Monday, May 3, 2010

More Experiments with Master File Table Timestamps

I had an anonymous comment on my Tampering with Master File Table Records post referencing the Timestomp utility available in Metasploit. Timestomp is an anti-forensics utility used to change the date/time metadata stored in the $Standard_Information Attribute of the Master File Table. I experimented with the utility prior to the previous post but had some issues getting it to run properly on Windows 7. Moreover, Timestomp does not edit the $File_Name Attribute (MACE) values. The commenter does point out and interesting workaround noted on the Timestomp wiki however.

Moving a file post manipulation with Timestomp copies all four of the $Standard_Information Attribute time values to the $File_Name Attribute Attribute values. Once moved, you must change the SI attribute values again. Staying with using the existing tools available on Windows 7, I tested using the Move-Item Cmdlet.
CD C:\Windows\System32
New-Item malicious.dll -type file
(get-item malicious.dll).creationtime=$(Get-Date "02/11/10 07:30")
(get-item malicious.dll).lastwritetime=$(Get-Date "02/11/10 07:30")
(get-item malicious.dll).lastaccesstime=$(Get-Date "02/11/10 07:30")
set-date -date 02/11/10
set-date -date 07:30:00
rename-item malicious.dll notmalicious.txt
Move-Item notmalicious.txt C:\Users\Public\
CD C:\Users\Public\
(get-item notmalicious.txt).creationtime=$(Get-Date "02/11/10 07:30")
(get-item notmalicious.txt).lastwritetime=$(Get-Date "02/11/10 07:30")
(get-item notmalicious.txt).lastaccesstime=$(Get-Date "02/11/10 07:30")
I verified again by carving the $MFT out and using analyzeMFT to parse the contents. The following is the output of the $MFT record for our malicious file verifying that all eight date values have been edited;

Rob T. Lee also recently posted some research he has been doing on Windows 7 $MFT timestamp entries. His findings to date seem to support the aforementioned behavior. It will be interesting to see what additional behavior he finds. Keep the comments coming!

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