Good Reading, Tools

Reading
Cylance Blog - Uncommon Event Log Analysis - some great stuff here showing what can be found with respect to indirect or "consequential" artifacts, particularly within the Windows Event Logs on Vista systems and above.  The author does a pretty good job of pointing out how some useful information can be found in some pretty unusual places within Windows systems.  I'd be interested to see where things fall out when a timeline is assembled, as that's how I most often locate indirect artifacts.

Cylance Blog - Uncommon Handle Analysis - another blog post by Gary Colomb, this one involving the analysis of handles in memory.  I liked the approach taken, wherein Gary explains the why, and provides a tool for the how.  A number of years ago, I had written a Perl script that would parse the output of the MS SysInternals tool handle.exe (ran it as handle -a) and sort the handles found based on least frequency of occurrence, in order to do something similar to what's described in the post.

Security BrainDump - Bugbear found some interesting ZeroAccess artifacts; many of the artifacts are similar to what is seen in other variants of ZA, as well as in other malware families (i.e., file system tunneling), but in this case, the click fraud appeared in the systemprofile folder...that's very interesting. 

SpiderLabs Anterior - The White X - this was an interesting and insightful read, in that it fits right along with Chris Pogue's Sniper Forensics presentations, particularly when he talks about 'expert eyes'.  One thing Chris is absolutely correct about is that we, as a community, need to continue to shift our focus away from tools and more toward methodologies and processes.  Corey Harrell has said the same thing, and I really believe this to be true.  While others have suggested that the tools help to make non-experts useful, I would suggest that the usefulness of these "non-experts" is extremely limited.  I'm not suggesting that one has to be an expert in mechanical engineering and combustion engine design in order to drive a car...rather, I'm simply saying that we have to have an understanding of the underlying data structures and what the tools are doing when we run those tools.  We need to instead focus on the analysis process.

Java Web Vulnerability Mitigation on Windows - Great blog post that is very timely, and includes information that can be used in conjunction with RegRipper to in order to determine initial infection vector (IIV) during analysis.

ForkSec Blog - "new" blog I saw referenced on Twitter one morning, and I started my reading with the post regarding the review of the viaExtract demo.  I don't do any mobile forensics at the moment, but I did enjoy reading the post, as well as seeing the reference to Santoku Linux.

Tools
win-sshfs - ssh(sftp) file system for Windows - I haven't tried this one but it does look interesting.

4Discovery recently announced that they'd released a number of tools to assist in forensic analysis.  I downloaded and ran two of the tools...LinkParser and shellbagger.  I ran LinkParser against a legit LNK file that I'd pulled from a system that contained only a header and a shell item ID list (it had no LinkInfo block), and LinkParser didn't display anything.  I also ran LinkParser against a couple of LNK files that I have been using to test my own tools, and it did not seem to parse the shell item ID lists.  I then ran shellbagger against some test data I've been working with, and found that, similar to other popular tools, it missed some shell items completely.  I did notice that when the tool found a GUID that it didn't know, it said so...but it didn't display the GUID in the GUI so that the analyst could look it up.  I haven't yet had a chance to run some of the other tools, and there are reportedly more coming out in the future, so keep an eye on the web site.

ShadowKit - I saw via Chad Tilbury on G+ recently that ShadowKit v1.6 is available.  Here's another blog post that talks about how to use ShadowKit; the process for setting up your image to be accessed is identical to the process I laid out in WFAT 3/e...so, I guess I'm having a little difficulty seeing the advantages of this tool over native tools such as vssadmin + mklink, beyond the fact that it provides a GUI.

Autopsy - Now has a graphical timeline feature; right now, this feature only appears to include the file system metadata, but this approach certainly has potential.  Based on my experience with timeline analysis, I do not see the immediate value in this approach to bringing graphical features to the front end of timeline analysis.  There are other tools that utilize a similar approach, and as with those, I don't see the immediate value, as most often I'm not looking for where or when the greatest number of events occur, but I'm usually instead looking for the needle in stack of needles.  However, I do see the potential for the use of this technique in timeline analysis.  Specifically, adding Registry, Windows Event Log, and other events will only increase the amount of data, but one means for addressing this would be to include alerts in the timeline data, and then show all events as one color, and alerts as another.  Alerts could be based on either direct or indirect/consequential artifacts, and can be extremely valuable in a number of types of cases, directing the analyst's attention to critical areas for analysis.

