Monday, September 03, 2012

Links, Tools, Etc.

Windows 8 Forensics
There is some great information circulating about the Interwebs regarding Windows 8 forensics.  There's this YouTube video titled A Forensic First Look, this blog post that addresses reset and refresh artifacts, the Windows 8 Forensics Guide (this PDF was mentioned previously on this blog), this blog post on the Windows 8 TypedURLsTime Registry key, and Kenneth Johnson's excellent PDF on Windows 8 File History...in addition to a number of other available resources.  Various beta and pre-beta versions of Windows 8 have been out for some time, and with each release there seems to be something new...when I went from the first version available for developers to the Consumer Preview, one of the first things I noticed was that I was no longer able to disable the Metro interface.

So what does all this mean?  Well, just like when Windows XP was released, there were changes that would affect how we within the digital analysis community would do our jobs, and the same thing has been true since then with every new OS release.  While our overall analysis process wouldn't change, there are aspects of the new operating system and it's included technologies that require us to update the specifics of those processes.

Timeline Analysis
Over at the Sploited blog, there's an excellent post on how to incorporate Java information into your TLN-format timeline, in order to help determine the exploit used to compromise a system.  In addition to the information available in the two previous posts (here, and here, respectively), this post includes code for parsing .idx files, and incorporating log entries into a TLN-format timeline.

Just to be clear, this is NOT a RegRipper plugin (there is often times confusion about this...), but is instead a file parser that you can use to incorporate data into your timeline, similar to parsing Prefetch file metadata.  As such, it can very often add some much-needed detail and context to your analysis.

Posts such as this go hand-in-hand with the excellent work that Corey Harrell has done in determining exploit footprints on compromised systems.

PList Parser
If you do forensics on iDevices, or you get access to iDevice backups via iTunes on a system, you might want to take a look at Maria's PList Parser.  Parsing these files can provide you with a great deal of insight into the user's behavior while using the device.  Maria said that she used RegRipper as the inspiration for her tool, and it's great to see tools like this become available.

ScheduledTask File Parser
Jamie's released a .job file parser, written in Python.  These files, on WinXP and 2003 systems, are in a binary format (in later versions of Windows, they're XML) and like other files (ie, Prefetch files) can contain some significant metadata.  In the past, I've found analysis of these artifacts to particularly useful when responding to incidents involving certain threat actors that moved laterally within the compromised infrastructure...one way of doing so was to schedule tasks on remote systems.

Not only does Jamie provide an explanation of what a .job file "looks like", but she also provides references so that folks can look this information up themselves, and develop a deeper understanding of what the tool is doing, should they choose to do so.  Also, don't forget the great work Jamie has done with her MBR parser, particularly if you're performing some sort of malware detection on an acquired image.

Registry Analysis
I ran across this write-up on Wiper recently via Twitter,

In the write-up, the authors state:

"...we came up with the idea to look into the hive slack space for deleted entries."

Hhhmm...okay.  My understanding of "slack space", with respect to the file system, is that it's usually considered to be what's left over between the logical and physical space consumed by a file.  Let's say that there's a file that's 892 bytes, and in order to save it to disk, the system will allocate 2 512 byte sectors, or 1024 bytes.  As such, the slack space would be that 132 bytes that remains between the logical end of the file, and end of the second physical sector.

Now, this can be true for the hive files themselves, as some data may exist between the logical end of the hive, and the end of the last physical sector.  This may also be true for value data, as well...if the 1024 bytes are allocated for a value, but only 892 bytes are actually written to the allocated space, there may be slack space available.

However, if you look at the graphic associated with the comment (excellent use of Yaru, guys!), the first 4 bytes (DWORD) of the selected data are a positive value, indicating that the key was deleted.  As such, the key becomes part of the unallocated space of the hive file, just like the sectors of a deleted file become part of the unallocated space of a volume or disk.  So, the value appears to have been part of unallocated space of the hive file, rather than slack space.

With respect to overall Registry analysis, perhaps "...we came up with the idea..." isn't the most systematic approach to that analysis.  Admittedly, the authors found something very interesting, but I'd be interested to know if the authors found an enum\Root\Legacy_RAHDAUD64 key in that Registry hive they were looking at, or if they found a Windows Event Log record with source "Service Control Manager" and an ID of 7035 (indicating a service start message had been sent), and then opted to check for deleted keys in the hive after determining that there was no corresponding visible keys for a service of that name in the System hive.

Looking for Suspicious EXEs
Adam wrote an interesting blog post on finding suspicious PE files via clustering...in short, assuming PE files may have been subject to timestomping (ie, intentional modification of MFT $STANDARD_INFORMATION attribute time stamps), and attempting to detect these files by "clustering" the PE file compile times.

You can read more about methods for detecting malicious files by reading Joel Yonts' GIAC Gold Paper, Attributes of Malicious Files.

3 comments:

Jimmy_Weg said...

Kenneth Johnson's excellent PDF on Windows 8 File History..

In addition to what's described, it seems that Previous Versions, as we know it in Win 7, is gone. No more context menu (at least in my test build of 8 Enterprise). File History means that we need the backup drive. System Restore remains, at least for now. There is a "History" option in Explorer, but it wants the File Hostory drive.

digitalx00 said...

Completely off topic, but I couldn't find a way to contact you, so here it is: Any way to look at doing forensics on Terminal Servers? Interesting.

Keydet89 said...

digitalx00,

Well, you didn't leave any way for me to contact you, so I'll answer you here...yes, I just finished up a report for a Win2008R2 system running Terminal Services today.

you can reach me at keydet89 at yahoo dot com