This indicates an attack attempt to exploit an Integer Overflow Vulnerability in Adobe Systems Acrobat XI.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted file. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted file.
Adobe Systems Acrobat 2017 2017.011.30066 and earlier versions
Adobe Systems Acrobat DC (Classic) 2015.006.30355 and earlier
Adobe Systems Acrobat DC (Continuous) 2017.012.20098 and earlier
Adobe Systems Acrobat XI 11.0.22 and earlier
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor: