Bug Bounty Report Writing

---

## CVSS 3.1 QUICK SCORING

### Formula

### Metric Quick Picks

| Metric | Value | Weight | When |
|---|---|---|---|
| **Attack Vector (AV)** | Network | +0.85 | Via internet |
| | Local | +0.55 | Local access needed |
| **Attack Complexity (AC)** | Low | +0.77 | Repeatable |
| | High | +0.44 | Race/timing needed |
| **Privileges Required (PR)** | None | +0.85 | No login |
| | Low | +0.62 | Regular user account |
| | High | +0.27 | Admin account |
| **User Interaction (UI)** | None | +0.85 | No victim action |
| | Required | +0.62 | Victim must click |
| **Scope (S)** | Changed | higher | Affects browser/OS/other |
| | Unchanged | lower | Stays in app |
| **Confidentiality (C)** | High | +0.56 | All data exposed |
| | Low | +0.22 | Limited data |
| **Integrity (I)** | High | +0.56 | Can modify any data |
| **Availability (A)** | High | +0.56 | Crashes service |

### Typical Scores by Bug Class

| Bug | Typical CVSS | Severity |
|---|---|---|
| IDOR (read PII) | 6.5 | Medium |
| IDOR (write/delete) | 7.5 | High |
| Auth bypass → admin | 9.8 | Critical |
| Stored XSS (any user) | 5.4–8.8 | Med–High |
| SQLi (data exfil) | 8.6 | High |
| SSRF (cloud metadata) | 9.1 | Critical |
| Race condition (double spend) | 7.5 | High |
| GraphQL auth bypass | 8.7 | High |
| JWT none algorithm | 9.1 | Critical |

---

## SEVERITY DECISION GUIDE

### Critical (P1)
- Full account takeover of any user without interaction
- Remote code execution
- SQLi with ability to dump/modify entire DB
- Auth bypass to admin panel
- SSRF to cloud metadata → IAM credentials exfil

### High (P2)
- Mass PII exposure (email, phone, SSN, payment data)
- Privilege escalation from user to admin
- SSRF reaching internal services (data returned)
- Stored XSS executing for all users of sensitive feature
- Payment bypass / financial loss without limit

### Medium (P3)
- IDOR on specific user's non-critical data
- XSS on low-sensitivity page requiring victim interaction
- CSRF on important but non-critical action
- Rate limit bypass on OTP (with effort demonstrated)

### Low (P4)
- Information disclosure (non-sensitive, no PII)
- Clickjacking on sensitive action WITH working PoC
- CORS on limited data

---

## SEVERITY SELF-ASSESSMENT

Each YES raises severity:

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## DOWNGRADE COUNTERS

| Program Says | Counter With |
|---|---|
| "Requires authentication" | "Attacker needs only a free account — no special role or permission" |
| "Limited impact" | "Affects [N] users / exposes [PII type] / $[amount] at risk" |
| "Already known" | "Show me the report number — I searched hacktivity and found none" |
| "By design" | "Show me the documentation stating this is intended behavior" |
| "Low CVSS" | "CVSS doesn't capture business impact — attacker can extract [X] in [Y] minutes" |
| "Not exploitable" | "Here is the exact response showing victim's data returned to attacker session" |

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## THE 60-SECOND PRE-SUBMIT CHECKLIST

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## CVSS 4.0 QUICK REFERENCE (newer programs)

CVSS 4.0 replaced CVSS 3.1 in November 2023. Some newer programs require it.

### Key Differences from CVSS 3.1

| Metric | CVSS 3.1 | CVSS 4.0 |
|---|---|---|
| Attack Vector | Network/Adjacent/Local/Physical | Same |
| Attack Complexity | Low/High | Low/High |
| **NEW**: Attack Requirements | (didn't exist) | None/Present (replaces some PR/UI) |
| Privileges Required | None/Low/High | Same |
| User Interaction | None/Required | None/Passive/Active |
| Scope | Unchanged/Changed | REMOVED |
| **NEW**: Sub-Impact metrics | (didn't exist) | Vulnerable/Subsequent system impact |

### CVSS 4.0 Score Examples

| Finding | CVSS 4.0 Score | Vector |
|---|---|---|
| Unauthenticated RCE | 10.0 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
| IDOR read PII, auth required | 6.9 | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N |
| Stored XSS, admin views it | 8.2 | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N |
| SSRF → cloud metadata | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:N |

### Quick CVSS 4.0 Calculator

**Practical rule**: If program uses CVSS 4.0 and you don't know the vector, use the calculator and include the full string starting with `CVSS:4.0/AV:...`. Programs cannot dispute a valid vector string.

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## HUMAN TONE GUIDELINES

**Write to a person, not a system:**
- Triagers are tired. Get to the impact in sentence 1.
- Use "I" not "the researcher" — you found it, own it
- Short paragraphs, bullet points for steps
- Hyperlink relevant docs if needed

**Escalation language (when payout is being downgraded):**

**Avoid:**
- Jargon the triager might not know
- 5-paragraph explanations of what IDOR is (they know)
- Theoretical chains ("could be combined with X to...")
- Passive voice ("it was observed that...")
- Qualifying language ("seems to," "appears to")

---

## STEPS TO REPRODUCE FORMAT (triager-optimized)

```markdown
**Setup:**
- Account A (attacker): email=attacker@test.com, ID=111
- Account B (victim): email=victim@test.com, ID=222
- Both created via normal registration — no special access

**Steps:**

1. Log in as Account A
2. Send this request (replace `111` with victim ID `222`):

\```
GET /api/v2/resource/222 HTTP/1.1
Host: target.com
Authorization: Bearer ACCOUNT_A_TOKEN
\```

3. Response contains Account B's private data:

\```json
{"id": 222, "email": "victim@test.com", "name": "Victim User", "address": "..."}
\```

**Expected:** 403 Forbidden
**Actual:** 200 OK with victim's private data