NTFS TriForce - David Cowen has released the public beta of his NTFS TriForce tool. I didn't see David's presentation on this tool, but I did get to listen to the recording of the DFIROnline presentation - the individual artifacts that David describes are very useful, but real value is obtained when they're all combined.

Auto-rip - Corey has unleashed auto-rip; Corey's done a great job of automating data collection and initial analysis, with the key to this automation being that Corey knows and understands EXACTLY what he's doing and why when he launches auto-rip.  This is really the key to automating any DFIR task..while some will say that "it goes without saying", too often there is a lack of understanding with respect to the underlying data structures and their context when automated tools are run.

WebLogParser - Eric Zimmerman has released a log parser with geolocation, DNS lookups, and more.

Plugin: SAMParse

I thought I'd take a moment to discuss the samparse.pl plugin.  This plugin parses the SAM hive file for information regarding user accounts local to the system itself, as well as their group membership, both of which can be very valuable and provide a good amount of insight for the analyst, depending upon the case.  The information retrieved by this plugin should be correlated against the output of the profilelist.pl plugin, as well as the user profiles found within the file system.

One of the initial sources for parsing the binary data maintained within the SAM hive is the Offline Windows Password and Registry Editor.  There is also a good deal of useful information in this AccessData PDF document.

An interesting piece of information displayed by this plugin, if available, is the user password hint.  This capability was part of the plugin starting on 20 Oct 2009 (the capability was included in XP), and discussed by SpiderLabs almost 3 years later. This may provide useful information for an analyst...I have actually seen what turned out to be the user's password here!

Perhaps one of the most confusing bits of information in the output of the samparse.pl plugin is the "Password not required" entry.  This is based on a check of a flag value, and means just that...that a password is not required.  It does NOT mean that the account does not have a password...it simply means that one is not required.  As such, you may find that the account does, indeed, have a password.  I've seen posts to various forums and lists that either ask about this setting, or simply state that the output of RegRipper is incorrect.  I am always glad to entertain and consider issues where the interpretation of a Registry value or data flag setting is incorrect, particularly if it is supported with solid data.

If you're analyzing a Vista or Windows 7 system and run across something suspicious regarding the local user accounts, remember that you will have a copy of the SAM hive in the Windows\system32\config\RegBack folder that you can incorporate into your analysis, and that you may also have older SAM hives in available VSCs.

Finally, there's a version of this plugin that provides timeline (TLN) output for various bits of time stamped date, to include account creation date, the password reset date, the last password failure date, and the last login.  Incorporating this into your timeline, along with the historical information available in other Registry resources (such as those mentioned in the above paragraph), can provide considerable insight into user activity on the system.

Resources
MS KB305144 -
Scripting Guy blog, 7/7/2006

The Tool Validation "Myth-odology"

I posted recently about understanding data structures, and I wanted to continue with that thought process and line of reasoning into the area of the current state of tool validation.

What we have seen in the community for some time is that a new tool is announced or mentioned, and members of the community begin clamoring for their copy of that tool. Many times, one of the first questions is, "where can I download a copy of the tool?"  The reasons most give for wanting to download a copy of the tool is so that they can "test" it, or use it to validate the output of other tools.  To that, I would pose this question - if you do not understand what the tool is doing, what it is designed to do, and you do not understand the underlying data structures being parsed, how can you then effectively test the tool, or use that tool to validate other tools?

As such, the current state of tool validation, for the most part, isn't so much a methodology as it is a myth-odology.  Obviously, this isn't associated with testing and validation processes such as those used by NIST and other organizations, and applies more to individual analysts.

