Hello sir , as an administrator System/Networking related to iT security , i would give you some advices before we proceed , your server is mainly attacked from hackers using random exploits , i suggest that you upgrade the Joomla version to it's highest or we can proceed with the Code analysis to find the Backdoor , i will scan your website from outside i would need your permission of course as an ethical hacker , and once the bug found we will close it , secure it and then Upload it back before they extract your database and sell it with a cheap price on darknet or manipulate your data . feel free to contact me for further questions i'm available. Thank you
AYOUB ERRAZKI