# Security And Hardening

> 加固代码以防漏洞。用于处理用户输入、认证、数据存储或外部集成时；用于构建任何接受不可信数据、管理用户会话或与第三方服务交互的功能时。

- Skill: `vinvcn/security-and-hardening` (Agent Skill)
- Install (CLI): `npx skillmds@latest add vinvcn/security-and-hardening`
- Raw SKILL.md: https://api.skillmd.com/api/skills/vinvcn/security-and-hardening/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: vinvcn (https://skillmd.com/u/vinvcn)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/vinvcn/security-and-hardening

---


# 安全和加固

## 概览

面向 Web 应用的安全优先开发实践。把每个外部输入都视为敌意输入，把每个 secret 都视为不可泄露，把每次授权检查都视为必需。安全不是一个阶段，而是触及用户数据、认证或外部系统的每一行代码都必须满足的约束。

## 何时使用

- 构建任何接受用户输入的东西
- 实现认证或授权
- 存储或传输敏感数据
- 集成外部 API 或服务
- 添加文件上传、webhooks 或 callbacks
- 处理支付或 PII 数据

## 三层边界系统

### 必须始终执行（无例外）

- **在系统边界验证所有外部输入**（API routes、form handlers）
- **参数化所有数据库查询**，绝不要把用户输入拼接进 SQL
- **编码输出** 以防止 XSS（使用框架自动转义，不要绕过它）
- **所有外部通信使用 HTTPS**
- **使用 bcrypt/scrypt/argon2 哈希密码**（绝不存储明文）
- **设置安全 header**（CSP、HSTS、X-Frame-Options、X-Content-Type-Options）
- **会话使用 httpOnly、secure、sameSite cookies**
- **每次发布前运行 `npm audit`**（或等价工具）

### 先询问（需要人工批准）

- 添加新的认证流程或修改 auth 逻辑
- 存储新的敏感数据类别（PII、支付信息）
- 添加新的外部服务集成
- 修改 CORS 配置
- 添加文件上传 handler
- 修改 rate limiting 或 throttling
- 授予提升后的权限或角色

### 绝不执行

- **绝不要将 secrets commit 到版本控制**（API keys、passwords、tokens）
- **绝不要记录敏感数据到日志**（passwords、tokens、完整信用卡号）
- **绝不要把客户端校验当作安全边界**
- **绝不要为了方便禁用安全 header**
- **绝不要对用户提供的数据使用 `eval()` 或 `innerHTML`**
- **绝不要把会话存储在客户端可访问的存储中**（auth tokens 放在 localStorage）
- **绝不要向用户暴露 stack traces** 或内部错误细节

## OWASP Top 10 防护

### 1. Injection（SQL、NoSQL、OS Command）

```typescript
// BAD: SQL injection via string concatenation
const query = `SELECT * FROM users WHERE id = '${userId}'`;

// GOOD: Parameterized query
const user = await db.query('SELECT * FROM users WHERE id = $1', [userId]);

// GOOD: ORM with parameterized input
const user = await prisma.user.findUnique({ where: { id: userId } });
```

### 2. Broken Authentication

```typescript
// Password hashing
import { hash, compare } from 'bcrypt';

const SALT_ROUNDS = 12;
const hashedPassword = await hash(plaintext, SALT_ROUNDS);
const isValid = await compare(plaintext, hashedPassword);

// Session management
app.use(session({
  secret: process.env.SESSION_SECRET,  // From environment, not code
  resave: false,
  saveUninitialized: false,
  cookie: {
    httpOnly: true,     // Not accessible via JavaScript
    secure: true,       // HTTPS only
    sameSite: 'lax',    // CSRF protection
    maxAge: 24 * 60 * 60 * 1000,  // 24 hours
  },
}));
```

### 3. Cross-Site Scripting (XSS)

```typescript
// BAD: Rendering user input as HTML
element.innerHTML = userInput;

// GOOD: Use framework auto-escaping (React does this by default)
return <div>{userInput}</div>;

// If you MUST render HTML, sanitize first
import DOMPurify from 'dompurify';
const clean = DOMPurify.sanitize(userInput);
```

### 4. Broken Access Control

```typescript
// Always check authorization, not just authentication
app.patch('/api/tasks/:id', authenticate, async (req, res) => {
  const task = await taskService.findById(req.params.id);

  // Check that the authenticated user owns this resource
  if (task.ownerId !== req.user.id) {
    return res.status(403).json({
      error: { code: 'FORBIDDEN', message: 'Not authorized to modify this task' }
    });
  }

  // Proceed with update
  const updated = await taskService.update(req.params.id, req.body);
  return res.json(updated);
});
```

### 5. Security Misconfiguration

```typescript
// Security headers (use helmet for Express)
import helmet from 'helmet';
app.use(helmet());

// Content Security Policy
app.use(helmet.contentSecurityPolicy({
  directives: {
    defaultSrc: ["'self'"],
    scriptSrc: ["'self'"],
    styleSrc: ["'self'", "'unsafe-inline'"],  // Tighten if possible
    imgSrc: ["'self'", 'data:', 'https:'],
    connectSrc: ["'self'"],
  },
}));

// CORS — restrict to known origins
app.use(cors({
  origin: process.env.ALLOWED_ORIGINS?.split(',') || 'http://localhost:3000',
  credentials: true,
}));
```

### 6. Sensitive Data Exposure

```typescript
// Never return sensitive fields in API responses
function sanitizeUser(user: UserRecord): PublicUser {
  const { passwordHash, resetToken, ...publicFields } = user;
  return publicFields;
}

// Use environment variables for secrets
const API_KEY = process.env.STRIPE_API_KEY;
if (!API_KEY) throw new Error('STRIPE_API_KEY not configured');
```

