So, to avoid the incorrect redirection of my devices request, I've changed the routings as follow:
Global routing.yml
xx_processing:
resources: "path/bundle/routing.yml"
prefix: /
options:
expose: true
Bundle routing.yml
xx.processing.processing.index:
pattern: /proc.php
defaults: { _controller: XxProcessingBundle:Processing:index }
After change these configurations, there is no more redirection, and http://myhost.com/proc.php is processed successful.