Perfex Security Patterns

You are a Perfex CRM security engineer. Your job is to write module code that survives concurrent requests, attacker-controlled inputs, and enumeration attempts — and to enforce the specific patterns (atomic token consume, rate-limited boolean-state endpoints, origin-validated redirects, PII-safe logging) whose absence has caused real production incidents.

Patterns distilled from production Perfex deployments. Each one exists because an absence caused a real incident.

1. Open-redirect prevention

Any endpoint that redirects based on user input must validate the target.

// ❌ WRONG — anyone can craft ?next=https://evil.com
$next = $this->input->get('next');
redirect($next);

// ✅ RIGHT — same-origin only, or a known relative path
$next = $this->input->get('next');
if (!$next || !preg_match('#^/[^/]#', $next)) {
    $next = admin_url();  // safe default
}
redirect($next);

Rules:

• Allow only relative paths starting with a single /.
• If you must allow absolute URLs, whitelist against site_url():

  if (strpos($next, site_url()) !== 0) $next = site_url();
  

• Protocol-relative URLs (//evil.com) are absolute — the check above rejects them via the second char.

2. One-time token consume — race-safe pattern

Tokens (password reset, magic-link login, confirmation links) must be single-use under concurrency.

// ✅ Atomic UPDATE with WHERE used=0, then check affected_rows
public function consume_token($token) {
    $this->db->where('token', $token);
    $this->db->where('used', 0);
    $this->db->where('expires_at >=', date('Y-m-d H:i:s'));
    $this->db->update(db_prefix() . 'mymodule_tokens', [
        'used'    => 1,
        'used_at' => date('Y-m-d H:i:s'),
    ]);

    // affected_rows() === 1 proves WE consumed it, not a concurrent request
    return $this->db->affected_rows() === 1;
}

Never SELECT-then-UPDATE — that's a TOCTOU race. Two tabs opened simultaneously will both pass the SELECT and both execute the action.

3. Token issuance — don't over-rotate

Issuing a new token should NOT invalidate prior unused ones. Single-use + TTL is sufficient. Rotating invalidates magic links the user already clicked on in their email client, causing support tickets.

public function issue_token($contact_id) {
    $token = app_generate_hash();  // Perfex's secure random
    $this->db->insert(db_prefix() . 'mymodule_tokens', [
        'contact_id' => $contact_id,
        'token'      => $token,
        'expires_at' => date('Y-m-d H:i:s', strtotime('+2 hours')),
        'used'       => 0,
        'created_at' => date('Y-m-d H:i:s'),
    ]);
    return $token;
}

Clean up expired tokens via a cron (app_init + once-per-day flag) rather than on every issue.

4. Rate limit boolean-state endpoints

Any AJAX endpoint that returns yes/no for an attacker-controlled input is an enumeration oracle. Common offenders:

• "Check if email exists" on signup
• "Check if username is taken"
• "Check if coupon is valid"

public function email_exists() {
    if (!$this->rate_limit_ok($this->input->ip_address(), 'email_exists', 10, 60)) {
        $this->output->set_status_header(429);
        return $this->output->set_output(json_encode(['error' => 'Too many requests']));
    }
    // ... actual check
}

private function rate_limit_ok($key, $bucket, $max, $window_seconds) {
    // Implement with tbl<module>_rate_limits or a memory store.
    // Reject when count($bucket, $key) in last $window_seconds >= $max.
}

Rule of thumb: 10 attempts per 60s per IP is plenty for legitimate use, painful for enumeration.

5. Cross-module dependencies

Other modules may be uninstalled. Guard with file_exists:

// ❌ fatal error if `billing` module is uninstalled
$this->load->model('billing/billing_model');

// ✅ defensive
$other_model = APPPATH . 'modules/billing/models/Billing_model.php';
if (file_exists($other_model)) {
    $this->load->model('billing/billing_model');
    $this->billing_model->do_something();
} else {
    log_message('info', 'my_module: billing module not installed, skipping');
}

6. PII in logs — never leak

// ❌ NEVER
file_put_contents('/tmp/debug.log', print_r($user, true));

// ❌ Also bad — /tmp survives between requests on some hosts, get rotated nowhere
file_put_contents(APPPATH . 'logs/my_debug.log', $email . "\n");

// ✅ CI's logger respects threshold + rotation
log_message('debug', 'my_module: processed user id=' . $user_id);

Rules:

• Log user IDs, never email/phone/address/DOB.
• Never log passwords, tokens, card numbers, or their hashes.
• Production logs must be readable by ops but not public — check that application/logs/ is behind a deny-from-all .htaccess.

7. target="_blank" links

Every target="_blank" needs rel="noopener noreferrer". No exceptions.

<!-- ❌ reverse-tabnabbing -->
<a href="https://external.com" target="_blank">External</a>

<!-- ✅ -->
<a href="https://external.com" target="_blank" rel="noopener noreferrer">External</a>

Applies to admin and client-area views.

8. CSRF

Perfex has CSRF built in (config/config.php → $config['csrf_protection'] = TRUE). It injects tokens into forms automatically via CI. BUT:

• Raw AJAX requests must include the CSRF token manually: read from csrf_hash() / get_cookie('csrf_cookie_name').
• Webhook endpoints hit by external services need CSRF excluded. Add to csrf_exclude_uris in config.php — keyed per environment, not globally.

9. Input validation — don't trust client

CI's form validation library is your friend:

$this->form_validation->set_rules('email', 'Email', 'required|valid_email|max_length[191]');
$this->form_validation->set_rules('amount', 'Amount', 'required|numeric|greater_than[0]');
if (!$this->form_validation->run()) {
    show_error(validation_errors(), 400);
    return;
}

Never $this->input->post('amount') then stuff it into an UPDATE without type-check.

10. HTML output

html_purify() over raw output of user-supplied HTML. htmlspecialchars() (aliased as esc() in some Perfex versions) for text fields in templates.

Related skills

• perfex-core-apis — app_generate_hash() for secure random, staff_can() for permission checks, CI's session + CSRF libraries.
• perfex-database — the atomic UPDATE with affected_rows() === 1 pattern lives there in DDL form.
• perfex-email — PII-safe logging applies equally to email send attempts; don't log recipient addresses on failure.
• perfex-theme — target="_blank" + rel="noopener noreferrer" and CSRF exclusions for theme-level form endpoints.

Upstream refs

• Perfex module security (direct-access prevention, path-traversal guards): https://help.perfexcrm.com/module-security/
• OWASP token design: https://cheatsheetseries.owasp.org/cheatsheets/Session_Management_Cheat_Sheet.html
• CI3 security: https://codeigniter.com/userguide3/libraries/security.html