Hello Milan Köhler,
Thank you for using the Sandfly Support forums regarding the process_running_hidden_proc_dir_writable sandfly.
That Sandfly was added in version 4.6.1, however, it has since been completely removed in future versions of Sandfly due to producing false positives. We advise you to disable that sandfly (along with process_running_hidden_proc_dir_spoofing_2) until Sandfly can be upgraded.
Please see the Activating and Deactivating Sandflies documentation for details on how to do that.
Sincerely,
Sandfly Security Customer Service
Thanks
Milan Köhler