This indicates an attack attempt against an Authentication Bypass vulnerability in the web interface of Trihedral VTScada.
The vulnerability is due to insufficient input validation in the application when handling a crafted request. A remote attacker may be able to to access confidential information via a crafted request, under the context of the user running the service.
Trihedral VTScada v8.0 through 11.2.01
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the latest update from the vendor.