Credential Stuffing in Nestjs

Credential stuffing in Nestjs applications typically exploits the framework's authentication and session management patterns. Attackers leverage valid username/password combinations from data breaches to systematically test login endpoints across multiple Nestjs services.

The most common attack vector targets Nestjs's built-in authentication guards. Consider a typical Nestjs login controller:

@Controller('auth')
export class AuthController {
  constructor(private readonly authService: AuthService) {}

  @UseGuards(LocalAuthGuard)
  @Post('login')
  async login(@Request() req) {
    return this.authService.login(req.user);
  }
}

Without rate limiting, an attacker can programmatically send thousands of requests per minute to this endpoint. Nestjs's default behavior allows unlimited authentication attempts, making it vulnerable to credential stuffing attacks that test common password combinations or use breached credential lists.

Session fixation attacks represent another credential stuffing pattern. When Nestjs applications use session-based authentication without proper session management:

@Injectable()
export class AuthService {
  async login(user: User) {
    const payload = { username: user.username, sub: user.id };
    return this.jwtService.sign(payload);
  }
}

Attackers can hijack sessions if JWT tokens aren't properly invalidated on logout or if session rotation isn't implemented. The lack of account lockout mechanisms after multiple failed attempts creates ideal conditions for credential stuffing.

Third-party authentication integrations also introduce credential stuffing risks. When Nestjs applications integrate with OAuth providers or use passport strategies:

@Injectable()
export class GoogleStrategy extends PassportStrategy(Strategy) {
  constructor() {
    super({
      clientID: process.env.GOOGLE_CLIENT_ID,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET,
      callbackURL: '/auth/google/callback'
    });
  }
}

Attackers may exploit weaknesses in the OAuth flow or target the callback endpoints where authentication state is managed.

Detecting credential stuffing in Nestjs requires monitoring authentication patterns and implementing detection mechanisms. middleBrick's API security scanner can identify Nestjs-specific credential stuffing vulnerabilities through several methods.

The scanner examines authentication endpoints for missing rate limiting controls. For Nestjs applications using @nestjs/passport, middleBrick tests whether login endpoints accept unlimited requests:

POST /auth/login HTTP/1.1
Content-Type: application/json

{