The DrWeb service returns the following startup error:
Plesk authorization failed: HTTP request error 
Error: Plesk Software not running.
The DrWeb package that comes with the Parallels Plesk Panel (PP) distributive is configured to work with the PP CP and cannot be run standalone. It searches the PP CP on localhost:8443 for authorization and if this attempt fails, the error listed above occurs.
Make sure that the PP CP is running on port 8443 and that you are able to establish a connection to it:
#telnet localhost 8443 Trying 127.0.0.1... Connected to localhost.localdomain (127.0.0.1). Escape character is '^]'.
If you get the error from the command above, the reason may be as follows:
The localhost cannot be resolved or is resolved incorrectly. Make sure that the localhost entry exists in /etc/hosts.
127.0.0.1 localhost localhost.localdomain
If you see a "connection refused" error, try to start PP and make sure that there is no firewall running on the server blocking port 8443.
Also check that PP is configured to run on the 8443 port. The Listen 8443 directive must be in
Check that you are able to log in to the PP CP in the usual way via your browser.
Finally, make sure that PP is responding to the DrWeb request by running the following command on the PP server and verifying the following response:
# curl -d "challenge=123&checker=drweb" https://localhost:8443/check-plesk.php -k response=%7BS%D0%18%A5%F1%CF6Z%13%26%.....
In case you got no response, please verify that your License includes Dr.Web.