Is it 100% manageable? If the malware author manages to infiltrate your network and quietly starts infecting files and devices on your network over 6 months, e

Is it 100% manageable? If the malware author manages to infiltrate your network and quietly starts infecting files and devices on your network over 6 months, even if you restore from a 7 month old backup, what about all of the files that were created between then and now -- are they all going to be recoverable even if you can find and remove the malware? Can you reliably detect all of the malware or will the attack sprout again from your printer in a few months?