There are tools out there right now that are being recommended as being THE tool for parsing a particular artifact or set of artifacts.  The tools are, in fact, very good at what they do, but the fact is that some of them do not parse all of the data structures available within the set of artifacts, nor do they identify the fact that they're missing these structures in their output.  I'm aware of analysts who, in some cases, have stated that the fact that the tool doesn't parse and display specific artifacts isn't an issue for them, because the tool showed them what they were looking for.  I think what's happening is that someone will run a tool against a data set, see a lot of data in the output, and deem it "good".  They may then run another tool against the same data set, see different output, and deem one of the tools "not good" or at the very least, "questionable".  What I don't think is happening is that analysts are testing the tools against the data structures themselves, viewing the data itself as a 'blob' and relying on the tools to provide that layer of abstraction I mentioned in my previous post.

Consider the parsing of shell items, and shell item ID lists.  These artifacts abound on Windows systems, more so as the versions of Windows increase.  One place that they've existed for some time is in the Windows shortcuts (aka, LNK files).  Some of the tools that we've used for years parse both the headers and LinkInfo blocks of these files, but it's only been in the past 12 - 18 months or so that tools have parsed the shell item ID lists.  Why is this important?  These blog posts do a great job of explaining why...give them a read.  Another reason is that over the past year or so, I've run across several LNK files that consisted solely of the header and the shell item ID list...there was no LinkInfo block to parse.  As such, some of the tools that were available at the time would simply return blank output.

There is also the issue of understanding how a tool performs it's function.  Let's take a look at the XP Event Log example again.  Tools that use the MS API for parsing these files are likely going to return the "corrupted file" message that we're all used to seeing, but tools that parse the files on a binary level, going record-by-record, will likely work just fine.  

Another myth or misconception that is seen too often is that the quality of the tool is determined by how much space the output consumes. This simply is not the case.  Again, consider the shell item ID lists in LNK files.  Some of the structures that make up these lists contain time stamps, and a number of tools display the time stamps.  What do these time stamps mean?  How are they generated/produced?  Perhaps equally important is the question, what format are the time stamps saved in?  As it turns out, the time stamps are DOSDate format, consuming 32-bits and having a 2 second granularity.  On NTFS systems,  a folder entry (that leads to the target file) that appears in the shell item ID list will have a 64-bit FILETIME time stamp converted to a 32-bit DOSDate time stamp, with a corresponding loss in granularity.  As such, it's important to not only understand the data structure and its various elements, but also the context of those structure elements.  As such, if one tool lists all of the elements of the component data structures, and another does not, is the second tool any less valid or correct?

Returning to the subject of data structures, does this mean that every analyst must know and understand the details for every available data structure on, say, a Windows system?  No, not at all...that's simply not realistic.  The answer, IMHO, is that analysts need to engage.  If you're unclear about something, ask.  If you need a reference, ask someone.  There are some great structure references posted on the ForensicsWiki, including those posted by Joachim Metz, but I think that far too few analysts use that site as a resource.  By sharing what we know, and coupling that with what we need to know, we can approach a better method for validating the tools and methodologies that we use.

Understanding Data Structures

Sometimes at conferences or during a presentation, I'll provide a list of tools for parsing a specific artifact (i.e., MFT, Prefetch files, etc.), and I'll mention a tool or script that I wrote that presents specific data in a particular format.  Invariably when this happens, someone asks for a copy of the tool/script.  Many times, these scripts may not be meant for public consumption, and are only intended to illustrate what data is available within a particular structure.  As such, I'll ask why, with all of the other available tools, someone would want a copy of yet another tool, and the response is most often, "...to validate the output of the other tools."  So, I'm left wondering...if you don't understand the data structure that is being accessed or parsed, how is having another tool to parse it beneficial?

Tools provide a layer of abstraction over the data, and as such, while they allow us access to information within these data structures (or files) in a much more timely manner than if we were to attempt to do so manually, they also tend to separate us from the data...if we allow this to happen.  For many of the more popular data structures or sources available, there are likely multiple tools that can be used to display information from those sources.  But the questions then become, (a) do you understand the data source(s) being parsed, and (b) do you know what the tool is doing to parse those data structures?  Is the tool using an MS API to parse the data, or is it doing so on a binary level? 

A great example of this is what many of us will remember seeing when we have extracted Windows XP Event Logs from an image and attempted to open them in the Event Viewer on our analysis system.  In some cases, we'd see a message that told us that the Event Log was corrupted.  However, it was very often the case that the file wasn't actually corrupted, but instead that our analysis system did not have the appropriate message DLLs installed for some of the records.  Microsoft does, however, provide very clear and detailed definitions of the Event Log structures, and as such, tools that do not use the Windows API to parse the Event Log files can be used to much greater effect, to include parsing individual records from unallocated space.  This could not be done without an understanding of the data structures.

Not long ago, Francesco contacted me about the format of  automaticDestinations Jump List files, because he'd run a text search across an image and found a hit "in" one of these files, but parsing the file with multiple tools gave no indication of the search hit.  It turned out that understanding the format of MS compound file binary files provides us with a clear indication of how to map unallocated 'sectors' within the Jump List file itself, and determine why he'd seen a search hit 'in' the file, but that hit wasn't part of the output of the commonly-used tools for parsing these files.

Another great example of this came my attention this morning via the SQLite: Hidden Data in Plain Sight blog post from the Linuxsleuthing blog.  This blog post further illustrates my point; however, in this case, it's not simply a matter of displaying information that is there but not displayed by the available tools.  Rather, it is also a matter of correlating the various information that is available in a manner that is meaningful and valuable to the analyst.

The Linuxsleuthing blog post also asks the question, how do we overcome the shortcomings of the common SQLite Database analysis techniques?  That's an important question to ask, but it should also be expanded to just about any analysis technique available, and not isolated simply to SQLite databases.  What we need to consider and ask ourselves is, how do we overcome the shortcomings of common analysis techniques?

Tools most often provide a layer of abstraction over available data (structures, files, etc.), allowing for a modicum of automation and allowing the work to be done in a much more timely manner than using a hex editor.  However, much more is available to us than simply parsing raw data structures and providing some of the information to the analyst.  Tools can parse data based on artifact categories, as well as generate alerts for the analyst, based on known-bad or known-suspicious entries or conditions.  Tools can also be used to correlate data from multiple sources, but to really understand the nature and context of that data, the analyst needs to have an understanding of the underlying data structures themselves.

Addendum
This concept becomes crystallized when looking at any shell item data structures on Windows systems.  Shell items are not documented by MS, and yet are more and more prevalent on Windows systems as the versions progress.  An analyst who correctly understands these data structures and sees them as more than just "a bunch of hex" will reap the valuable rewards they hold.

Shell items and shell item ID lists are found in the Registry (shellbags, itempos* values, ComDlg32 subkey values on Vista+, etc.), as well as within Windows shortcut artifacts (LNK files, Win7 and 8 Jump Lists, Photos artifacts on Windows 8, etc.).  Depending upon the type of shell item, they may contain time stamps in DOSDate format (usually found in file and folder entries), or they may contain time stamps in FILETIME format (found in some variable type entries).  Again, tools provide a layer of abstraction over the data itself, and as such, the analyst needs to understand the nature of the time stamp, as well as what that time stamp represents.  Not all time stamps are created equal...for example, DOSDate time stamps within the shell items are created by converting the file system metadata time stamps from the file or folder that is being referred to, reducing the granularity from 100 nanoseconds to 2 seconds (i.e., the seconds value is multiplied times 2).

Resources
Windows Shellbag Forensics - Note: the first colorized hex dump includes a reported invalid SHITEM_FILEENTRY, in green; it's not actually invalid, it's just a different type of shell item.

There Are Four Lights: Incident Response

When I first thought of what became the Forensic Scanner (free version available here), my goal was to provide a solution for getting analysts to the point of analyzing images acquired from systems sooner; that is, to optimize an analyst's time when it comes to dead-box analysis.  Taking a page from Deming's book, my approach was to take a look at what could be optimized, and I figured that getting analysts to the point of actually doing analysis faster, by automating those tasks that we tend to do over and over again would be a great way to speed things up a bit.

The Forensic Scanner was designed to be used by mounting an acquired image on your analysis system as an accessible volume.  You can mount acquired images using FTK Imager, ImDisk, ProDiscover, or even converting the image to a VHD using vhdtool.

One of the things that's come up since I started talking about the Forensic Scanner is the question of whether this tool can be used in the triage of live systems.  Now, the Scanner was not designed for this purpose, particularly because some of the Perl modules used do not work against the Registry on a live system - a different API is required.  However, as it turns out, with the right tools, you can, in fact, use the Forensic Scanner to triage remote live systems.  For example, if you have F-Response, you can use the Forensic Scanner to retrieve information from remote live systems. I've also heard from one person recently that they were able to use the Forensic Scanner via EnCase PDE.  I don't have any specifics about how they did this, and I am unable to test this myself.

If you don't have access to either of these tools, but still want to use the Forensic Scanner in an infrastructure, take a look at Andrew Hay's post regarding the NBDServer application.  His methodology is a bit involved, but from the perspective of trying to perform remote incident response on a shoe-string budget, the only "costs" involved are two systems (or a VM or two...) and a bit of a learning curve.

RegRipper Updates

I've made some updates to RegRipper that I wanted to let everyone know about, in case you want to take advantage of them.

Version 2.8 is a minor update, and includes an additional function/subroutine that is available to the plugins: alertMsg().  In short, the tools (RegRipper, rip) provide the functionality, which is then used by the plugins themselves.  The updates to the tools simply provide the functionality; several of the plugins have been updated to make use of that functionality.  If you'd like to use this functionality, then you want to download the files rrv2.8.zip and plugins20130429.zip.

How is this alertMsg() function useful?  Well, consider Corey's recent post regarding the soft_run.pl and user_run.pl plugins; in the post, he illustrates several values of interest, that point (in his case) to malware.

As such, I added two checks to both of the plugins; one checks for "Temp" or "temp" in the path found in the value data (this would catch "Local Settings\Temp", "Temporary Internet Files", and "Templates"), and the other checks to see if the path in the value data ends in ".com" or ".bat". 

Other updated plugins include (but are not limited to):

• appinitdlls - generate an alert if the value is not blank
• appcompatcache - generate an alert for any path that includes "[Tt]emp"
• attachmgr - generates alerts per Corey's blog post (ref: KB883260)
• imagefile - generate an alert if a Debugger value is found
• user_run, soft_run - alert on paths that contain "[Tt]emp"
• winlogon, winlogon_u - added several alerts

What this means is that for RegRipper (the GUI), any alerts generated by the plugins will be added to the end of the report file, and for rip.exe, any alerts will appear last in the output.  The purpose of this is to allow analysts to focus on what might be most important to them.  Many of the plugins are meant to provide information for the analyst to review and use, and therefore will not generate alerts (nor need to).  However, other plugins (such as those described in this post) include specific items that can be checked, and if found, an alert can be generated.  This does not mean that the output of the plugin will not be generated; in fact, quite the opposite occurs.  The alerts are generated in addition to the output of the plugins.

So a big question is going to be, where do the alerts come from? The answer is pretty simple...they come from stuff I, and others (specifically, Corey Harrell), have seen.  For example, one of the checks that occurs in the soft_run.pl and user_run.pl plugins is that every value data (i.e., path) is checked to see if it contains "[Tt]emp"; an alert will be generated if it contains "Templates", "Local Settings\Temp", or "Temporary Internet Files", for example.  This is important because (a) I've seen applications set to run from those paths, and (b) you generally don't want that sort of thing to happen, particularly from "Temporary Internet Files".

