Tools for extracting files from pcaps

Published: 2009-08-13
Last Updated: 2009-08-16 00:42:14 UTC
by Jim Clausing (Version: 2)
8 comment(s)

Often in the course of investigating a compromised machine or when analyzing malware in a sandnet or honeynet, I will have a complete capture of all the network activity in a pcap file and I want to pull out any files that were downloaded by the infected machine.  Unfortunately, I have not found any really good tools that allow me to full files from lots of different types of traffic.  A couple of years ago, I put together a perl script that used tcptrace and the HTTP::Response perl module to pull downloaded files out of HTTP traffic, but what about other forms of traffic?  FTP?  SMTP?  unknown TCP or UDP?  whatever?  My ideal tool would be able to reassemble the packets, discard headers, etc.  Well, the other day I noticed a post on Darknet about Xplico that might be (at least the basis of) the magic tool I'm looking for.  I'm just starting to play with it, but I figured this might be a good time to ask our readers what they use?  You can send us e-mail, use the contact form, or leave a comment.  Thanx in advance.

Update: 2009-08-16 00:15 GMT (jac)  A huge thanx to all who wrote in, here are some of the tools you suggested.

Jim Clausing, jclausing --at-- isc dot sans dot org

8 comment(s)


chaosreader is also a good tool to extract traffic from pcaps.
the dsniff suite is still hard to beat - even supports capturing NFS files!

However, the one I'm really hanging out for - but can't fine a solution for - is CIFS/SMB. i.e. Microsoft network file sharing. Does anyone know of an open source product that can recreate CIFS files? Hell, even getting their filenames reliably off the stream would be great.

The best program I've found for this is Network Miner. To quote the site:

'NetworkMiner can also parse PCAP files for off-line analysis and to regenerate/reassemble transmitted files and certificates from PCAP files.'

You can either sniff using it (and perhaps something else for ARP Poisoning), or just feed it pcap files. It extracts a lot of information about the hosts, rather than just showing you the actual packets. Windows only, I'm afraid, but very useful. Give it a try.
NetWitness can extract files and much much more.

Check out the youtube videos too:
As mentioned by others, I would recommend chaosreader and dsniff. In addition, I would also recommend:

These utilities (and others) can be found on my Security Onion LiveCD:
Another tool worth mentioning is xplico,
Another one I find useful - tftpgrab
I tried these programs when I was doing an investigation and found I liked NetWitness the most. None of them created a good timeline like I wanted.

• Chaosreader
• NetworkMiner
• NetWitness Investigator
• Wireshark
• NeSA commercial program, I did not like this program

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