Hm, either this question is more suitable for StackExchange or some similar forum, I’ll try to provide the solution.
Consider moving content of the hacksleak.in which is in your DocumentRoot /htdocs/ to /htdocs/hacksleak/ and apply the change in the httpd-vhosts.conf file too.
Open your httpd.conf file and look for
#NameVirtualHost *:80
Uncomment it.
Change the value for ErrorLog and CustomLog based on your requirement (why are you using the same log for both domains?)
And you are using HTTP 80 port, while I can access your websites over HTTPS → May I ask if you are using the Flexible SSL option under the SSL/TLS tab of Cloudflare dashboard for your domain name?
Kindly, I’d suggest you to check your .htaccess file for your sub-domain decrypt and also php.ini just in case.
→ you are also running old PHP version …
That 403 error is coming from your origin host/server.
Nevertheless, check access and error log files for any clue due to troubleshooting.
CHMOD set to 755? Try 775 for testing purpose.
If so, but how about user/group ownership of htdocs and sub-directories including the .html/.php files inside?
Per default, not quite exactly due to Group Policies and other stuff (you are running XAMPP instead of the IIS due to the lack of support for PHP/MySQL).
Unfortunately, it’s an off-topic for this forums either, but I am trying to help to give you any suggestions what and where to troubleshoot something and also which is not anymore related to Cloudflare.