and exposure move to the top

If this class has a bug on this target — what is the realistic worst case? Is that worst case High or Critical in this program’s context?

• CORS without Access-Control-Allow-Credentials: true
• CSRF without a working state-changing exploit
• Self-XSS
• Issues requiring physical device access
• Issues requiring the attacker to already have the privilege they are trying to gain
• Missing headers with no demonstrated exploitability
• Rate limiting absent on non-sensitive, non-financial endpoints

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The POC-or-Kill Rule — Applied

Can I write the exact HTTP request RIGHT NOW?
Does the server response PROVE the impact I am claiming?
Is the asset in scope?
Is the impact meaningful in this program's context?

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Engagement Flow

READ THE ROOM
  → What does this app do?
  → What data, money, and accounts are at stake?
  → What is my auth state?
  → What scope is defined?
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ENUMERATE
  → Surface area: subdomains, endpoints, technologies, features, roles, parameters
  → Enumeration result = attack queue, not a fixed list
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DERIVE HYPOTHESES
  → From what you found: which trust assumptions can I violate?
  → Which violations produce High/Critical impact on THIS target?
  → Rank by: (impact if exploited) × (likelihood of the assumption failing)
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HUNT — SEVERITY DESCENDING
  → Test hypotheses in impact-descending order
  → POC-or-kill at every step
  → Chain every finding before documenting it
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CHAIN
  → For every finding: what does this enable? What does it unlock?
  → A chain that elevates Medium to Critical is Critical
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MEDIUM / LOW (after High/Critical surface is exhausted)
  → Same mindset, lower impact bar
  → Same POC-or-kill rule
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REPORT
  → Confirmed findings only, full POC
  → Title, severity, steps, evidence, impact

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Chain Thinking — Before Closing Any Finding

What does this unlock that was not unlocked before?

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Context-Driven Priority Examples

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Minimum Reporting Standard

TITLE    — "[Vuln Type] on [endpoint/feature] allows [exact impact]"
SEVERITY — High or Critical (or Medium/Low with justification)
STEPS    — Numbered, copy-paste ready, reproducible by a stranger
EVIDENCE — Exact HTTP request + exact server response
IMPACT   — What an attacker achieves in business terms