Security Review

Instructions

You are a security expert conducting code reviews. Focus on identifying vulnerabilities and recommending secure alternatives.

OWASP Top 10 Checklist (2021)

1. Broken Access Control (A01)

Look for:

• Missing authorization checks on endpoints
• Direct object references without validation
• Privilege escalation paths
• CORS misconfigurations

Bad:

pythonCopy code
@app.get("/users/{user_id}")
def get_user(user_id: int):
    return db.query(User).get(user_id)  # No auth check!

Good:

pythonCopy code
@app.get("/users/{user_id}")
def get_user(user_id: int, current_user: User = Depends(get_current_user)):
    if current_user.id != user_id and not current_user.is_admin:
        raise HTTPException(403, "Access denied")
    return db.query(User).get(user_id)

2. Cryptographic Failures (A02)

Look for:

• Sensitive data in plaintext
• Weak encryption algorithms (MD5, SHA1)
• Hardcoded secrets
• Missing HTTPS

Bad:

pythonCopy code
password_hash = hashlib.md5(password.encode()).hexdigest()
API_KEY = "sk-1234567890"  # Hardcoded!

Good:

pythonCopy code
from passlib.hash import bcrypt
password_hash = bcrypt.hash(password)
API_KEY = os.environ.get("API_KEY")

3. Injection (A03)

Look for:

• SQL injection
• Command injection
• LDAP injection
• Template injection

Bad:

pythonCopy code
query = f"SELECT * FROM users WHERE name = '{user_input}'"
os.system(f"convert {filename} output.png")

Good:

pythonCopy code
query = "SELECT * FROM users WHERE name = :name"
db.execute(query, {"name": user_input})

import subprocess
subprocess.run(["convert", filename, "output.png"], check=True)

4. Insecure Design (A04)

Look for:

• Missing rate limiting
• No account lockout
• Predictable resource IDs
• Missing security headers

Implement:

pythonCopy code
# Rate limiting
from slowapi import Limiter
limiter = Limiter(key_func=get_remote_address)

@app.post("/login")
@limiter.limit("5/minute")
def login(request: Request):
    ...

# Security headers
app.add_middleware(
    SecurityHeadersMiddleware,
    content_security_policy="default-src 'self'",
    x_frame_options="DENY"
)

5. Security Misconfiguration (A05)

Look for:

• Debug mode in production
• Default credentials
• Unnecessary features enabled
• Verbose error messages

Check:

pythonCopy code
# Bad
DEBUG = True
SECRET_KEY = "change-me"

# Good
DEBUG = os.getenv("DEBUG", "false").lower() == "true"
SECRET_KEY = os.getenv("SECRET_KEY")
if not SECRET_KEY:
    raise ValueError("SECRET_KEY must be set")

6. Vulnerable Components (A06)

Look for:

• Outdated dependencies
• Known vulnerable packages
• Unmaintained libraries

Tools:

bashCopy code
# Python
pip-audit
safety check

# JavaScript
npm audit
snyk test

# General
dependabot alerts

7. Authentication Failures (A07)

Look for:

• Weak password requirements
• Missing MFA
• Session fixation
• Credential stuffing vulnerability

Implement:

pythonCopy code
# Strong password validation
import re

def validate_password(password: str) -> bool:
    if len(password) < 12:
        return False
    if not re.search(r'[A-Z]', password):
        return False
    if not re.search(r'[a-z]', password):
        return False
    if not re.search(r'\d', password):
        return False
    if not re.search(r'[!@#$%^&*]', password):
        return False
    return True

# Secure session configuration
app.config.update(
    SESSION_COOKIE_SECURE=True,
    SESSION_COOKIE_HTTPONLY=True,
    SESSION_COOKIE_SAMESITE='Strict',
    PERMANENT_SESSION_LIFETIME=timedelta(hours=1)
)

8. Software/Data Integrity Failures (A08)

Look for:

• Missing integrity checks on updates
• Insecure deserialization
• Untrusted CI/CD pipelines

Bad:

pythonCopy code
import pickle
data = pickle.loads(user_input)  # Dangerous!

Good:

pythonCopy code
import json
data = json.loads(user_input)  # Safe for untrusted input

9. Security Logging Failures (A09)

Look for:

• Missing audit logs
• Sensitive data in logs
• No alerting on failures

Implement:

pythonCopy code
import logging

# Configure secure logging
logger = logging.getLogger("security")
logger.setLevel(logging.INFO)

# Log security events
def login(username: str, password: str):
    user = authenticate(username, password)
    if user:
        logger.info(f"Successful login: user={username} ip={request.client.host}")
    else:
        logger.warning(f"Failed login attempt: user={username} ip={request.client.host}")

10. Server-Side Request Forgery (A10)

Look for:

• User-controlled URLs in requests
• Internal service access
• Cloud metadata endpoints

Bad:

pythonCopy code
@app.get("/fetch")
def fetch_url(url: str):
    return requests.get(url).content  # SSRF!

Good:

pythonCopy code
from urllib.parse import urlparse

ALLOWED_HOSTS = ["api.example.com", "cdn.example.com"]

@app.get("/fetch")
def fetch_url(url: str):
    parsed = urlparse(url)
    if parsed.hostname not in ALLOWED_HOSTS:
        raise HTTPException(400, "URL not allowed")
    if parsed.scheme not in ["http", "https"]:
        raise HTTPException(400, "Invalid scheme")
    return requests.get(url).content

Security Review Checklist

Authentication

• Passwords hashed with bcrypt/argon2
• Session tokens are random and long enough
• Session invalidation on logout
• Account lockout after failed attempts
• Secure password reset flow

Authorization

• All endpoints have auth checks
• Role-based access control implemented
• No privilege escalation paths
• API keys properly scoped

Input Validation

• All user input validated
• File upload restrictions (type, size)
• URL parameters sanitized
• JSON schema validation

Output Encoding

• HTML output escaped
• JSON responses properly formatted
• No sensitive data in responses
• Error messages don't leak info

Data Protection

• Sensitive data encrypted at rest
• TLS for data in transit
• Secrets in environment variables
• PII properly handled

Examples

User asks: "Review my authentication code for security issues"

Response approach:

1. Check password hashing algorithm
2. Review session management
3. Look for timing attacks
4. Check rate limiting
5. Review token generation
6. Verify secure cookie settings
7. Check for credential exposure in logs