This indicates an attack attempt to exploit a Directory Traversal vulnerability in Advantech WebAccess.
The vulnerability is caused by improper validation of user supplied data when the vulnerable application handles a maliciously crafted request. An attacker can exploit this to manipulate files on the affected machine via a crafted request. Also a remote attacker may use it to cause denial of service condition in the affected machine via a crafted request
Advantech WebAccess 8.0 and prior
Denial of Service: Remote attackers can crash vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue