This indicates an attack attempt against a code-execution vulnerability in Adobe Acrobat Reader.
The vulnerability is caused by an error when the vulnerable software handles a crafted .pdf file. It allows a remote attacker to execute arbitrary code via sending a crafted .pdf file.
Adobe Reader and Acrobat 8.1.2 and earlier
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the patch, available from the following web site: