Securing Phoenix Applications
Phoenix is a popular web development framework written in Elixir that follows the model-view-controller pattern. As with any web application, security is a major concern when building Phoenix apps. Here are some best practices for securing Phoenix applications from common vulnerabilities and attacks:
Use Authentication
Don’t allow unauthenticated access to sensitive controller actions. Use a authentication solution like Ueberauth to require users to log in. Ueberauth makes it easy to integrate OAuth authentication with providers like Google, Facebook, GitHub, etc. For user passwords, be sure to use a secure hashing algorithm like bcrypt.
Prevent Cross-Site Scripting (XSS)
Escape dynamic data on output to prevent XSS attacks. Phoenix HTML and JSON views will do this automatically. Validate and sanitize any user input before inserting it into the database.
Authorize Resource Access
Use authorization to prevent users from accessing resources they don’t have permission for. Libraries like bodyguard or cancan make it easy to declare and enforce authorization rules.
Encrypt Sensitive Data
Use encryption via libraries like cryptox or ex_crypto to protect any sensitive data like passwords or API keys. Don’t store unencrypted sensitive data in your repository.
SQL Injection Protection
Use Ecto’s parameterized queries via the safe helper to prevent SQL injection attacks. Never construct raw SQL queries by string concatenation.
Secure Cookies
Enable the `:encrypted` and `:signed` options on Phoenix cookies. Use the `:http_only` option to prevent access from client-side JavaScript.
Content Security Policy
Use a Content Security Policy (CSP) response header to prevent XSS and data injection attacks. The CSP header allows listing approved sources for content like JavaScript, CSS, images, etc.
HTTPS Only
Redirect all HTTP traffic to HTTPS to prevent man-in-the-middle attacks. Enable HTTP Strict Transport Security (HSTS) to tell browsers to always access the site over HTTPS.
Other Tips
– Use tools like Credo, Dialyzer, and Coverex to detect security issues in your code.
– Separate production secrets from source code like API keys.
– Enable CSRF protection on forms
Monitoring for Security Issues
In addition to building secure Phoenix apps from the start, you also need to monitor production apps for security issues:
– Use error tracking like Sentry to detect and fix failures due to unintended states or bad input
– Monitor logs for signs of unauthorized access or injection attacks
– Set up anomaly detection to identify unusual spikes in traffic, data access, errors, etc which could indicate an attack
– Periodically test for vulnerabilities by running penetration tests, security audits, etc
Staying Up-to-Date on Security Best Practices
As new vulnerabilities and attack methods emerge, it’s important to stay up-to-date on security best practices:
– Monitor sites like US-CERT, OWASP, and CVE Details for new vulnerability announcements
– Follow security experts and organizations on social media to learn about new threats
– Attend security-focused conferences and training to learn the latest techniques
– Perform regular security audits on your Phoenix apps to check against current best practices
Conclusion
By following security best practices, monitoring your apps, and staying up-to-date, you can build robust Phoenix applications that protect user data and prevent attacks. Defense in depth is key – use multiple complementary security techniques like encryption, authorization, authentication, input validation and more. With vigilance and proper precautions, you can develop Phoenix apps that are secure and resilient.
Using Libraries to Enforce Security Policies
Rather than building security measures from scratch, it’s recommended to use established Elixir libraries that provide protections:
CSRF Protection
Use a library like OWASP’s Plug.CSRFProtection to protect Phoenix forms and state-changing endpoints from cross-site request forgery. It provides easy to use plugs to verify CSRF tokens.
Authentication
For authentication use a tested library like Comeonin which provides password hashing via bcrypt, argon2 and pbkdf2. For OAuth authentication use Oauth2 which supports being an OAuth provider and client.
Authorization
Manage authorization with Canary which allows declaring and enforcing granular authorization rules. Canary integrates with Plug for easy authorization of Phoenix endpoints.
Monitoring for OWASP Top 10 Vulnerabilities
The OWASP Top 10 outlines the most critical web application vulnerabilities. Be sure to monitor Phoenix apps for these common issues:
Injection Attacks
Use static analysis tools like Credo and Dialzyer to detect injection vulnerabilities by inspecting code. Monitor for sudden spikes in error rates that could indicate exploitation.
Broken Authentication
Audit authentication code to ensure proper password hashing, secure cookies, logout, timeouts, etc. Perform penetration testing to confirm defenses are working.
Sensitive Data Exposure
Review code to verifyproper use of encryption for sensitive data. Check that secrets are not exposed via logging, error messages, etc.
XML External Entities Injection
If accepting XML input, use a well-vetted XML parser and sanitize input. Monitor for extremely large XML entity payloads.
Applying Security Updates
Ensure Phoenix apps stay up-to-date with the latest security fixes:
Phoenix Framework
Track Phoenix updates and apply security fixes promptly when new Phoenix versions are released.
Dependencies
Use tools like Dependabot to automatically open PRs when dependencies need security updates. Quickly review and merge these PRs.
OS and Infrastructure
Apply timely security updates to operating systems, web servers, databases, etc. Consider immutable infrastructure to speed deployment of fresh patched images.
Security Training for Developers
Implement regular security training to teach Phoenix developers:
– OWASP Top 10 and other common vulnerabilities
– Using libraries and frameworks securely
– Proper error handling and logging
– Threat modeling to identify risks
– Input validation and output encoding
– Importance of upgrades, patches and monitoring
Focused security training will equip teams to build more secure software.
Conclusion
Security requires vigilance – use tools and libraries to enforce good practices, monitor for new threats, apply patches quickly, and ensure teams have proper training. A proactive approach to security will help protect Phoenix applications and users.
