diff --git a/ajax.php b/ajax.php
index b4a02ce71..2fa9f7a73 100644
--- a/ajax.php
+++ b/ajax.php
@@ -106,6 +106,31 @@
     die();
 }
 
+$installerActive = (!file_exists('INSTALL_BLOCK'));
+if ($installerActive)
+{
+    $module = '';
+    if (strpos($_REQUEST['f'], ':') !== false)
+    {
+        $parameters = explode(':', $_REQUEST['f']);
+        $module = preg_replace("/[^A-Za-z0-9]/", "", $parameters[0]);
+    }
+
+    if ($module !== 'install')
+    {
+        header('Content-type: text/xml');
+        echo '<?xml version="1.0" encoding="', AJAX_ENCODING, '"?>', "\n";
+        echo(
+            "<data>\n" .
+            "    <errorcode>-1</errorcode>\n" .
+            "    <errormessage>Installer is active. Only installer AJAX actions are allowed.</errormessage>\n" .
+            "</data>\n"
+        );
+
+        die();
+    }
+}
+
 if (strpos($_REQUEST['f'], ':') === false)
 {
     $function = preg_replace("/[^A-Za-z0-9]/", "", $_REQUEST['f']);
diff --git a/modules/install/ajax/ui.php b/modules/install/ajax/ui.php
index 27b07ef3d..cc601d92f 100755
--- a/modules/install/ajax/ui.php
+++ b/modules/install/ajax/ui.php
@@ -124,22 +124,22 @@
         {
             if (isset($_REQUEST['user']) && !empty($_REQUEST['user']))
             {
-                CATSUtility::changeConfigSetting('DATABASE_USER', "'" . $_REQUEST['user'] . "'");
+                CATSUtility::changeConfigSetting('DATABASE_USER', var_export($_REQUEST['user'], true));
             }
 
             if (isset($_REQUEST['pass']) && $_REQUEST['pass'] !== '')
             {
-                CATSUtility::changeConfigSetting('DATABASE_PASS', "'" . $_REQUEST['pass'] . "'");
+                CATSUtility::changeConfigSetting('DATABASE_PASS', var_export($_REQUEST['pass'], true));
             }
 
             if (isset($_REQUEST['host']) && !empty($_REQUEST['host']))
             {
-                CATSUtility::changeConfigSetting('DATABASE_HOST', "'" . $_REQUEST['host'] . "'");
+                CATSUtility::changeConfigSetting('DATABASE_HOST', var_export($_REQUEST['host'], true));
             }
 
             if (isset($_REQUEST['name']) && !empty($_REQUEST['name']))
             {
-                CATSUtility::changeConfigSetting('DATABASE_NAME', "'" . $_REQUEST['name'] . "'");
+                CATSUtility::changeConfigSetting('DATABASE_NAME', var_export($_REQUEST['name'], true));
             }
 
             echo '
@@ -244,11 +244,11 @@
                 CATSUtility::changeConfigSetting('MAIL_SMTP_AUTH', 'false');
             }
 
-            CATSUtility::changeConfigSetting('MAIL_SENDMAIL_PATH', '"' . $mailSendmailPath . '"');
-            CATSUtility::changeConfigSetting('MAIL_SMTP_HOST', '"' . $mailSmtpHost . '"');
+            CATSUtility::changeConfigSetting('MAIL_SENDMAIL_PATH', var_export($mailSendmailPath, true));
+            CATSUtility::changeConfigSetting('MAIL_SMTP_HOST', var_export($mailSmtpHost, true));
             CATSUtility::changeConfigSetting('MAIL_SMTP_PORT', sprintf('%d', $mailSmtpPort));
-            CATSUtility::changeConfigSetting('MAIL_SMTP_USER', '"' . $mailSmtpUsername . '"');
-            CATSUtility::changeConfigSetting('MAIL_SMTP_PASS', '"' . $mailSmtpPassword . '"');
+            CATSUtility::changeConfigSetting('MAIL_SMTP_USER', var_export($mailSmtpUsername, true));
+            CATSUtility::changeConfigSetting('MAIL_SMTP_PASS', var_export($mailSmtpPassword, true));
 
             @session_name(CATS_SESSION_NAME);
             session_start();
@@ -420,20 +420,16 @@
             </script>';
 
         $antiwordPath = $_REQUEST['docExecutable'];
-        $antiwordWithSlashes = str_replace('\\', '\\\\', $antiwordPath);
-        CATSUtility::changeConfigSetting('ANTIWORD_PATH', '"' . $antiwordWithSlashes . '"');
+        CATSUtility::changeConfigSetting('ANTIWORD_PATH', var_export($antiwordPath, true));
 
         $pdftotextPath = $_REQUEST['pdfExecutable'];
-        $pdftotextWithSlashes = str_replace('\\', '\\\\', $pdftotextPath);
-        CATSUtility::changeConfigSetting('PDFTOTEXT_PATH', '"' . $pdftotextWithSlashes . '"');
+        CATSUtility::changeConfigSetting('PDFTOTEXT_PATH', var_export($pdftotextPath, true));
 
         $html2textPath = $_REQUEST['htmlExecutable'];
-        $html2textWithSlashes = str_replace('\\', '\\\\', $html2textPath);
-        CATSUtility::changeConfigSetting('HTML2TEXT_PATH', '"' . $html2textWithSlashes . '"');
+        CATSUtility::changeConfigSetting('HTML2TEXT_PATH', var_export($html2textPath, true));
 
         $unrtfPath = $_REQUEST['rtfExecutable'];
-        $unrtfWithSlashes = str_replace('\\', '\\\\', $unrtfPath);
-        CATSUtility::changeConfigSetting('UNRTF_PATH', '"' . $unrtfWithSlashes . '"');
+        CATSUtility::changeConfigSetting('UNRTF_PATH', var_export($unrtfPath, true));
 
         break;