Now, there are two things to keep in mind...the first is that not all plugins will necessarily generate alerts.  Some plugins, such as networklist.pl, do not necessarily provide information that should be alerted on.  The output of this plugin is mostly for informational purposes, and you should check it if you're looking for something specific.  Other plugins do provide information that can be alerted on; for example, in winlogon.pl, one alert will be generated if the TaskMan value is found, and another will be generated if the Userinit value is found to have more than simply what is expected.  Someplace that this might be useful...look for alerts from the winlogon.pl plugin, which would detect Ramnit.

The second is that of the plugins that do generate alerts, they will only generate those alerts that are included in (i.e., coded into) the plugins.  You can see what is generating an alert by locating any instance of ::alertMsg() in the plugin, and taking a look at the code around it.  If a plugin isn't alerting on something that you want, it may be because that alert hasn't shared that with someone...so just send me an email and I'll see what I can do (note: I may need sample data in order to test it).

Several of the plugins that were updated to include this ::alertMsg() functionality have also been converted to TLN output so that the alerts can be included in a timeline.  My hope is that this will bring a considerable modicum of intelligence to timeline analysis, by including things that would be of interest directly in the timeline.  In many cases, the location of the alert in the timeline may be imprecise...the time stamp value is based on the LastWrite time of the key; however, my hope is that seeing an event source of "ALERT" in the timeline (which you search on using Notepad++, etc.) will raise awareness of areas that should be checked by bringing them to the attention of the analyst.

A caveat...if you're using ripXP (is anyone using that??), then you want to use the plugins in the archive for 18 April 2013.  I'll leave that archive up and available, but I will not be updating ripXP with the alertMsg() functionality, so you'll need to use the appropriate plugins.  This is easy to do, simply create a separate folder for ripXP.

RegRipper Plugin Updates

The RegRipper plugin archive has been updated.

The archive contains a text file that lists the updates, which are also listed here.  The wiki also contains a Plugins page, where descriptions of plugins (what they check, what they're intended for, how to use the data, etc.) will be maintained.

Plugin: Winlogon

The Winlogon plugin is a pretty comprehensive plugin, in that since the RegRipper consolidation release, several plugins have been retired and their functionality incorporated into this one plugin.

The Winlogon plugin is a valuable resource when it comes to determining autostart information for the system.  For example, the UserInit and Shell values point to the shell that is launched when a user logs in.  From here:

The Winlogon key controls actions that occur when you log on to a computer running Windows 7. Most of these actions are under the control of the operating system, but you can also add custom actions here. The “HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit” and “HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell” subkeys can automatically launch programs. 

 MS KB 555648 addresses an issue where either the Shell or Userinit values have been modified.

The Winlogon plugin extracts values and data from beneath the HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon key, as well as it's accompanying Wow6432Node cousin on 64-bit Windows systems, and it also collects information from several subkeys, as well.

This Microsoft page provides additional information about some of the values that appear beneath this key.  Another way that a value beneath this key can be used to subvert the system is to add the TaskMan value, and point to malicious software.

Notify
This subkey maintains a running list of functionality made available to Windows systems via notification packages.  In short, a "package" (DLL) can receive notifications from Windows when certain events occur.  When these events occur, Windows will look for the package and launch the handler for that specific event.  For example, you can have specific functions run automatically when a user logs on, locks the console, when a smartcard is plugged into the system, etc.

As with other functionality on Windows system, this also provides a great mechanism for malware (see this Cutwail example) persistence.

Special Accounts
One of the subkeys that can exist beneath the Winlogon key is the "SpecialAccounts\UserList" subkey.  The values beneath this key, and each value's accompanying data, determines whether or not the specific account appears on the Welcome screen.  Very often, this information is used to for legitimate purposes, so that the screen isn't cluttered with accounts that are not used for logging into the system at the console.  However, this functionality can be, and has been, used for malicious purposes.  I've seen this in the wild, most often when an intruder has accessed an infrastructure via RDP, and creates accounts on systems that they can use to log in; hiding the user account from the Welcome screen prevents legitimate users from seeing anything suspicious when the system is rebooted.  In one instance, I saw this being used, but the "SpecialAccounts" key had been misspelled, so the functionality was not enabled.

The Winlogon plugin encapsulates data from several plugins, which led me to retire those other plugins.  For example, I added the checks from the taskman.pl, notify.pl, and specaccts.pl plugins to the winlogon.pl plugin, and retired those other plugins.  All of this will appear in the history file associated with the next roll-out of the plugin archive.  The output of the winlogon.pl plugin also includes analysis notes, so that the analyst has information right there in the report with respect to what they should look for, and what might be suspicious.

Resources
Winlogon\Nofity entries
MS KB 102972: Explains many of the Winlogon values

Plugin: specaccts.pl

As is the case with many of the RegRipper plugins, the specaccts.pl plugin initially came about because of something I read about, and after running it, it actually found what I was looking for in the wild.

Beneath the Winlogon key (specifically, HKLM\Software\Microsoft\Windows\CurrentVersion\Winlogon), there may be a subkey path of "SpecialAccounts\UserList".  The values listed beneath the UserList key would be user account names, and if the data associated with a value is "0", then that account will not appear on the Welcome screen (any value greater than 0 allows the account to appear on the Welcome logon screen).

I've seen this used twice in the wild...once, it worked, and the second time, the bad guy had misspelled "SpecialAccounts", and as such, the functionality that they were trying to achieve wasn't realized.  Sometimes, a little attention to detail can go a long way.

There is malware that uses these Registry keys to keep new user accounts hidden from view on a live system, such as TrojanSpy:Win32/Ursnif , Trojan:Win32/Starter, and EyeStye.  As such, this plugin can provide indicators of a malware infection, an intrusion, or of malicious user intent on the system.  However, keep in mind, that this functionality can also be used for legitimate purposes, such as hiding an Administrator or HelpDesk account from view on the Welcome screen.

As of this writing, Corey Harrell and I are finishing updates to a number of plugins, and looking at merging plugins where appropriate.  As the information that we're looking for with the specaccts.pl plugin is beneath the Winlogon key, I've rolled the functionality into the winlogon.pl plugin, and retired the specaccts.pl plugin.

So, the functionality isn't going away...rather, it's going to be incorporated into an existing plugin.

Plugin: *_tln

If you've downloaded the new RegRipper plugins archive, you may have noticed several plugins whose names end in "_tln.pl".  These plugins specifically output their collected information in the five-field timeline (TLN) events file format that I use for creating timelines.

Many folks using the RegRipper tools may not be aware that you can use rip.exe to determine information about the plugins that you have currently have available.  For example, the following command will allow you to see all the plugins that you have, listed in a tabular format:

rip -l

This next command will allow you to see all of the plugins you have, listed in CSV format:

rip -l -c

This command will let you see all of the plugins that end in "*_tln", in CSV format:

rip -l -c | find "_tln"

Now that we have a list of the plugins that provide TLN output, we can easily include the output of the plugin in our timeline events file by using the following command:

rip -r path -p plugin  -u user -s server >> events.txt

An example of how this can be useful is in adding the UserAssist data for a specific user to the timeline events file...you can do that using the following command:

rip -r path -p userassist_tln -u user -s server >> events.txt

Very easy, very straightforward, and the use of these plugins can provide us with a good deal of granularity in our timeline.

Something that's very important to understand about the TLN plugins is that, in most cases, they will not display the same information as their accompanying plugin without "_tln" in the name.  In many cases, the information maintained in the keys and values extracted via the plugins is stored in a "most recently used" or "MRU" format, and as such, the LastWrite time of the key is associated with the most recent entry.  An example of this is the shellbags_tln.pl plugin...running this one side-by-side with the shellbags.pl plugin won't provide you with the same information, nor the same number of lines in the output.  However, this is by design...shellbag data is one of those "MRU" sources within the Registry.  One exception to this is the output of the userassist_tln.pl plugin; the time stamp data extracted by this plugin is stored in the binary content of the value data.

