SANS Digital Forensics and Incident Response Blog: Tag - dd

Digital Forensics Case Leads: Ready, Forensicate, Aim

Ready. Forensicate. Aim. Okay, seriously, don't do that. You know the correct order, right? If not, Chris Pogue spent part of last year presenting on the Sniper Forensics methodology, developed by the incident response team at TrustWave's SpiderLabs, and has what you need. Even if you already know the proper order is Ready, Aim, Forensicate, … Continue reading Digital Forensics Case Leads: Ready, Forensicate, Aim


An anti-forensics dd primer

dd is the swiss army knife of file tools - with /dev/tcp it can also be a network tool (but nc is simpler).

First we need the basics for dd. For this we have the man page and some definitions. I have taken (blatantly paraphrased) the man file info for dd and included this below (which is simple to obtain - "man dd").

For the purpose of a task such as reversing files and swapping them, we need to concentrate on the following options:

  • bs - This is block size. Setting "bs=1" means that we can use dd as a bit level (instead of a block level tool). Although it does slow down the process from a block copy, we are not looking at how fast we can copy here.
  • skip - this tells us to skip "n" blocks. In our case, we want "n" bits.

What we are going to do is start at the value of "n" set to our last bit in the file. We will loop the dd function to next copy bit "n - 1", then "n - 2", ... to

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Bring Me My Pipe

[caption id="attachment_298" align="alignleft" width="180" caption="Pipes photo courtesy of tanakawho at flickr.com "]//flickr.com/photos/28481088@N00/[/caption]

Often used and under appreciated, the pipe feature in unix/linux/dos has to be my favorite tool in incident response and forensics.

Need the device at /dev/sda imaged with progress indicators and an md5sum?

dd if=/dev/sda| pipebench | tee sda.dd | md5sum >sda.md5.txt

Need a summary of the unique hosts from Internet Explorer's index.dat history file?

pasco index.dat | grep -v 'javascript\\:' | egrep -i 'ftp|http' | sort -k 4 | awk '{print $3}' | awk

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