This indicates an attack attempt to exploit a Memory Corruption vulnerability in Adobe Illustrator.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted AI file. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted AI file.
Adobe Illustrator CS5.5 (15.1) and earlier for Windows and Macintosh
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.