mitm-find-bizlogic（中间人找到 bizlogic）

Find Business Logic Vulnerabilities

Analyze the mitmproxy dump (log.txt) for business logic flaws for: $ARGUMENTS

Requires: log.txt in the current directory. If it's missing, capture traffic first: ``bash mitmdump --set flow_detail=3 2>&1 | tee log.txt ``

High-Value Business Logic Patterns (from 376 real HackerOne bounty reports)

1. Payment/Pricing Manipulation

Real examples from bounties:

• Uber: paymentProfileUUID bypass for free rides
• Negative quantity for refund abuse
• Price manipulation in cart
• Coupon/promo code stacking
• Currency conversion abuse

Search patterns:

grep -iE '(price|amount|total|cost|fee|discount|coupon|promo|payment)' log.txt
grep -iE '(quantity|qty|count|num)[=:]["'\'']?-?[0-9]+' log.txt

2. Account/Email Verification Bypass

Real examples:

• Acronis: Account takeover via unverified email change
• Email change without verification
• Phone verification bypass
• Account deletion incomplete

Search patterns:

grep -iE '(verify|confirm|validate|activate|email|phone)' log.txt
grep -iE '(change|update).*(email|phone|password)' log.txt

3. Rate Limit/Brute Force Bypass

Real examples:

• No rate limiting on OTP verification
• Bypassing login attempt limits
• Parallel request exploitation
• CAPTCHA bypass via API

Search patterns:

grep -iE '(otp|code|pin|token|verify)' log.txt
grep -iE '(limit|rate|attempts|retry|captcha)' log.txt

4. Race Conditions

Real examples:

• Double-spending in wallet
• Concurrent coupon redemption
• Parallel transfer requests
• Vote manipulation via racing

Look for:

- Financial transactions (transfer, payment, redeem)
- Limited resource operations (claim, reserve, book)
- State-changing operations (status update, approve)

5. Workflow/State Bypass

Real examples:

• Skip steps in multi-step process
• Access feature without subscription
• Bypass approval workflow
• Manipulate exam/quiz results

Search patterns:

grep -iE '(step|stage|phase|status|state|workflow|approve)' log.txt
grep -iE '(submit|complete|finish|process)' log.txt

Vulnerability Categories & Severity

Testing Methodology

Step 1: Map Business Flows

# Find transaction-related endpoints
grep -iE 'POST.*(order|payment|checkout|cart|purchase|subscribe|redeem)' log.txt

# Find state-changing endpoints
grep -iE 'POST.*(update|change|modify|set|create|delete)' log.txt

# Find verification flows
grep -iE '(verify|confirm|validate|check|otp|code)' log.txt

Step 2: Test Parameter Manipulation

# Price manipulation
# Original: {"price": 100, "quantity": 1}
# Test: {"price": 1, "quantity": 1}
# Test: {"price": 100, "quantity": -1}

# Status manipulation
# Original: {"status": "pending"}
# Test: {"status": "approved"}

# Role manipulation
# Original: {"plan": "free"}
# Test: {"plan": "premium"}

Step 3: Test Race Conditions

# Send concurrent requests
for i in {1..10}; do
  curl -X POST 'https://target.com/api/redeem' -d '{"code":"PROMO123"}' &
done
wait

# Check if code was redeemed multiple times

Step 4: Test Workflow Bypass

# Skip step 2, go directly to step 3
curl 'https://target.com/api/checkout/step3' -d '{"order_id":"123"}'

# Access premium without subscription
curl 'https://target.com/api/premium/feature' -H 'Cookie: free_user_session'

Real Attack Scenarios

Scenario 1: Free Rides via Payment Profile Bypass

1. Capture ride request with paymentProfileUUID
2. Remove or modify paymentProfileUUID field
3. Server doesn't validate, processes ride without payment
4. Unlimited free rides

Scenario 2: Account Takeover via Email Change

1. Victim signs up with email but doesn't verify
2. Attacker changes email via API (no verification required)
3. Attacker now controls account with their email
4. Reset password → full takeover

Scenario 3: Coupon Race Condition

1. Find single-use coupon worth $100
2. Send 10 concurrent redeem requests
3. Race condition allows multiple redemptions
4. Get $1000 discount instead of $100

Scenario 4: Exam Score Manipulation

1. Take online exam, submit answers
2. Intercept response with score
3. Find score calculation endpoint
4. Replay with modified answers or directly set score

Parameters to Manipulate

Financial Parameters

price, amount, total, subtotal, tax
discount, discount_percent, coupon_value
quantity, qty, count, num
currency, currency_code
payment_method, payment_id
tip, fee, shipping_cost

Status/State Parameters

status, state, phase, step
is_verified, is_active, is_premium
approved, confirmed, completed
role, plan, tier, subscription

Identity Parameters

user_id, account_id, profile_id
email, phone, username
referral_code, invite_code

Output Format

## Business Logic Finding: [Brief Description]

**Endpoint**: `METHOD https://target.com/path`
**Flow**: [Payment|Registration|Verification|Workflow]
**Severity**: [CRITICAL|HIGH|MEDIUM|LOW]

**Normal Flow**:
1. User does X
2. Server validates Y
3. Action Z occurs

**Exploit Flow**:
1. User does X
2. User manipulates [parameter]
3. Server fails to validate
4. Unauthorized action occurs

**Evidence**:
[Request/response showing manipulation]

**Impact**:
- Financial loss of $X per abuse
- Account compromise
- Unauthorized access to premium features

**Test Command**:
curl -X POST 'https://target.com/...' -d '{"manipulated":"value"}'

**Remediation**:
- Server-side validation of all parameters
- Signed/encrypted values for sensitive data
- Idempotency keys for financial operations
- Rate limiting on sensitive endpoints

False Positives to Ignore

• Client-side only calculations (validated server-side)
• Parameters that return error when manipulated
• Debug/test endpoints in non-production
• Rate limits that are intentionally lenient
• Features that are intentionally free/accessible