{
  "ruleId": "S025",
  "name": "Always validate client-side data on the server",
  "description": "Ensure all client-side data is validated on the server. Client-side validation is not sufficient for security as it can be bypassed by attackers. Server-side validation is mandatory for data integrity and security.",
  "category": "security",
  "severity": "error",
  "languages": ["typescript", "javascript"],
  "tags": ["security", "validation", "server-side", "owasp", "input-validation"],
  
  "patterns": {
    "nestjs": {
      "missingValidationPipe": {
        "description": "NestJS routes missing ValidationPipe or DTO validation",
        "severity": "error"
      },
      "unsafeBodyUsage": {
        "description": "Using @Body() with 'any' type instead of validated DTO",
        "severity": "error"
      }
    },
    "express": {
      "directReqUsage": {
        "description": "Direct use of req.body/req.query/req.params without validation",
        "severity": "error"
      },
      "missingMiddleware": {
        "description": "Express routes missing validation middleware",
        "severity": "error"
      }
    },
    "sensitiveFields": {
      "clientTrusted": {
        "description": "Sensitive fields (userId, role, price, isAdmin) trusted from client",
        "severity": "error",
        "fields": ["userId", "user_id", "id", "role", "roles", "permissions", "price", "amount", "total", "cost", "isAdmin", "is_admin", "admin", "discount", "balance", "credits", "isActive", "is_active", "enabled", "status", "state"]
      }
    },
    "sqlInjection": {
      "stringConcatenation": {
        "description": "SQL queries using string concatenation or template literals with user input",
        "severity": "error"
      }
    },
    "fileUpload": {
      "missingValidation": {
        "description": "File uploads missing server-side validation (type, size, content)",
        "severity": "error"
      }
    }
  },

  "validationIndicators": [
    "ValidationPipe",
    "class-validator",
    "IsString", "IsInt", "IsEmail", "IsUUID", "IsOptional", "IsArray",
    "validateOrReject", "plainToClass",
    "joi.validate", "yup.validate", "zod.parse",
    "fileFilter", "mimetype", "file.size"
  ],

  "frameworkSupport": {
    "nestjs": {
      "patterns": ["@Controller", "@Post", "@Get", "@Put", "@Delete", "@Body()", "@nestjs/"],
      "validationMethods": ["ValidationPipe", "class-validator", "DTO"]
    },
    "express": {
      "patterns": ["express", "req.body", "req.query", "req.params", "app.post", "app.get"],
      "validationMethods": ["joi", "yup", "express-validator", "middleware"]
    }
  },

  "examples": {
    "violations": [
      {
        "code": "@Post('/checkout') checkout(@Body() body: any) { return this.service.checkout(body); }",
        "issue": "Using @Body() with 'any' type - vulnerable to parameter tampering"
      },
      {
        "code": "const { userId, discount } = req.body; const order = await this.service.create(userId, discount);",
        "issue": "Trusting sensitive fields (userId, discount) from client without validation"
      },
      {
        "code": "const query = `SELECT * FROM users WHERE id = ${req.params.id}`;",
        "issue": "SQL injection via string concatenation with user input"
      }
    ],
    "fixes": [
      {
        "code": "app.useGlobalPipes(new ValidationPipe({ whitelist: true, forbidNonWhitelisted: true }));",
        "description": "Configure ValidationPipe globally"
      },
      {
        "code": "@Post('/checkout') checkout(@Body() dto: CheckoutDto, @Req() req) { const userId = req.user.sub; }",
        "description": "Use DTO validation and get userId from authenticated session"
      },
      {
        "code": "const query = 'SELECT * FROM users WHERE id = ?'; await db.query(query, [req.params.id]);",
        "description": "Use parameterized queries"
      }
    ]
  },

  "owaspMapping": {
    "category": "A03:2021 – Injection",
    "subcategories": [
      "A04:2021 – Insecure Design",
      "A07:2021 – Identification and Authentication Failures"
    ],
    "description": "Validates that all user input is properly validated server-side to prevent injection attacks and parameter tampering"
  }
}