This indicates an attempt to exploit an input validation error in Adobe Acrobat and Adobe Reader.
There is a vulnerability in Adobe Acrobat and Adobe Reader which can be exploited by attackers to execute arbitrary commands on an affected system with Internet Explorer 7 installed. This issue is caused by an input validation error when processing a specially crafted "mailto:" link contained in a PDF file.
Adobe Reader version 8.1 and prior
Adobe Acrobat Standard version 8.1 and prior
Adobe Acrobat Professional version 8.1 and prior
Adobe Acrobat Elements version 8.1 and prior
Adobe Acrobat 3D
System compromise: Arbitrary code execution.
No update available. The workaround is to disable the "mailto:" option in the Windows registry :