takt/builtins/en/knowledge/security.md

Security Knowledge

AI-Generated Code Security Issues

AI-generated code has unique vulnerability patterns.

Pattern	Risk	Example
Plausible but dangerous defaults	High	cors: { origin: '*' } looks fine but is dangerous
Outdated security practices	Medium	Using deprecated encryption, old auth patterns
Incomplete validation	High	Validates format but not business rules
Over-trusting inputs	Critical	Assumes internal APIs are always safe
Copy-paste vulnerabilities	High	Same dangerous pattern repeated in multiple files

Require extra scrutiny:

• Auth/authorization logic (AI tends to miss edge cases)
• Input validation (AI may check syntax but miss semantics)
• Error messages (AI may expose internal details)
• Config files (AI may use dangerous defaults from training data)

Injection Attacks

SQL Injection:

• SQL construction via string concatenation → REJECT
• Not using parameterized queries → REJECT
• Unsanitized input in ORM raw queries → REJECT

// NG
db.query(`SELECT * FROM users WHERE id = ${userId}`)

// OK
db.query('SELECT * FROM users WHERE id = ?', [userId])

Command Injection:

• Unvalidated input in exec(), spawn() → REJECT
• Insufficient escaping in shell command construction → REJECT

// NG
exec(`ls ${userInput}`)

// OK
execFile('ls', [sanitizedInput])

XSS (Cross-Site Scripting):

• Unescaped output to HTML/JS → REJECT
• Improper use of innerHTML, dangerouslySetInnerHTML → REJECT
• Direct embedding of URL parameters → REJECT

Authentication & Authorization

Authentication issues:

• Hardcoded credentials → Immediate REJECT
• Plaintext password storage → Immediate REJECT
• Weak hash algorithms (MD5, SHA1) → REJECT
• Improper session token management → REJECT

Authorization issues:

• Missing permission checks → REJECT
• IDOR (Insecure Direct Object Reference) → REJECT
• Privilege escalation possibility → REJECT

// NG - No permission check
app.get('/user/:id', (req, res) => {
  return db.getUser(req.params.id)
})

// OK
app.get('/user/:id', authorize('read:user'), (req, res) => {
  if (req.user.id !== req.params.id && !req.user.isAdmin) {
    return res.status(403).send('Forbidden')
  }
  return db.getUser(req.params.id)
})

Data Protection

Sensitive information exposure:

• Hardcoded API keys, secrets → Immediate REJECT
• Sensitive info in logs → REJECT
• Internal info exposure in error messages → REJECT
• Committed .env files → REJECT

Data validation:

• Unvalidated input values → REJECT
• Missing type checks → REJECT
• No size limits set → REJECT

Cryptography

• Use of weak crypto algorithms → REJECT
• Fixed IV/Nonce usage → REJECT
• Hardcoded encryption keys → Immediate REJECT
• No HTTPS (production) → REJECT

File Operations

Path Traversal:

• File paths containing user input → REJECT
• Insufficient ../ sanitization → REJECT

// NG
const filePath = path.join(baseDir, userInput)
fs.readFile(filePath)

// OK
const safePath = path.resolve(baseDir, userInput)
if (!safePath.startsWith(path.resolve(baseDir))) {
  throw new Error('Invalid path')
}

File Upload:

• No file type validation → REJECT
• No file size limits → REJECT
• Allowing executable file uploads → REJECT

Dependencies

• Packages with known vulnerabilities → REJECT
• Unmaintained packages → Warning
• Unnecessary dependencies → Warning

Error Handling

• Stack trace exposure in production → REJECT
• Detailed error message exposure → REJECT
• Swallowing security events → REJECT

Rate Limiting & DoS Protection

• No rate limiting (auth endpoints) → Warning
• Resource exhaustion attack possibility → Warning
• Infinite loop possibility → REJECT

Multi-Tenant Data Isolation

Prevent data access across tenant boundaries. Authorization (who can operate) and scoping (which tenant's data) are separate concerns.

Criteria	Verdict
Reads are tenant-scoped but writes are not	REJECT
Write operations use client-provided tenant ID	REJECT
Endpoint using tenant resolver has no authorization control	REJECT
Some paths in role-based branching don't account for tenant resolution	REJECT

Read-Write Consistency

Apply tenant scoping to both reads and writes. Scoping only one side creates a state where data cannot be viewed but can be modified.

When adding a tenant filter to reads, always add tenant verification to corresponding writes.

Write-Side Tenant Verification

For write operations, use the tenant ID resolved from the authenticated user, not from the request body.

// NG - Trusting client-provided tenant ID
fun create(request: CreateRequest) {
    service.create(request.tenantId, request.data)
}

// OK - Resolve tenant from authentication
fun create(request: CreateRequest) {
    val tenantId = tenantResolver.resolve()
    service.create(tenantId, request.data)
}

Authorization-Resolver Alignment

When a tenant resolver assumes a specific role (e.g., staff), the endpoint must have corresponding authorization controls. Without authorization, unexpected roles can access the endpoint and cause the resolver to fail.

// NG - Resolver assumes STAFF but no authorization control
fun getSettings(): SettingsResponse {
    val tenantId = tenantResolver.resolve()  // Fails for non-STAFF
    return settingsService.getByTenant(tenantId)
}

// OK - Authorization ensures correct role
@Authorized(roles = ["STAFF"])
fun getSettings(): SettingsResponse {
    val tenantId = tenantResolver.resolve()
    return settingsService.getByTenant(tenantId)
}

For endpoints with role-based branching, verify that tenant resolution succeeds on all paths.

OWASP Top 10 Checklist

Category	Check Items
A01 Broken Access Control	Authorization checks, CORS config
A02 Cryptographic Failures	Encryption, sensitive data protection
A03 Injection	SQL, Command, XSS
A04 Insecure Design	Security design patterns
A05 Security Misconfiguration	Default settings, unnecessary features
A06 Vulnerable Components	Dependency vulnerabilities
A07 Auth Failures	Authentication mechanisms
A08 Software Integrity	Code signing, CI/CD
A09 Logging Failures	Security logging
A10 SSRF	Server-side requests