Thursday, March 19, 2009

What did they take when they left? Part 1 - Detecting CD Burning

Dear Reader,

We've been discussing server level analysis for the last couple posts but there is plenty to talk about on the desktop. This will be a multi part series discussing different artifacts that we can recover that give us provable facts regarding a user's activity. It is easy to speculate on actions based on speculative data such as access data or related files or dll's accessed on a system but it is always better to rely on a repeatable process that creates a specific artifact each time to explain a user's action.


We only do cases that either lead to civil litigation or are in the process of civil litigation (no criminal work). One of our most common requests is the question, before this employee left did they take any documents with them. There are several places on a system we check to determine if a user has taken a document from the system in some fashion (CD, USB Drive, Emailed out, printed, etc…) and in this post we will discuss how to determine if a user has burned a CD. If you are examining a Windows XP or Windows Server 2003 (I have not been able to test this on Vista or server 2008 yet) image then the system event log will contain eventids 7036 and 7035 as it was generated by the Service Control Manager and will contain in the description a string starting with The IMAPI CD-Burning Service. There will be one such set of entries showing the service starting and stopping on each reboot but any entry not close to a reboot will indicate that a CD is being burned from this system.


An example of a burning entry, yes my machine is named HOSS:

12/11/2008

3:04:13 PM

Service Control Manager

Information

None

7036

N/A

12/11/2008

3:04:13 PM

Service Control Manager

Information

None

7035

NT AUTHORITY\SYSTEM

12/11/2008

3:04:22 PM

Service Control Manager

Information

None

7036

N/A

HOSS

The IMAPI CD-Burning COM Service service entered the running state.

HOSS

The IMAPI CD-Burning COM Service service was successfully sent a start control.

HOSS

The IMAPI CD-Burning COM Service service entered the stopped state.

Sorry for the bad editing here, the full row will not fit in this blog template. The line starts with the date and then continues in the block below. There is one date for each of the IMAPI entries.

If those three entries are not part of a reboot/startup sequence then you have found a user burning a CD. These entries do not have to be in uninterrupted sequence as you see here, but there should be a start and a stop to show a successful burn. This is not just for CDs burned by Windows directly, third party applications will also call this service when burning a CD. You can estimate the size of the data burned to the disk by determining the number of minutes spent burning (the time between the start and stop of the service) multiplied by the write speed of the CDROM. This also applies to DVDs.


I will not discuss how to determine if a CD was accessed in this post as that is material for Part 2 – What was accessed from external drives.


Update: As per the comments below, more activities than just booting and burning will cause these event log entries to show up. I will be doing some more testing to find a better answer.