Well, encrypting, packaging ... whatever, most of what Viper is doing is getting something across that is probably going through a default desktop version of NAV. NAV can be tweaked to look deeper into things, like Zip files and such.
Once that file gets decrypted or unpackaged, NAV, McAfee or any other will nail it. Looking that deep into an encrypted file will take time. On an enterprise level, we can't afford to take that kind of time. We just delete or quarrantine files that cannot be scanned or are encrypted.
Makes some folks a bit testy when something they think is fine gets nailed in the quarrantine. But, my network doesn't get nailed.