## 输入校验模式

### 在边界进行 Schema Validation

```typescript
import { z } from 'zod';

const CreateTaskSchema = z.object({
  title: z.string().min(1).max(200).trim(),
  description: z.string().max(2000).optional(),
  priority: z.enum(['low', 'medium', 'high']).default('medium'),
  dueDate: z.string().datetime().optional(),
});

// Validate at the route handler
app.post('/api/tasks', async (req, res) => {
  const result = CreateTaskSchema.safeParse(req.body);
  if (!result.success) {
    return res.status(422).json({
      error: {
        code: 'VALIDATION_ERROR',
        message: 'Invalid input',
        details: result.error.flatten(),
      },
    });
  }
  // result.data is now typed and validated
  const task = await taskService.create(result.data);
  return res.status(201).json(task);
});
```

### 文件上传安全

```typescript
// Restrict file types and sizes
const ALLOWED_TYPES = ['image/jpeg', 'image/png', 'image/webp'];
const MAX_SIZE = 5 * 1024 * 1024; // 5MB

function validateUpload(file: UploadedFile) {
  if (!ALLOWED_TYPES.includes(file.mimetype)) {
    throw new ValidationError('File type not allowed');
  }
  if (file.size > MAX_SIZE) {
    throw new ValidationError('File too large (max 5MB)');
  }
  // Don't trust the file extension — check magic bytes if critical
}
```

## 分流 npm audit 结果

不是所有 audit 发现都需要立即处理。使用这个决策树：

```
npm audit reports a vulnerability
├── Severity: critical or high
│   ├── Is the vulnerable code reachable in your app?
│   │   ├── YES --> Fix immediately (update, patch, or replace the dependency)
│   │   └── NO (dev-only dep, unused code path) --> Fix soon, but not a blocker
│   └── Is a fix available?
│       ├── YES --> Update to the patched version
│       └── NO --> Check for workarounds, consider replacing the dependency, or add to allowlist with a review date
├── Severity: moderate
│   ├── Reachable in production? --> Fix in the next release cycle
│   └── Dev-only? --> Fix when convenient, track in backlog
└── Severity: low
    └── Track and fix during regular dependency updates
```

**关键问题：**
- 存在漏洞的函数是否真的会在你的代码路径中被调用？
- 该依赖是 runtime dependency 还是 dev-only？
- 在你的部署上下文中，该漏洞是否可被利用（例如 client-only app 中的 server-side vulnerability）？

当你延期修复时，记录原因并设置 review date。

## Rate Limiting

```typescript
import rateLimit from 'express-rate-limit';

// General API rate limit
app.use('/api/', rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100,                   // 100 requests per window
  standardHeaders: true,
  legacyHeaders: false,
}));

// Stricter limit for auth endpoints
app.use('/api/auth/', rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 10,  // 10 attempts per 15 minutes
}));
```

## Secrets 管理

```
.env files:
  ├── .env.example  → Committed (template with placeholder values)
  ├── .env          → NOT committed (contains real secrets)
  └── .env.local    → NOT committed (local overrides)

.gitignore must include:
  .env
  .env.local
  .env.*.local
  *.pem
  *.key
```

**提交前始终检查：**
```bash
# Check for accidentally staged secrets
git diff --cached | grep -i "password\|secret\|api_key\|token"
```

## 安全审查检查清单

```markdown
### Authentication
- [ ] Passwords hashed with bcrypt/scrypt/argon2 (salt rounds ≥ 12)
- [ ] Session tokens are httpOnly, secure, sameSite
- [ ] Login has rate limiting
- [ ] Password reset tokens expire

### Authorization
- [ ] Every endpoint checks user permissions
- [ ] Users can only access their own resources
- [ ] Admin actions require admin role verification

### Input
- [ ] All user input validated at the boundary
- [ ] SQL queries are parameterized
- [ ] HTML output is encoded/escaped

### Data
- [ ] No secrets in code or version control
- [ ] Sensitive fields excluded from API responses
- [ ] PII encrypted at rest (if applicable)

### Infrastructure
- [ ] Security headers configured (CSP, HSTS, etc.)
- [ ] CORS restricted to known origins
- [ ] Dependencies audited for vulnerabilities
- [ ] Error messages don't expose internals
```
## 另请参阅

详细安全检查清单和 pre-commit 验证步骤见 `references/security-checklist.md`。

## 常见合理化借口

| 合理化借口 | 现实 |
|---|---|
| “这是内部工具，安全不重要” | 内部工具也会被攻破。攻击者会瞄准最薄弱环节。 |
| “以后再加安全” | 事后补安全比一开始就内建安全难 10 倍。现在就加。 |
| “没人会尝试利用这个” | 自动扫描器会发现它。Security by obscurity 不是安全。 |
| “框架会处理安全” | 框架提供工具，不提供保证。你仍然需要正确使用它们。 |
| “这只是原型” | 原型会变成生产系统。从第一天就养成安全习惯。 |

## 危险信号

- 用户输入直接传入数据库查询、shell commands 或 HTML rendering
- 源代码或 commit history 中有 secrets
- API endpoints 没有认证或授权检查
- 缺少 CORS 配置，或使用通配符（`*`）origins
- 认证 endpoints 没有 rate limiting
- Stack traces 或内部错误暴露给用户
- 依赖存在已知 critical 漏洞

## 验证

实现安全相关代码后：

- [ ] `npm audit` 没有 critical 或 high 漏洞
- [ ] 源代码或 git history 中没有 secrets
- [ ] 所有用户输入都在系统边界验证
- [ ] 每个受保护 endpoint 都检查认证和授权
- [ ] 响应中存在安全 header（用 browser DevTools 检查）
- [ ] 错误响应不暴露内部细节
- [ ] auth endpoints 已启用 rate limiting