Wednesday, August 17, 2011

Jump List Analysis

Every now and again, I see questions about Windows forensic analysis such as "what's new/different in Windows 7?"  There are a number of things that are different about Windows 7, some of which may significantly impact how analysts approach an examination involving Windows systems.  While there are some aspects of Windows systems that are just different (Windows Event Logs, Registry, etc.), there are some things that are new technologies.

One of those new technologies is Jump Lists. Windows 7 Jump Lists (see the "Jump Lists" section of this post) are a new and interesting artifact of system usage that may have some significant value during forensic analysis where user activities are of interest.  Jump Lists consist primarily of two file types...the *.automaticDestinations-ms (autodest) files, which are created by the operating system when the user performs certain actions, such as opening files, using the Remote Desktop Connection tool, etc.  The specific Jump Lists produced appear to be associated through file extension analysis...if one use double-clicks a text file on one system, it may open in Notepad, whereas on another system it may open in another editor (I like UltraEdit).  The contents of these Jump Lists appear in application context menus on the TaskBar, as well as the Start Menu.  According to Troy Larson, senior forensic dude for MS, these files follow the OLE/compound document format, with individual numbered streams following the LNK file format.  The autodest files also contain a DestList stream, which according to research performed by Jimmy Weg, appears to be an MRU list, of sorts.

There are tools available to view the contents of the autodest files.  For example, you can use MiTeC's SSViewer to open the files and see the various streams.  From here, you would then need to save the numbered streams and use an LNK file viewer to see the contents of the streams.  There's also Mark Woan's JumpLister, which allows you to view the contents of the numbered streams right there in the tool, automatically parsing the LNK formats.  Chris Brown also added this capability to ProDiscover, including a Jump List Viewer in the tool that parses the contents of the numbered streams.

There are also custom Jump Lists, *.customDestinations-ms (customdest) files, which are created when a user "pins" a file to an application, such as via the TaskBar.  Per Troy, these files appear to consist of stacked segments (not in an OLE container) that are LNK file formats.

Both types of files start with a series of hex characters that are the application identifier, or AppID.  This is an identifier that refers to the specific application that the user was using.  While I've found some short lists of references to AppIDs, I haven't yet found a comprehensive list.  Most of what I have found refers to "fixing" Jump Lists by deleting the appropriate files and starting over.

Addendum: Mark McKinnon recently updated the ForensicsWiki page for Jump List IDs.

In an effort to develop a better understanding of the autodest files, I began digging into the Jump List file structure, and wrote some Perl code that parses the *.automaticDestinations-ms (autodest) Jump List files on a binary level.  This parsing capability consists of two Perl modules; the first parses the autodest Jump List files (maintained in MS OLE/Compound File format) and the DestList stream within those files.  The second module parses the numbered streams, which are maintained in the Windows shortcut/LNK file format.  By combining these two modules, I'm able to parse the autodest Jump List files, correlate the DestList stream entries to the numbered streams, and present the available information in any format (TLN, CSV, XML, etc.) I choose.

So far, this is the only tool that I'm aware of that parses the DestList streams.  I had done some research into the format, and it appears that I was able to figure out at least part of the structure of these streams.  I've also found that various applications maintain different information within the contents of the streams...some maintain file names, other maintain string identifiers that appear to be used similar to a GUID.  One thing of interest, and perhaps significant value to an analyst, is that there's a FILETIME object embedded within each structure, and based on Jimmy Weg's research and input, this appears to be an MRU time.  Each individual structure within the DestList stream has a number that is associated with a numbered stream, so the information can easily be correlated to develop a complete picture of what the Jump List contains.

Here's an interesting example of how the information in Jump Lists can be useful; when a user uses the Remote Desktop Connection tool, the "1bc392b8e104a00e.automaticDestinations-ms" Jump List file is created.  The DestList stream of the Jump List file contains the "MRU Time" for each connection, as well as an identifier string.  However, we can correlate each DestList entry to the corresponding numbered stream within the Jump List file, which is itself maintained in the Windows shortcut/LNK file format; as such, we can extract information such as the basename and command line (if it exists) of the shortcut.  If we combine the two, this would appears as:

C:\Windows\System32\mstsc.exe /v:"10.1.1.23"

The information that is available depends upon how the connection was made; for example, rather than an IP address, the command line element of the LNK stream may contain a system name.  However, what we do have is an action associated with a specific user, that occurred at a specific time.  As this is a Windows 7 system, we may also be able to find additional, historic MRU data in Jump Lists accessed via Volume Shadow Copies.

The code is Perl-based and doesn't use any proprietary or platform-specific modules; while it does make heavy use of seek(), read(), substr(), and unpack(), all of these functions are available in all versions of Perl.  Ideally, this code should run on Windows, Linux, and Mac systems equally well (I don't have a Mac to use for testing).

I opted to create Perl modules for this capability because it is a much more flexible method that allows me to incorporate it into other tools.  For example, I can incorporate the modules into a Perl script (which I have done) that will parse through either individual autodest Jump List files or all such files found in a directory, and list the information they contain in any manner that I choose.  Or, I can write a ProDiscover ProScript.  Or, I can (will) include this in my forensic scanner.  Or, to paraphrase Beyonce, "If you like then you better put a GUI on it!"

Output formats are also a matter of personal choice now.  I'm focusing on TLN and CSV formats for the time being, but there's nothing that restricts me to these formats; XML is a possibility (I simply don't have a style sheet format in mind, so I may not pursue this output format).

Issues
Jump Lists are fairly new...although Windows 7 has been out for a while now, I haven't seen a great deal of discussion or questions in public forums or lists looking for more information about these artifacts.  However, some issues have already come up.  For example, I was contacted recently by someone who indicated that one of available tools for parsing Jump Lists "didn't work".  Initial correspondence indicated that at least one Jump List may have been recovered from unallocated space, but it turned out that the three "problem" Jump Lists were from a live acquisition image, and the applications in question could have been open on the desktop during the acquisition.

This presents an interesting and valid issue...how do you deal with Jump Lists from live acquisition images, where the apps were open during the acquisition (live acquisition may be required for a number of reasons, such as whole disk encryption, etc.)?  Or, what about Jump Lists carved from unallocated space?

The answer is that you need to understand the binary format of the Jump Lists (or know someone who is), because that's really the only way to resolve these issues.  When a tool "doesn't work", you need to either have the understanding of the formats to troubleshoot the issue yourself, or go to the tool author for assistance, or go to another resource for that assistance.  If you're squeamish about sharing information about the issue, or the "problem" Jump List file, even with confidentiality agreements in place, then you're really limiting yourself, and by extension, your analysis.  However, this applies to every facet of an examination (Registry, Event Log, USB device analysis, etc.), not just Jump Lists.  So, the answer is to develop the capability internally, or develop trusted resources that you can reach to for assistance.

Summary
From an analyst's perspective, Jump Lists are a new technology and artifact that need to be better understood.  However, at this point, we have considerable information that clearly indicates that these artifacts have value and should be parsed, and the embedded information included in timelines for analysis.  In many ways, Jump Lists contain analytic attributes similar to the Registry and also to Prefetch files, and are tied to specific user actions.  Further research is required, but it appears at this point that Jump Lists also represent a persistent artifact that remains after files and applications are deleted.  In one test, I installed iTunes 10 on my system, and listened to two CyberSpeak podcasts via iTunes.  The Jump Lists persisted even after I removed the application from my system.

Resources
Code Project: Jump Lists
AppID list 1
ForensicsWiki Jump Lists page

5 comments:

Troy said...

I think there is no question that Jump Lists are important artifacts for many cases. The amount of data they maintain is considerable.

What we need to do in the forensics community is compile a list of application IDs. I provided some in my slides, but that list isn't anywhere close to adequate.

Thanks for you work on this.

Troy

Keydet89 said...

Troy,

Thank for you comment. Sorry, I couldn't resist. ;-)

I'm not sure that AppIDs should be a hurdle, as actually parsing the Jump Lists and correlating them with other information on the system (like, through a timeline...) can give you that information.

I think that what's really important here is understanding the value of these artifacts, and where that value can be best realized. There are a lot of "how do I..." questions that are going to come from analysts that will be answered, at least in part, through parsing Jump Lists.

Clommo trust said...

@Troy, Agree with you but still this message is important to pass...

4n6k said...

Harlan,

This was a fantastic post. While the AppID list may not be of *top* priority, I think we can agree that it still holds some value. With that, I've gone ahead and continued adding to the list. I will add them to the ForensicsWiki shortly. I've also written a full blog post with all of the information in addition to resources on Jump Lists. You can view it here:

http://4n6k.blogspot.com/2011/09/jump-list-forensics-appids-part-1.html

Your (and Mark's) work has not gone unnoticed.

-4n6k

Keydet89 said...

Thanks, Dan!