This indicates an attack attempt against a remote code execution vulnerability in Macro Express Pro.
The vulnerability is caused by an error when the vulnerable software handles a specially crafted MXE file. It allows a remote attacker to execute arbitrary code.
Insight Software Solutions Macro Express Pro 4.2.1 1
Insight Software Solutions Macro Express 3
System Compromise: Remote attackers can gain control of vulnerable systems.
Currently we are not aware of any patches supplied by the vendor for this issue.