[Mimedefang] patch to add blocking of encrypted email via uv scan

[Matthew.van.Eerde at hbinc.com]

Nonetheless, I personally live in fear of the day some virus writer includes
a built-in zip engine in their virus - which at every run generates a random
password, encrypts itself, and sends its encrypted version to every email it
can find.

That will be the day I block encrypted .zip files.

Matt
 
> If the same password, or a small set of passwords are used with the
> virus, then the resulting encrypted file is constant (or a small set
> of constant files), and so the virus scanner will still have patterns
> to search for.  Or, it could decrypt the file and search for a single
> pattern, presumably whichever is more efficient.
> 
> Mike