This indicates an attack attempt against a Denial of Service vulnerability in Advantech WebAccess.
The vulnerability is caused by an error when the vulnerable software handles an out of bound memory access. This vulnerability allows attackers to cause a denial of service on vulnerable installations of the software.
Advantech WebAccess 8.1 and 7.2
Denial of Service: Remote attackers can crash vulnerable systems.
Apply the most recent upgrade or patch from the vendor.