SUPEE-6788 variable + block setup script. 1.) Create a new module or extend a current one. 2.) Create a new install or setup script with the variables and blocks which are not whitelisted yet.

data-upgrade-0.1.67-0.1.68.php

<?php
/**
 * @category  Namespace
 * @package   Namespace_Module
 * @author    Anna Völkl
 * @author    Christoph Aßmann
 * @author    Fabian Schmengler
 */

/** @var Mage_Core_Model_Resource_Setup $installer */
$installer = $this;

// Make sure the upgrade is not performed on legacy installations with tables missing
$adminVersion = Mage::getConfig()->getModuleConfig('Mage_Admin')->version;
if (version_compare($adminVersion, '1.6.1.1', '>')) {

    $connection = $installer->getConnection();

    //---------------------------------------------------
    // Add variables
    //---------------------------------------------------
    $table = $installer->getTable('admin/permission_variable');
    $variableNames = array(
        'design/email/logo_alt',
        'design/email/logo_width',
        'design/email/logo_height',
    );
    foreach ($variableNames as $variableName) {
        $connection->insertIgnore($table, array(
            'variable_name' => $variableName,
            'is_allowed' => 1,
        ));
    }

    //---------------------------------------------------
    // Add blocks
    //---------------------------------------------------
    $table = $installer->getTable('admin/permission_block');
    $blockNames = array(
        'cms/block',
        'catalog/product_list',
        'germany/impressum',
        'page/html',
        'magesetup/imprint_field',
        'magesetup/imprint_content'
    );
    foreach ($blockNames as $blockName) {
        $connection->insertIgnore($table, array(
            'block_name' => $blockName,
            'is_allowed' => 1,
        ));
    }

}