This indicates an attack attempt against a heap-overflow vulnerability in Adobe products.
The vulnerability is caused by an error when the vulnerable software handles malformed PDF files. A remote attacker may exploit this to execute arbitrary code via a crafted PDF file.
Adobe Reader 9.3.4 and earlier versions for Windows, Macintosh and UNIX
Adobe Acrobat 9.3.4 and earlier versions for Windows and Macintosh
System Compromise: Remote attackers can gain control of vulnerable systems.
Refer to the following Adobe advisory for the updates: