"SEP not detecting a packaged malware application

HI ,

During one of the pentesting results Symantec wasnt able to detect a malware called injector.exe when it was packaged.

I understand that symantec detects the malware based on the filefingerprint and that when it was packaged the fingerprint changed and hence wasnt detected .....

but if above is the case ... whats the solution for this .

How can we stop malware and virus when they are packaged .

blocking the malware through filefinger print would be a solution but then how many malwares can be block in tht way .......