This indicates an attack attempt to exploit an Information Disclosure vulnerability in Microsoft Internet Explorer and Edge.
The vulnerability is due to an error when the vulnerable software attempts to handle a maliciously crafted SWF file. An attacker can exploit this by tricking a user into visiting a malicious SWF file and gain sensitive information from vulnerable systems.
Internet Explorer 9
Internet Explorer 10
Internet Explorer 11
Internet Explorer 11 on Windows 10
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor