This indicates an attack attempt to exploit a remote Code Execution vulnerability in Adobe Acrobat and Reader.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted PDF file. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted PDF file.
Adobe Reader XI (11.0.01 and earlier) for Windows and Macintosh
Adobe Reader X (10.1.5 and earlier) for Windows and Macintosh
Adobe Reader 9.5.3 and earlier 9.x versions for Windows, Macintosh and Linux
Adobe Acrobat XI (11.0.01 and earlier) for Windows and Macintosh
Adobe Acrobat X (10.1.5 and earlier) for Windows and Macintosh
Adobe Acrobat 9.5.3 and earlier 9.x versions for Windows and Macintosh
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.