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Bugcrowd-specific reporting tactics complementing report-writing: VRT category search-and-fallback strategy when no exact match exists, manual severity override when VRT defaults underrate impact, sev
The skill file stays in the publisher's repository.
Paste the copied command in a terminal. It installs this SKILL.md into that agent.
npx skills add elementalsouls/Claude-BugHunter --skill bugcrowd-reporting -a cursor -y
Bugcrowd-specific reporting tactics complementing report-writing: VRT category search-and-fallback strategy when no exact match exists, manual severity override when VRT defaults underrate impact, severity-request paragraph as first body section, OOS-clause rebuttal templates (rate limiting on auth-flow endpoints, debug-info framing, user-enumeration with sensitive PII, theoretical-issue counter), chained-finding cross-reference patterns, target selection for QA-vs-prod programs, researcher-side hygiene (Bugcrowdninja email alias, account state restoration, friendly-tester posture). Use when filing a Bugcrowd submission, when VRT default seems wrong, when triager closes as OOS or downgrades severity, when chaining linked submissions, or when scope distinguishes production from QA. Pairs with report-writing and triage-validation.
Bugcrowd-specific reporting tactics complementing report-writing: VRT category search-and-fallback strategy when no exact match exists, manual severity override when VRT defaults underrate impact, severity-request paragraph as first body section, OOS-clause rebuttal templates (rate limiting on auth-flow endpoints, debug-info framing, user-enumeration with sensitive PII, theoretical-issue counter), chained-finding cross-reference patterns, target selection for QA-vs-prod programs, researcher-side hygiene (Bugcrowdninja email alias, account state restoration, friendly-tester posture). Use when filing a Bugcrowd submission, when VRT default seems wrong, when triager closes as OOS or downgrades severity, when chaining linked submissions, or when scope distinguishes production from QA. Pairs with report-writing and triage-validation.
Companion to the generic
report-writingskill. Use when working specifically on Bugcrowd submissions where VRT mapping, OOS-clause rebuttals, or per-program target selection matter.
This skill encodes patterns that apply specifically to Bugcrowd's submission flow. For the generic per-platform templates (HackerOne / Bugcrowd / Intigriti / Immunefi report bodies), use the report-writing skill. For the 7-Question Gate before deciding to report at all, use triage-validation.
Bugcrowd's submission form requires a single VRT (Vulnerability Rating Taxonomy) selection. The dropdown's default severity is bound to the chosen node — pick wrong and the form auto-suggests a lower priority (often P4) when the actual impact is P3 or P2.
Note: VRT default severities are not fixed constants. Bugcrowd revises the VRT schema across versions, and individual programs can remap defaults via their own priority configuration. The P-values shown in the examples below (e.g., "No Rate Limiting on Form → Login" defaulting to P4) are the typical baseline at time of writing — always read the severity the current form actually auto-suggests for this program rather than assuming the value here.
For any finding, search the VRT dropdown with these terms in this order:
IDOR, XSS, SSRF, auth bypass, 2FA bypassPII, sensitive data exposure, disclosure of secretsbroken access control, authentication bypassno rate limiting on form > login, no rate limiting on form > change passwordServer Security Misconfiguration > Other, Broken Access Control > OtherNever select a VRT that misrepresents the bug just to get a higher default severity. Triagers will reassign and may flag the misrepresentation. The discipline is: pick the most specific accurate VRT, then use §2 (Manual Severity Override) if the default is wrong.
| Finding type | First-choice VRT | Fallback |
|---|---|---|
| ATO via missing 2FA on password change | Broken Authentication & Session Management → Second Factor Authentication (2FA/MFA) → Bypass | Broken Auth → Authentication Bypass → Other |
| Password oracle without rate limit | Broken Authentication & Session Management → Authentication Bypass → Other | Server Security Misconfiguration → No Rate Limiting on Form → Login |
| GraphQL introspection / APQ allowlist bypass | Server Security Misconfiguration → Other (justify in body) | Broken Access Control → Other |
| Username → real name PII enumeration | Sensitive Data Exposure → PII Leakage / Disclosure of Secrets → Non-Corporate User | Broken Access Control → Other |
| State desync on security-sensitive action | Application-Level DoS → Other (with state-desync framing) | Server Security Misconfiguration → Other |
| Email/SMS pumping on auth-flow endpoint | Server Security Misconfiguration → No Rate Limiting on Form → Email-Triggering / SMS-Triggering | Server Security Misconfiguration → No Rate Limiting on Action |
| Token brute-force (email-change OTP, password reset) | Broken Authentication → Authentication Bypass → Other | Server Security Misconfiguration → No Rate Limiting on Action |
Pick Server Security Misconfiguration → Other or Broken Access Control → Other and lead the description body with a "VRT mapping note" explaining why the chosen node is the closest available match and what the bug actually is.
Bugcrowd's form lets you manually set Technical Severity separate from the VRT default. The form text itself states: "A severity rating suggested by the VRT is not guaranteed to be the severity rating applied to your submission."
Override the VRT default when:
P1 inflation is the fastest way to lose triager trust. Reserve P1 for ATO without interaction, RCE, mass PII exfiltration, fund theft, and similar Critical-bucket impacts. If the chain to P1 requires a separate stolen-cookie premise, file the standalone primitive at P3 and discuss the chain explicitly with cross-references (per §4).
When the VRT default underrates impact, the FIRST section of the description body should be a severity-request paragraph. This is the first thing the triager reads and it pre-empts the auto-close that often happens when triagers see "P4" in the form.
## Severity request — please review carefully before applying VRT default
The closest VRT category for this finding is "[chosen VRT]," which Bugcrowd defaults to **P[N] ($X-$Y in [program]'s rubric)**. **I am requesting evaluation at P[M] [standalone | in chain with submission XXXX]** for the following reasons:
1. **[Impact axis 1]** — [specific reason this finding exceeds the VRT default's example]
2. **[Impact axis 2]** — [specific reason, often citing the program's own Focus Areas]
3. **[Impact axis 3]** — [specific reason, often comparing to historical bounty payouts for the same data class]
[Optional: one paragraph contrasting the VRT default's typical example with this finding's actual impact, e.g., "P4 = No Rate Limiting on Login Form" applies to ordinary login pages where brute force is bounded by lockout policies; this endpoint has neither lockout nor throttle.]
## Severity request — please review carefully before applying VRT default
The closest VRT category for this finding is "No Rate Limiting on Form → Login," which Bugcrowd defaults to **P4 ($XX–$YY in this program's rubric)**. **I am requesting evaluation at P3 standalone, P2 in chain with submission XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX** for the following reasons:
1. **[Endpoint] is a password-disclosure oracle, not a generic rate-limit gap.** The endpoint returns true/false for a supplied password — combined with cookie theft, it is the exact primitive an attacker uses to learn the victim's *durable* credential from a stolen *transient* session.
2. **The chained outcome is "Account Takeover,"** explicitly listed under the program → Focus Areas → Critical (P1) examples. This finding is one of two independent links that make that chain work; the other is submission XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX.
3. **The two findings have independent fix surfaces.** Per the program's "one fix = one bounty" rule they should be evaluated as two separate findings whose chain raises the joint severity.
The "P4 = No Rate Limiting on Login Form" default applies to ordinary login pages where brute-force is bounded by lockout policies. This endpoint has neither lockout nor throttle, and the result of brute force is the *user's actual password* (not a session) — making the impact significantly higher than the default VRT severity assumes.
Bugcrowd triagers sometimes auto-close findings by mapping them to an OOS clause without reading the report. Pre-empt this by including an In-scope justification section that quotes the OOS clause and explains why your finding doesn't fit it.
When the finding is on an authentication endpoint (login, password change, password verify, OTP verify, token validate):
## In-scope justification
The program OOS list excludes "Rate limiting or brute-force issues on **non-authentication** endpoints." `[endpoint name]` is the canonical authentication endpoint — it accepts a password/token/OTP and returns whether it matches the user's stored credential. By definition this is an authentication primitive. The OOS clause's "non-authentication" qualifier therefore does NOT apply.
When the finding involves schema disclosure that's actually a control bypass (e.g., GraphQL allowlist bypass exposing the mutation surface):
## In-scope justification
This is not a "debug information" finding. The [persisted-query allowlist | introspection gate | etc.] is acting as an authorization control on the [GraphQL surface | API tree | etc.]. The bypass converts that gate into a no-op — multiple [mutations | endpoints] become reachable that the official clients cannot invoke. The schema disclosure is incidental; the impact is **mutation-surface unlock**, not information leakage.
When the finding leaks more than just "this handle/email exists":
## In-scope justification
The program OOS list excludes "User Enumeration issues with **low-risk and insignificant** information being enumerated." The data leaked here is **neither low-risk nor insignificant**: it includes the matched user's [full real first name, last name, profile photo / SSN last 4 / phone number / etc.]. Real-[name | identity | etc.] knowledge is the same data class that gates the program's own [account-recovery flows / fraud-investigation interviews / support-call verification], which means this lookup directly defeats one of the program's own anti-fraud controls. This is PII disclosure, not handle enumeration.
When the finding's exploitability has been demonstrated end-to-end:
## In-scope justification
This finding is exploitable end-to-end as demonstrated in the PoC: [one-sentence summary of the proven exploitation path]. The PoC includes [N HTTP requests with redacted cookies | N screenshots | a sanitized HAR file | etc.] showing the attacker's session [reading victim data | changing victim credentials | etc.]. The OOS clause for "theoretical issues that are not exploitable, or can not be demonstrated as exploitable" does not apply.
