Trojan?

It is possible that a malware installed itself to that location but could really come from anywhere. Could you install something like Wordfence on your site and do a scan with it?
https://www.ads-software.com/plugins/wordfence/

As you can see the folder in the plugin is clean:
https://plugins.svn.www.ads-software.com/synved-shortcodes/trunk/synved-option/addons/option-type-addon/script/

Yes, I think is was a malware, there were two more files in that folder – 404.php and main.php.

Thanks