After attending Drupal HackCamp 2018 in Bucharest, an event focused on security with international speakers, I gained valuable insights about web security that I'd like to share. The conference reinforced that security isn't just a backend concern - it requires vigilance from all developers across the technology stack.

SQL Injection Prevention

One of the most critical security vulnerabilities in web applications is SQL injection. Consider this vulnerable query:

// UNSAFE: Direct variable interpolation in SQL query
$result = db_query("SELECT n.title FROM {node} n WHERE n.type = '$type'");

This code is susceptible to SQL injection attacks. A malicious user could inject a UNION query like:

story' UNION SELECT s.sid, s.sid FROM {sessions} s WHERE s.uid = 1 --

This injection could expose sensitive data, including administrative session information. Here's how to write secure queries instead:

// SAFE: Using parameterized queries with proper escaping
$result = db_query("SELECT n.nid FROM {node} n WHERE n.nid > :nid", 
 array(':nid' => $nid)
);
// Alternative using the Database API
$query = db_select('node', 'n')
 ->fields('n', array('nid'))
 ->condition('n.nid', $nid, '>')
 ->execute();

Output Sanitization

JavaScript Security
To prevent XSS attacks in JavaScript, always sanitize data before inserting it into the DOM:

// SAFE: Sanitize text before DOM insertion
var safeText = Drupal.checkPlain(userProvidedText);
element.innerHTML = safeText;

Translation Security
Drupal's translation system provides multiple placeholder types for different security contexts:

// Different placeholder types for different security needs
$text = t('Welcome @user to %site_name. Visit :link', array(
 '@user' => $username,        // Plain text replacement
 '%site_name' => $siteName,   // Text wrapped in <em> tags
 ':link' => $url,             // URL for href attributes
));

String Sanitization Methods
Drupal provides several methods for securing output:

// Escape HTML special characters
$safeText = Html::escape($userInput);
// Format strings with placeholders safely
use Drupal\Component\Render\FormattableMarkup;
$safeMarkup = new FormattableMarkup($pattern, $arguments);
// Filter HTML to prevent XSS
$safeHtml = Xss::filter($userGeneratedHtml);

Security Best Practices

1. Regular Updates
  - Subscribe to security announcements via email/RSS/Twitter
  - Keep Drupal core and contributed modules updated
  - Implement automated update notifications

2. Development Environment Security

  // Check if we're in a production environment
  if (getenv('ENVIRONMENT') === 'production') {
    // Disable development modules
    module_disable(array('devel', 'simpletest'));
    // Remove Composer dev dependencies
    shell_exec('composer install --no-dev');
  }

3. Testing Module Security

  // Only enable testing modules in development
  if (!drupal_is_cli() && !in_array('testing', variable_get('enabled_modules', array()))) {
    module_disable(array('simpletest'));
  }

The conference reinforced that security is a shared responsibility requiring constant vigilance and updated knowledge. By implementing these practices consistently, we can create more secure Drupal applications that better protect our users and their data.

Remember: Security is not a one-time implementation but an ongoing process requiring regular audits, updates, and improvements to stay ahead of emerging threats.