If you only have an "API behavior" observation without a fully demonstrated exploitation path, the finding is theoretical. Don't file it. Capture the missing evidence (delivery confirmation, token-format inspection, cross-account victim data in response, etc.) and re-evaluate. Filing theoretical findings damages researcher reputation on the platform.
Many high-impact findings are chains of two or more standalone primitives (oracle + missing step-up = ATO). Bugcrowd's program rule: "Submit one vulnerability per report. If multiple vulnerabilities must be chained to demonstrate impact, you may include them together, but please clearly explain the chain."
In the chain consumer's body, near the top:
## Chain partners (filed as separate reports)
- **submission [UUID-1]** — [primitive 1: e.g., `me.verify_password` no rate limit]
- **submission [UUID-2]** — [primitive 2: e.g., GraphQL APQ allowlist bypass]
These primitives have independent fix surfaces and are filed separately per the program's "one fix = one bounty" rule. The chained impact described here requires both primitives to be exploited end-to-end.
In each primitive's body:
## Chain context
This finding is the [N]th of [M] independent primitives that together produce [impact, e.g., "permanent account takeover from a stolen session cookie"]. The full chain narrative and the chained severity (P1) are documented in submission [UUID]. This standalone report is at P3 reflecting the primitive's individual impact.
Programs that scope both production and QA assets (e.g., app.target.com vs. app-qa.target.com) require careful target selection.
| If you tested... | Pick this target | Why |
|---|---|---|
| Production app/API | The production target | Most accurate; signals the impact landed on real users |
| QA app/API (per program rules for non-US researchers) | The QA target (e.g., Sign In - (QA), Enrollment - (QA)) | Accurate per program rules; signals friendly tester |
| QA but no specific QA target exists | Closest matching production target with a clear QA disclaimer in the body | Triager will reassign correctly if needed |
| Cross-asset finding (multiple targets affected) | The asset where the bug originates / has the highest impact | Add list of other affected targets in the body |
## Notes for triagers
- Tested in the QA environment ([qa-host]) per the program's instruction for non-US researchers / per the program's QA-testing scope.
- Production may enforce additional controls that QA does not — please confirm whether the same resolver code path runs on production.
- All testing limited to my own QA test account; no other accounts were interacted with.
- Selected target: `[chosen-target]`. Selected VRT: `[chosen-VRT]`. Both selected as closest available matches; please reassign if more appropriate options exist.
These are program-rule items that affect submission quality even though they're not part of the report body itself.
Most Bugcrowd-managed programs ask researchers to use their @bugcrowdninja.com alias as the account email on the target. This flags traffic as friendly-tester to the target's fraud team. Steps:
[email protected])[email protected], etc.)After demonstrating any state-changing action (password change, email change, device removal, money transfer):
After submitting any report that includes session-cookie-derived evidence:
When you have multiple findings from a single engagement, the order matters.
Maintain a simple text file with each submission's UUID, severity, and one-line description. You'll reference these IDs across reports and during any subsequent triager dialogue.
| For this question / task | Use this skill |
|---|---|
| "Should I report this finding at all?" | triage-validation (7-Question Gate) |
| "What's the report body template for Bugcrowd?" | report-writing |
| "What VRT do I pick?" | This skill (bugcrowd-reporting) §1 |
| "How do I argue for higher severity?" | This skill §2-3 |
| "How do I rebut an OOS objection?" | This skill §4 |
| "How do I redact cookies / PII in screenshots?" | evidence-hygiene |
| "Where do I find the payload for this exploitation step?" | security-arsenal |
| "Where do I find recon probes for this asset class?" | offensive-osint |
This skill is small and focused. It does NOT duplicate content from report-writing (per-platform templates, CVSS scoring, downgrade counters, 60-second pre-submit checklist) — load both skills together when filing a Bugcrowd report. The two skills' content composes naturally because their boundaries are clean: report-writing is the body templates, bugcrowd-reporting is the program-specific tactics layered on top.
report-writing — Always load this skill alongside bugcrowd-reporting. Workflow primitive: report-writing provides the body skeleton; this skill layers VRT selection + severity-request paragraph + OOS-clause rebuttals on top of that skeleton.triage-validation — When deciding if a Bugcrowd-bound finding will pass triage. Workflow primitive: 7Q gate runs first; only validated findings reach this skill for VRT mapping.evidence-hygiene — When attaching screenshots / HARs to a Bugcrowd submission. Workflow primitive: Bugcrowd's private attachment system requires redacted evidence; route everything through evidence-hygiene before clicking attach.security-arsenal — When the PoC step needs payloads cited verbatim. Workflow primitive: the "Steps to Reproduce" section in this skill's report bodies pulls exact payloads from security-arsenal so the triager can paste-and-run.bb-methodology — When confirming engagement mode is bug-bounty (not red-team). Workflow primitive: PART 0 of bb-methodology answers "bug bounty?"; if yes AND the target is Bugcrowd, this skill becomes the reporting overlay.