This malware category is related to malicious code hidden inside of the the server configuration file .htaccess For example, additional handler can be found in such infected .htaccess file which enables processing of various non-standard file extensions as cgi script. Files with these extensions could be e.g. tools for hacking cPanel written in various scripting languages such as Python or Perl
Any Apache based web server hosting vulnerable software or with compromised credentials.
Review your .htaccess rules and remove any RewriteRule that you do not recognize