Hmm, hike I underestimated my work. Docker set up until 2 am. And then in the morning I spent another 3 hours. I looked at the source code – most likely, viruses were still uploaded to the site, since it has not been updated for a long time. At least judging by the code, the backdoor blanks are loaded there. Time 12-47. Now I will test updating the site to the latest version of Drupal 7.81 with a relatively new version of PHP. Anyone who does not understand what I am writing is okay. Over time, I will try to get rid of these wild words, but sometimes I just need to show and, at least for myself, leave notes on the difficulties I face.
By the end of the day, an error occurred on the main project – the user could not upload documents for verification. I immediately requested additional information on the uploaded documents, but apart from that I considered 4 upload options and all worked as expected. As I expected, the error was a special case and was associated with exceeding the size of the downloaded files. I significantly increased these settings both on the server and in the site code and everything worked.
In the evening, the support service changed the PHP version and at night I finally completed the project update and removed all viruses.
Walk: 5 km; Push-ups: 10; Squats: 10.