# Business Logic Errors (CWE-840)

The product does not properly implement the business logic rules, which may allow users to manipulate the system in unintended ways.

**Stack:** JavaScript

- Prevalence: Media 3 lenguajes cubiertos
- Impact: Alto 3 reglas de severidad alta
- Prevention: Documentada 3 ejemplos de corrección

**OWASP:** Broken Access Control (A01:2021-Broken Access Control) - #1

## Description

Business logic errors occur when the application's implementation doesn't correctly enforce the intended business rules. Unlike technical vulnerabilities, these are flaws in the application's design or logic.

## Prevention

Estrategias de prevención para Business Logic Errors basadas en 1 reglas de detección de Shoulder.

### JavaScript

Calculate totals and prices server-side using database values instead of client-submitted data

## Warning Signs

- [HIGH] client-controlled prices or amounts flowing to payment operations without server-side validation

## Consequences

- Eludir mecanismo de protección
- Obtener privilegios
- Modificar datos de la aplicación

## Mitigations

- Documenta claramente las reglas de negocio y sus implicaciones de seguridad
- Prueba casos límite y flujos de trabajo inusuales
- Implementa validación del lado del servidor de todas las reglas de negocio

## Detection

- Total rules: 3
- Languages: go, javascript, typescript, python

## Rules by Language

### Javascript (1 rules)

- **Business Logic Bypass** [HIGH]: Detects client-controlled prices or amounts flowing to payment operations without server-side validation.
  - Remediation: Calculate totals server-side using database prices.

```javascript
const product = await Product.findById(productId);
const total = product.price * quantity;
await stripe.charges.create({ amount: total, currency: 'usd' });
```

Learn more: https://shoulder.dev/learn/javascript/cwe-840/business-logic-bypass

### Typescript (1 rules)

- **Business Logic Bypass** [HIGH]: Detects client-controlled prices or amounts flowing to payment operations without server-side validation.
  - Remediation: Calculate totals server-side using database prices.

```javascript
const product = await Product.findById(productId);
const total = product.price * quantity;
await stripe.charges.create({ amount: total, currency: 'usd' });
```

Learn more: https://shoulder.dev/learn/javascript/cwe-840/business-logic-bypass