diff --git a/app/Helpers/Attachments/AttachmentHelper.php b/app/Helpers/Attachments/AttachmentHelper.php
index cbb6656967..375f5ec915 100644
--- a/app/Helpers/Attachments/AttachmentHelper.php
+++ b/app/Helpers/Attachments/AttachmentHelper.php
@@ -59,7 +59,7 @@ class AttachmentHelper implements AttachmentHelperInterface
      */
     public function getAttachmentLocation(Attachment $attachment): string
     {
-        $path = sprintf('%s%sat-%d.data', storage_path('upload'), DIRECTORY_SEPARATOR, $attachment->id);
+        $path = sprintf('%s%sat-%d.data', storage_path('upload'), DIRECTORY_SEPARATOR, intval($attachment->id));
 
         return $path;
     }
diff --git a/app/Http/Controllers/ImportController.php b/app/Http/Controllers/ImportController.php
index 7024bf46b8..877c9ab084 100644
--- a/app/Http/Controllers/ImportController.php
+++ b/app/Http/Controllers/ImportController.php
@@ -416,17 +416,24 @@ class ImportController extends Controller
      * @param ImportJob $job
      *
      * @return SetupInterface
+     * @throws FireflyException
      */
     private function makeImporter(ImportJob $job): SetupInterface
     {
         // create proper importer (depends on job)
-        $type = $job->file_type;
+        $type = strtolower($job->file_type);
 
-        /** @var SetupInterface $importer */
-        $importer = app('FireflyIII\Import\Setup\\' . ucfirst($type) . 'Setup');
-        $importer->setJob($job);
+        // validate type:
+        $validTypes = array_keys('firefly.import_formats');
 
-        return $importer;
+        if (in_array($type, $validTypes)) {
+            /** @var SetupInterface $importer */
+            $importer = app('FireflyIII\Import\Setup\\' . ucfirst($type) . 'Setup');
+            $importer->setJob($job);
+
+            return $importer;
+        }
+        throw new FireflyException(sprintf('"%s" is not a valid file type', $type));
 
     }
 
diff --git a/app/Import/Importer/CsvImporter.php b/app/Import/Importer/CsvImporter.php
index e377b9baa7..f356c25e47 100644
--- a/app/Import/Importer/CsvImporter.php
+++ b/app/Import/Importer/CsvImporter.php
@@ -11,6 +11,7 @@ declare(strict_types = 1);
 
 namespace FireflyIII\Import\Importer;
 
+use FireflyIII\Exceptions\FireflyException;
 use FireflyIII\Import\Converter\ConverterInterface;
 use FireflyIII\Import\ImportEntry;
 use FireflyIII\Import\Specifics\SpecificInterface;
@@ -120,8 +121,14 @@ class CsvImporter implements ImporterInterface
 
         foreach ($row as $rowIndex => $value) {
             // find the role for this column:
-            $role           = $config['column-roles'][$rowIndex] ?? '_ignore';
-            $doMap          = $config['column-do-mapping'][$rowIndex] ?? false;
+            $role            = $config['column-roles'][$rowIndex] ?? '_ignore';
+            $doMap           = $config['column-do-mapping'][$rowIndex] ?? false;
+            $validConverters = array_keys('csv.import_roles');
+
+            // throw error when not a valid converter.
+            if (!in_array($role, $validConverters)) {
+                throw new FireflyException(sprintf('"%s" is not a valid role.', $role));
+            }
             $converterClass = config('csv.import_roles.' . $role . '.converter');
             $mapping        = $config['column-mapping-config'][$rowIndex] ?? [];
             $className      = sprintf('FireflyIII\\Import\\Converter\\%s', $converterClass);
diff --git a/app/Import/Setup/CsvSetup.php b/app/Import/Setup/CsvSetup.php
index e5f6e6ca6f..50b5d1274b 100644
--- a/app/Import/Setup/CsvSetup.php
+++ b/app/Import/Setup/CsvSetup.php
@@ -14,6 +14,7 @@ namespace FireflyIII\Import\Setup;
 
 use ExpandedForm;
 use FireflyIII\Crud\Account\AccountCrud;
+use FireflyIII\Exceptions\FireflyException;
 use FireflyIII\Import\Mapper\MapperInterface;
 use FireflyIII\Import\MapperPreProcess\PreProcessorInterface;
 use FireflyIII\Import\Specifics\SpecificInterface;
@@ -326,6 +327,7 @@ class CsvSetup implements SetupInterface
 
     /**
      * @return array
+     * @throws FireflyException
      */
     private function getDataForColumnMapping(): array
     {
@@ -335,11 +337,19 @@ class CsvSetup implements SetupInterface
 
         foreach ($config['column-do-mapping'] as $index => $mustBeMapped) {
             if ($mustBeMapped) {
-                $column        = $config['column-roles'][$index] ?? '_ignore';
+                $column = $config['column-roles'][$index] ?? '_ignore';
+
+                // is valid column?
+                $validColumns = array_keys(config('csv.import_roles'));
+                if (!in_array($column, $validColumns)) {
+                    throw new FireflyException(sprintf('"%s" is not a valid column.', $column));
+                }
+
                 $canBeMapped   = config('csv.import_roles.' . $column . '.mappable');
                 $preProcessMap = config('csv.import_roles.' . $column . '.pre-process-map');
                 if ($canBeMapped) {
-                    $mapperName = '\FireflyIII\Import\Mapper\\' . config('csv.import_roles.' . $column . '.mapper');
+                    $mapperClass = config('csv.import_roles.' . $column . '.mapper');
+                    $mapperName  = sprintf('\\FireflyIII\\Import\Mapper\\%s', $mapperClass);
                     /** @var MapperInterface $mapper */
                     $mapper       = new $mapperName;
                     $indexes[]    = $index;
@@ -352,8 +362,11 @@ class CsvSetup implements SetupInterface
                         'values'        => [],
                     ];
                     if ($preProcessMap) {
-                        $data[$index]['preProcessMap'] = '\FireflyIII\Import\MapperPreProcess\\' .
-                                                         config('csv.import_roles.' . $column . '.pre-process-mapper');
+                        $preClass                      = sprintf(
+                            '\\FireflyIII\\Import\\MapperPreProcess\\%s',
+                            config('csv.import_roles.' . $column . '.pre-process-mapper')
+                        );
+                        $data[$index]['preProcessMap'] = $preClass;
                     }
                 }
 
@@ -365,15 +378,21 @@ class CsvSetup implements SetupInterface
         /** @var Reader $reader */
         $reader = Reader::createFromString($content);
         $reader->setDelimiter($config['delimiter']);
-        $results = $reader->fetch();
+        $results        = $reader->fetch();
+        $validSpecifics = array_keys('csv.import_specifics');
 
         foreach ($results as $rowIndex => $row) {
 
             // run specifics here:
             // and this is the point where the specifix go to work.
             foreach ($config['specifics'] as $name => $enabled) {
+
+                if (!in_array($name, $validSpecifics)) {
+                    throw new FireflyException(sprintf('"%s" is not a valid class name', $name));
+                }
+                $class = config('csv.import_specifics.' . $name);
                 /** @var SpecificInterface $specific */
-                $specific = app('FireflyIII\Import\Specifics\\' . $name);
+                $specific = app($class);
 
                 // it returns the row, possibly modified:
                 $row = $specific->run($row);