This indicates an attack attempt against a Information Disclosure vulnerability in Advantech/BroadWin WebAccess.
The vulnerability is caused by an error when the vulnerable software handles the malicious http request. It allows a remote attacker to gain sensitive information via a crafted HTTP request.
Advantech/BroadWin WebAccess 7.0
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue.