This indicates an attack attempt against a zero-day Code Execution vulnerability in Adobe Reader and Acrobat.
The vulnerability is caused by an error when the vulnerable software handles a specially crafted PDF file that could allow remote attackers to execute arbitrary code.
Adobe Reader 9.2 and earlier versions
Adobe Acrobat 9.2 and earlier versions
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the patch supplied by the vendor: