Writing Secure PHP Applications

Being secure on the web is getting harder and harder - the attacks are happening more and more and we, as web app developers, have to respond. The session will share tips you can follow in your code to ensure that your app stays safe and some tips to help improve investigation and preventing your app from becoming the next statistic.

Transcript

1. Writing Secure PHP Applications Chris Cornutt Confoo 2013 @enygma Wednesday, February 27, 2013
2. Secure development is broken. Let’s fix that... Wednesday, February 27, 2013
3. SQL injection is ten years old. XSS is eleven years old. why are they still a problem? Wednesday, February 27, 2013
4. Confidentiality Integrity Availability Wednesday, February 27, 2013
5. Confidentiality Integrity Availability Wednesday, February 27, 2013
6. Confidentiality Integrity Availability Wednesday, February 27, 2013
7. Confidentiality Integrity Availability Wednesday, February 27, 2013
8. We need to fix [insert exploit name here] Wednesday, February 27, 2013
9. WRONG Wednesday, February 27, 2013
10. Build security in from the start Wednesday, February 27, 2013
11. Security Standards Wednesday, February 27, 2013
12. Security Standards Security Testing Wednesday, February 27, 2013
13. Security Standards Security Testing Threat Modeling Wednesday, February 27, 2013
14. Security Standards Security Testing Threat Modeling Secure Architecture Wednesday, February 27, 2013
15. Security 101 Wednesday, February 27, 2013
16. Defense in Depth Wednesday, February 27, 2013
17. Reduce Attack Surface Wednesday, February 27, 2013
18. Effective Auditing & Logging Wednesday, February 27, 2013
19. Simple > Complex Wednesday, February 27, 2013
20. Obscurity !== Security Wednesday, February 27, 2013
21. And now, the specifics... Wednesday, February 27, 2013
22. Input validation <?php /* Using built-in */ is_numeric(‘1234’); // true ctype_digit(‘1234’); // false filter_var(‘invalid.email.com’, FILTER_VALID_EMAIL); // false /* Using 3rd party */ use Respect\Validation\Validator as v; $validator = v::alnum->noWhitespace->length(1,15); var_dump($validator->validate(‘thisisatest’); // true ?> https://github.com/Respect/Validation Wednesday, February 27, 2013
23. Return fast <?php /* Bad practice */ function foo($bar) { if ($bar == true) { /* Lots of code here... */ } else { return false; } } //----------------------------------- /* Good practice */ function foo($bar) { if ($bar !== true) { return false; } /* Lots of code here... */ } ?> Wednesday, February 27, 2013
24. Password hashing <?php /* in PHP 5.5+ */ $hash = password_hash($password, PASSWORD_BCRYPT, [‘cost’ => 12]); /* Prior to PHP 5.5+ */ $lib = new \PasswordLib\PasswordLib(); $hash = $lib->createPasswordHash($input); \phpSec\Crypt\Hash::$_method = \phpSec\Crypt\Hash::BCRYPT; $hash = \phpSec\Crypt\Hash::create($input); $bcrypt = new \Zend\Crypt\Password\Bcrypt(); $hash = $bcrypt->create($input); ?> https://github.com/icrmaxell/password_compat Wednesday, February 27, 2013
25. Encrypted sessions <?php /* Set custom session handler */ session_set_save_handler( ‘open’, ‘close’, ‘read’, ‘write’, ‘destroy’, ‘gc’ ); /* Using the handler interface */ class CustomSessionHandler extends SessionHandlerInterface { /* Code goes here */ } $handler = new CustomSessionHandler(); session_set_save_handler($handler, true); ?> https://github.com/enygma/shieldframework/blob/master/Shield/Session.php Wednesday, February 27, 2013
26. Least privilege <?php /* “Fail fast” for user handling */ function checkAccess($user, $resource) { if (!$user->allowed($resource) { return false; } /* Other permission checking here */ } /* “Fail least” for user handling */ function checkAccess($user, $resource) { if ($user == null) { return false; } if ($resource == null) { return false; } /* Other permission checking here */ } ?> Wednesday, February 27, 2013
27. Fail securely <?php /* Custom error handler */ set_error_handler(function($num, $str, $file, $line) { echo ‘ERROR: [‘.$num.’] ‘.$str; }); /* Custom exception handler */ set_exception_handler(function($exception) { echo ‘Uncaught exception: ‘.$exception->getMessage(); }); ?> Wednesday, February 27, 2013
28. Planning for the Future Wednesday, February 27, 2013
29. Developer Training Wednesday, February 27, 2013
30. Code Evaluation Wednesday, February 27, 2013
31. Secure Coding Standard Wednesday, February 27, 2013
32. Fixing secure development takes more than just knowing the problems. Wednesday, February 27, 2013
33. Thanks! @enygma http://websec.io https://joind.in/7911 Wednesday, February 27, 2013