topic Re: Encrypted and Zipped files with virus in it in General Topics

Encrypted and Zipped files with virus in it

scantwell — Wed, 06 Mar 2013 15:44:38 GMT

So I have a nice easy question. If we have a file that is both encrypted and zipped (like with a .zipx extension from WinZip) can the firewall determine through its signatures that the file has a virus, or would it send it up to Wildfire? Thanks

Re: Encrypted and Zipped files with virus in it

zarina — Wed, 06 Mar 2013 17:49:55 GMT

To look inside the encrypted file, you will need to have a decryption policy in place.We do look inside the zip file to determine if its malicious.

Re: Encrypted and Zipped files with virus in it

scantwell — Wed, 06 Mar 2013 22:15:15 GMT

So if I understand the flow diagram, the decryption policies were based on the URL category (for App-ID) going to (Financial, Healthcare, Shopping, etc), but File Download is AFTER traffic/policy is allowed. Not sure that this quite matches. Can you confirm how this make sense, as I am a little confused. I think I could take a file (and encrypt it) and then zip that file, and put on FTP or web server. I do not think the web server would have the private key that encrypted the packet, although I do agree that a decryption policy would show I am using FTP or some file transfer application. Just not sure if can decrypt the file. I do not think that the FW will have the private key needed to decrypt the file. Much like PGP (pretty good privacy). Thoughts??

Re: Encrypted and Zipped files with virus in it

HITSSEC — Thu, 07 Mar 2013 01:16:37 GMT

The Decryption capabilities are limited to ssl and ssh. Palo Alto currently does not have the ability to decrypt 3rd party encryption programs. Applications using proprietary encryption should be controlled/managed for only business purposes. (limit who can use them or limit the traffic to specific to and from destinations) By doing this you can avoid misuse of the encrypted traffic. Similarily encrypted tunnel traffic should be managed accordingly.

Hope this helps.

Phil

Re: Encrypted and Zipped files with virus in it

mikand — Sat, 09 Mar 2013 08:59:19 GMT

Encrypted tunnels such as ssl and ssh can be denied if the cannot be decrypted.

But what about files?

Is there a way in PA to lets say allow a regular zip file but not an encrypted (passwordprotected) zip-file?

Re: Encrypted and Zipped files with virus in it

mne — Thu, 02 May 2013 13:04:17 GMT

yes, when you specify a file blocking rule on the file types, you can find both "zip" and "encrypted-zip"