If you tell enough stories, perhaps the moral will show up.


Light Feet on the Drive

OK -- the scenario is that you really, really want to know what's on a Windows workstation hard drive -- you plan to look in the IE cache, system logs, registry, SAM, etc. You can't/won't be arsed to image it and work on the image and you are not going to take this rather urgent moment to learn about excellent Linux based tools. But you do want to take all reasonable precautions. (What's reasonable? I'm less sure than I was after reading this document. It's a normally reliable source, but the example scenario contains an eyepopping amount of work on a live system. Maybe evidence rules are different in the States. My approach is to kill the disk and only ever read from it.) Here's the plan.

  1. Prepare an investigation machine. You need a computer with Internet access where you can work privately. You also need a USB disk housing that will fit the disk in question. Maplin do an IDE/SATA for 3 1/2 inch disks, while 2 1/2 inch laptop disks still seem to be small format IDE and there are lots of housings for those. Since we really don't want to write to the evidence disk, run the Read Only registry file below, and test that you can't write to a scratch USB device. Load tweakui (Microsoft Powertoys) and make sure that you're not set to autoplay anywhere to reduce the risk of malwaring your investigation machine.
  2. Give the job a name. The Remedy number, "2007 02 Hotmail Complaint" -- whatever.
  3. Get a chain of custody log. The idea here is that you have a collection of evidence for the investigation, and as you collect each item, you sign it out and and back in when you return it. so that you can swear to where anything was at any future tribunal.
  4. Get a log book. Or open a file, or something, anything where you can write everything down. Computer records are good here as you can paste in log entries and images. Finish each day with next steps so you don't forget, then print the day's record, and sign and date each page. Enter it into your evidence store.
  5. Pull the power on the workstation. Record make model and serial number. Remove the disk, and record the make, model and serial. Put this diskless carcass into your evidence store with a label that says "2007 02 Hotmail Complaint Exhibit A". You shouldn't need to boot it, but you never know. Anyway it's evidence.
  6. The disk is Exhibit B. Log it, and sign it out to yourself. Mount it in the USB housing. Check that you've run readonly.reg on your investigation machine. Plug it in and make sure it comes up on you're investigation machine. Don't let it auto play.
  7. Where you go now is up to you. Check the tools below to look at Windows file contents, and there are others to look at file times.
Read Only.reg

Create a file called readonly.reg using notepad. Save it on your desktop. The file contains just these lines:

Windows Registry Editor Version 5.00

Double click on the file and confirm you do want to load the settings. Then test on a scratch USB stick -- you should see a "Write Protect" warning come up when you try and save something. To get back to read/write you need another file with that last dword set to 00000000.

Read Event Log Files

The log files you want will be in d:\windows\system32\config\ assuming d: is where your disk is. Sometimes you can load the .evt files from the subject disk into the log viewer. I find that it always says they're corrupt though.

So I use Activestate Perl, add the Parse::EventLog module and a few lines of code to list them out into an easy text format. Here's the code -- you'll want to tweak it.

use strict;
use Parse::EventLog;

my $elogfn = 'd:\\windows\\system32\\config\\SecEvent.Evt';
print "Loading Event log: $elogfn .." ;
my $elog = Parse::EventLog->new($elogfn);
print "..loaded\n";
my %c = $elog->getOldestEvent();
while (%c = $elog->getNextEvent())
  my $str;
  if ($c{Strings})
      $str = join('|', @{$c{Strings}}) ;
      $str =~ s/\t/\\t/g;
      $str =~ s/  / /g;
  my $evt = $c{EventID};
  my $time = localtime($c{TimeGenerated});

  my $ msg = "$time: $evt <$str>\n";
  print $msg unless grep({$_ == $evt} (560, 576, 515, 600));

The good bit here, is that this will work from a Linux machine just as well as Windows.

Read Registry and SAM files

The most amazing thing thing I've learnt recently is that the SAM is in the same format as a registry hive. This means you can use this tool to print out the system registry and the SAM (from d:\windows\system32\config\) as well as user registry from ntuser.dat in the appropriate profile.

You should also be able to use Parse::Win32Registry though I haven't done that. It would work from Linux, too. There's scope for a useful script here, as the SAM is in a desperately unhelpful format.

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