Wildfire & ZIP files

[nthen]

When I have the PE type selected for Wildfire are ZIP files sent to be scanned if they contain EXE files?  I thought they were, but figured I would ask.

[kadak]

Hello nthen,

Yes you are right. Exe files contained in zip files can be forwarded to Wildfire and scanned.

Proof (shows pck2302.zip containing 25 exe files 😞

https://live.paloaltonetworks.com/docs/DOC-5658

As far as PE file types are concerned, currently we support the following extensions -- exe, dll, com, scr, ocx, cpl, sys, drv, tlb

Hope that is the information you were looking for.

Thanks and regards,

Kunal Adak

[nthen]

Just so I am clear...  The only file type I have enabled right now is PE.  Do I need to enable ZIP or is this handled automatically (and then PE types in the zip are scanned).

[Phoenix]

Hello nthen,

Kadak has shared some good knowledge. To add a point, In identifying the PE files with in ZIP files we go 3 iterations down in zip files to see if there is a PE file. So in general they should be extracted and caught by the cloud for PE malware analysis.

[Phoenix]

Will have to add ZIP file types in the file blocking profile to monitor for PE files with in Zip files.

Thanks

[sspringer · Accepted solution]

As long as the session transferring the ZIP has Layer 7 processing enabled, the zip will get decompressed and the PE file will match the File Blocking profile.

It is NOT required to configure File Blocking profile to include ZIP file type.

[Brandon_Wertz]

Got a WF/Zip question.

How does a FW with WF handle multiple levels of zip encoding?  Is there an upper limit of "levels" a file has been zipped?

On a related note any reason why the WF Portal can't accept a zip file?

[reaper]

Hi @Brandon_Wertz

lookee here: Tips & Tricks: Multi-Level Encoding and Blocking (File Blocking Profile)

There may be several reasons zip files are not accepted, possibly to prevent needing to unpack many non-scannable files

[Brandon_Wertz]

@reaper So if I'm understanding correctly a file which has been "zipped" 3 times with the actual file being a .exe could be analyzed for "maliciousness."  If there was a 4th level of zip encoding of maybe some other .docx attached to a .pptx would be beyond the  4 layers of encoding and as such would only be seen as "multi-level encoding" from a WF perspective on the firewall?

[reaper]

yes, a PE file could be in 4 zips deep if sent over a plain connection, but a docx only 3 because the docx itself is encoded, the transport layer itself also counts so if it's sent over http chunk encoding you could only go 3 deep for the PE or 2 for the docx

once the number of levels is exceeded, the file blocking profile (and per extention WildFire) would only see multi-level-encoding and act upon your policy to allow or deny, but no longer forward