This indicates an attack attempt against an Information Disclosure vulnerability in Microsoft Internet Explorer.
The vulnerability is caused by an error when the vulnerable software handles a specially crafted HTML file. A remote attacker can exploit this to gain unauthorized access to sensitive information.
Internet Explorer 8
Internet Explorer 9
Internet Explorer 10
Internet Explorer 11
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor.