Security Scanner Skill

Purpose

Detects web application security vulnerabilities based on OWASP Top 10: XSS, hardcoded secrets, authentication issues.

When to Use

• Security scan requests
• XSS, CSRF, injection mentions
• Pre-production security review
• Auth/authz code review

Workflow

Step 1: Scan Scope

AskUserQuestion:

"Select scan scope"
Options:
- Frontend only
- Include API/backend
- Full project
- Specific file/folder

Step 2: Vulnerability Categories

AskUserQuestion:

"Select vulnerability types"
Options:
- Full security scan (recommended)
- XSS (Cross-Site Scripting)
- Secrets/API key exposure
- Auth/authz issues
- Dependency vulnerabilities
multiSelect: true

Security Rules

OWASP Top 10

Rank	Vulnerability	Check	Severity
A01	Broken Access Control	Auth bypass	CRITICAL
A02	Cryptographic Failures	Plaintext, weak crypto	CRITICAL
A03	Injection	SQL, NoSQL, XSS	CRITICAL
A05	Security Misconfiguration	CORS, headers	HIGH
A07	Auth Failures	Weak passwords, sessions	CRITICAL

XSS Detection

// CRITICAL: React dangerouslySetInnerHTML
<div dangerouslySetInnerHTML={{ __html: userInput }} />
// Fix: Use DOMPurify.sanitize(userInput)

// HIGH: innerHTML direct use
element.innerHTML = userInput
// Fix: Use textContent or sanitize

// CRITICAL: eval or Function constructor
eval(userCode)
new Function(userCode)()
// Fix: Never use

Secret Exposure

// CRITICAL: Hardcoded API key
const API_KEY = 'sk-1234567890abcdef'

// Patterns detected:
// - API keys: /[a-zA-Z0-9_-]{20,}/
// - AWS keys: /AKIA[0-9A-Z]{16}/
// - JWT: /eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+/

// Fix: Use environment variables
headers: { 'X-API-Key': process.env.NEXT_PUBLIC_API_KEY }

Auth/Authz Issues

// HIGH: Token in localStorage
localStorage.setItem('authToken', token)
// Fix: Use httpOnly cookies

// HIGH: Missing authorization check
async function deleteUser(userId) {
  await db.users.delete(userId) // No auth check
}
// Fix: Add authorization
if (!currentUser.isAdmin) throw new ForbiddenError()

Unsafe Data Handling

// HIGH: SQL Injection
const query = `SELECT * FROM users WHERE id = ${userId}`
// Fix: Parameterized query
const query = 'SELECT * FROM users WHERE id = $1'

// HIGH: Path traversal
const filePath = path.join(baseDir, userInput)
// Fix: Validate path
if (!safePath.startsWith(baseDir)) throw new Error()

Next.js/React Security

// HIGH: Server Action without validation
'use server'
async function updateProfile(formData) {
  const name = formData.get('name')
  await db.users.update({ name }) // No validation
}
// Fix: Use zod validation
const schema = z.object({ name: z.string().min(1).max(100) })

Response Template

## Security Scan Results

**Project**: [name]
**Files Scanned**: X

### CRITICAL (Immediate action)

#### 1. [A03] XSS Vulnerability
**File**: `src/components/Comment.tsx:45`
**Code**:
\`\`\`tsx
<div dangerouslySetInnerHTML={{ __html: comment.body }} />
\`\`\`
**Risk**: User input rendered without sanitization
**Fix**:
\`\`\`tsx
import DOMPurify from 'dompurify'
<div dangerouslySetInnerHTML={{ __html: DOMPurify.sanitize(comment.body) }} />
\`\`\`

### HIGH | MEDIUM | LOW
...

### Summary
| Severity | Count |
|----------|-------|
| CRITICAL | 2 |
| HIGH | 3 |
| MEDIUM | 5 |

### Actions
1. [ ] Install DOMPurify: `npm install dompurify`
2. [ ] Move API keys to .env
3. [ ] Use httpOnly cookies instead of localStorage

Best Practices

1. Least Privilege: Grant only necessary permissions
2. Defense in Depth: Validate at multiple layers
3. Input Validation: Validate all user input
4. Output Encoding: Context-appropriate encoding
5. Secret Management: Use env vars or secret managers

Integration

• code-reviewer skill
• nextjs-reviewer skill
• /analyze-code command

Notes

• Static analysis may have false positives
• Runtime security testing needs separate tools
• Sensitive files (.env, credentials) excluded from scan