This indicates an attack attempt to exploit a Denial of Service Vulnerability in Advantech WebAccess.
A remote, unauthenticated attacker could exploit this vulnerability by sending a maliciously crafted RPC request to the target server. Successful exploitation could result in WebAccess being uninstalled and denial-of-service condition.
Advantech WebAccess 8.3.5 and prior
Denial of Service: Remote attackers can crash vulnerable systems.
Upgrade to the latest version available from the website.