Friday, March 27, 2009

Case Studies

The guys over at the Hacking Exposed Computer Forensics blog have been posting a couple of entries that may be of interest to examiners and analysts, called What did they take when they left? In today's economy, and particularly with the news media talking about disgruntled employees taking data or information with them when they leave an employer, this information can be very helpful. Their first post refers to looking for artifacts of CD burning, and part 2 discusses what you might find in the UserAssist key. These are both excellent posts that present more than just dry technical data to the reader...they discuss how the data can be used.

There are some good points raised in part 2, particularly what might have happened if there are no entries in the UserAssist key for the user you're looking at. Based on my experience, one thing I'd point out is to be sure you're looking at the hive file for an ACTIVE user. I can't tell you the number of times that I've seen someone try to run extraction tools across an NTUSER.DAT file from the "Default User" or from the "All Users" profile. I've also seen seasoned examiners try to run tools against the ntuser.dat.log file.

Another point I'd like to expand a bit is that if there are no entries beneath the Count key, or if there don't seem to be a number of entries commensurate with the apparent user activity, be sure to check the LastWrite time of the Count key (particularly if the key has no values at all). Remember, the LastWrite time of a key is similar to the last modification times for files, and the time may correlate directly to when the entries were deleted.

Speaking of which, if you're examining a Windows XP system, don't forget to consider System Restore Points. While the user may have deleted the UserAssist entries from the current hive file, there may be a number of Restore Points that contain valuable data. The upcoming Windows Forensic Analysis second edition includes a discussion of a tool that I wrote to allow the examiner to run RegRipper plugins across the System Restore Points.

Be sure to continue following the posts over at the Hacking Exposed Computer Forensics blog. Folks love a good story, particularly something that they can follow and actually use, and the HECF guys are bringing it on!

Be sure to check out Matt's interview on the Forensic 4Cast podcast, Hogfly's use of HBGary Responder, and Christine's updates at the e-Evidence site.

No comments: