# Missing Authentication for Critical Function (CWE-306)

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

- Prevalence: 높음 자주 악용됨
- Impact: 높음 6개의 높은 심각도 규칙
- Prevention: 문서화됨 6개의 수정 예시

**OWASP:** Identification and Authentication Failures (A07:2021-Identification and Authentication Failures) - #7

## Description

As data traverses trust boundaries, the data should be validated before being processed. When authentication is not applied to critical functions, attackers can invoke these functions without proving their identity.

## Prevention

### Python

Add @login_required or @permission_required decorator to all protected views

Add authentication using FastAPI Depends() dependency injection

### Go

Add Echo JWT middleware to protect API endpoints

Add Fiber JWT middleware to protect API endpoints

Add JWT authentication middleware to protect API endpoints

### JavaScript

Add @UseGuards decorator with authentication guard at controller or method level

## Warning Signs

- [HIGH] View handles sensitive operations without authentication decorator
- [HIGH] Django views that should require authentication but lack
@login_required, @permission_required, or o
- [HIGH] Endpoint performs sensitive operations without Depends(get_current_user) or similar auth
- [HIGH] FastAPI endpoints that perform sensitive operations without
authentication via Depends() dependency 
- [HIGH] Gin application missing JWT authentication middleware
- [HIGH] NestJS endpoint has no @UseGuards() decorator for authentication

## Consequences

- 권한 획득
- 애플리케이션 데이터 읽기
- 애플리케이션 데이터 수정
- 승인되지 않은 코드 실행

## Mitigations

- 소프트웨어를 신뢰 수준이 다른 구성 요소로 나누세요
- 보안에 중요한 기능이 있는 모든 영역을 식별하고 해당 영역마다 인증을 요구하세요
- 적절한 접근 제어가 강제되도록 하세요

## Detection

- Total rules: 6
- Languages: python, go, typescript

## Rules by Language

### Go (3 rules)

- **Echo Missing JWT Middleware** [HIGH]: API endpoints lack JWT authentication middleware protection.
  - Remediation: Add JWT middleware to protect API routes.

```go
import "github.com/labstack/echo-jwt/v4"

api := e.Group("/api")
api.Use(echojwt.JWT([]byte(os.Getenv("JWT_SECRET"))))
api.POST("/transfer", transferHandler)
```

Learn more: https://shoulder.dev/learn/go/cwe-306/jwt-middleware
- **Fiber Missing JWT Middleware** [HIGH]: API endpoints lack JWT authentication middleware protection.
  - Remediation: Add JWT middleware to protect API routes.

```go
import "github.com/gofiber/contrib/jwt"

api := app.Group("/api")
api.Use(jwtware.New(jwtware.Config{
    SigningKey: jwtware.SigningKey{Key: []byte(os.Getenv("JWT_SECRET"))},
}))
api.Post("/transfer", transferHandler)
```

Learn more: https://shoulder.dev/learn/go/cwe-306/jwt-middleware
- **Gin Missing JWT Middleware** [HIGH]: API endpoints lack JWT authentication middleware protection.
  - Remediation: Add JWT middleware to protect API routes.

```go
import jwt "github.com/appleboy/gin-jwt/v2"

auth, _ := jwt.New(&jwt.GinJWTMiddleware{
    Realm: "api",
    Key:   []byte(os.Getenv("JWT_SECRET")),
})
api := r.Group("/api")
api.Use(auth.MiddlewareFunc())
api.POST("/transfer", transferHandler)
```

Learn more: https://shoulder.dev/learn/go/cwe-306/jwt-middleware

### Python (2 rules)

- **Django View Missing Authentication** [HIGH]: Detects Django views that should require authentication but lack
@login_required, @permission_required, or other authentication decorators.
  - Remediation: Add authentication:

```python
from django.contrib.auth.decorators import login_required, permission_required

@login_required
def protected_view(request):
    # Only authenticated users can access
    pass

@permission_required('app.change_model')
def admin_view(request):
    # Only users with permission can access
    pass
```
- **FastAPI Endpoint Missing Authentication** [HIGH]: Detects FastAPI endpoints that perform sensitive operations without
authentication via Depends() dependency injection.
  - Remediation: Add authentication via dependency injection:

```python
from fastapi import Depends, FastAPI
from fastapi.security import OAuth2PasswordBearer

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

async def get_current_user(token: str = Depends(oauth2_scheme)):
    # Verify token and return user
    return user

@app.delete("/users/{user_id}")
async def delete_user(
    user_id: int,
    current_user: User = Depends(get_current_user)  # Required auth
):
    # Only authenticated users can delete
    pass
```

### Typescript (1 rules)

- **NestJS Endpoint Missing Authentication Guard** [HIGH]: Endpoints without @UseGuards or @Public decorators are accessible to
unauthenticated users, enabling unauthorized access.
  - Remediation: Add @UseGuards decorator at controller or method level.

```typescript
import { UseGuards } from '@nestjs/common';
import { JwtAuthGuard } from '../auth/jwt-auth.guard';

@Controller('users')
@UseGuards(JwtAuthGuard)
export class UsersController {
  @Get(':id')
  findOne(@Param('id') id: string) {
    return this.usersService.findOne(id);
  }
}
```

Learn more: https://shoulder.dev/learn/typescript/cwe-306/missing-auth-guard