This indicates an attack attempt to exploit an Authentication Bypass vulnerability in Beckhoff IPC Diagnostics.
A remote unauthenticated attacker could exploit this vulnerability by sending a crafted HTTP request to the vulnerable server. An attacker can exploit this to add new user with administrator privileges in the affected system.
Beckhoff IPC Diagnostics prior to 1.8
Security Bypass: Remote attackers can bypass security features of vulnerable systems without authentication.
Currently we are unaware of any vendor supplied patch or updates available for this issue.