Typing the command to list the *_tln plugins will illustrate that most of the plugins appear to be oriented toward the NTUSER.DAT and Software hives.  The shellbags_tln.pl plugin was written to run against the USRCLASS.DAT hive, and lists its output based on the key LastWrite time or "MRU Time"; it does not list information in TLN format based on the created, last accessed or last modified times extracted from the shell items.  The samparse_tln.pl plugin will list information in TLN format based on various time stamps associated with each user account.  Also, with this plugin, you don't need to add the "-u" switch, as the user information is embedded within the hive file itself.

Plugin: Findexes

The findexes.pl plugin for RegRipper is a plugin that I wrote as a result of another analyst sharing his experiences on an engagement with me.  The analyst told me that he'd found some unusual references to Registry keys in malware code, which led him to determine that executable code was being stored in binary value data within the Registry.

This plugin can be run against any hive file.  What it does is traverse through all of the keys (so for larger hives, it can take a little bit of time to complete), looking for values with binary data.  When it finds binary data, it checks to see if that data includes "MZ".  Note that it does not look in a specific location, nor at offset 0...it uses a grep() statement to see if the data includes "MZ" at all.

When the plugin completes, you get a couple of pieces of information.  One is the count of values with binary data, along with the count of binary data with "MZ".  If there were any values found to contain "MZ", the key path, key LastWrite time, and value name are listed.

One System hive I ran the code against found 22660 binary values but none that contained "MZ".  A Software hive I ran the code against found 23190 binary values, one of which contained "MZ", and I got the key path and other data for that value.


Key: Microsoft\SystemCertificates\Disallowed\Certificates\471C949A8143DB5AD5CDF1C972864A2504FA23C9   LastWrite time: Mon Mar 28 21:26:31 2011
  Value: Blob  Length: 1751 bytes

Number of values w/ binary data types: 23190
Number of values w/ MZ in binary data:   1


It's pretty trivial to validate the information, in general, found by this plugin.  One way to do is to simply navigate to the key(s) in a viewer, and then look at the data.  Another is to add code to the plugin to dump the data out in a hex editor style view.

Now this plugin doesn't indicate that what it finds is a persistence mechanism; rather, it's used for data storage, so you might consider running it across any and all hives, including USRCLASS.DAT.  The process in which I tend to use this plugin is that I'll start by creating a timeline and if I see some unusual activity in the Registry during the time window during which the system seemed to be infected (i.e., Registry and file system data, *.idx metadata, etc.).  Given that the LastWrite time is only indicative of a change occurring to a Registry key, I might opt to run the plugin against hives from VSCs, rather than those within the system32\config folder, instead.

Overall, this plugin can be very useful.  The plugin can be added to profiles for every hive, or can be used for pivot point analysis when examining a timeline.

Plugin: EMDMgmt

Shortly after announcing the RegRipper consolidation, Corey hit me with a great idea...why not create a series of posts to spotlight a particular plugin, explain what it does, how it can be used, etc.  I thought that this was a great idea, and told him that I would join in, so you can expect to see posts from both of us every now and again, in which we discuss a specific plugin.  Once these posts start to appear, I will add them as links to a page on the RegRipper Wiki.  If anyone else decides to write a similar post, please send me the link and I'll add it to the page.

The first plugin that I thought I'd take a look at is emdmgmt.pl. "EMD" apparently stands for "external memory device", which was the working name of ReadyBoost while it was being developed.  When you connect a device to a Vista+ system, the ReadyBoost service checks the device to determine its characteristics and stores this information beneath the following key:

SOFTWARE\Microsoft\Windows NT\CurrentVersion\Emdmgmt

This key gets populated with subkeys that refer not just to thumb drives connected to the system, but also external drives, sometimes referred to as "drive enclosures" (which, of course, has to have a drive in it).  It appears that ReadyBoost performs some sort of "check" of the device in order to determine it's capabilities and see if it's suitable for use.

This plugin is useful for two primary reasons.  First, it's a great way to verify that certain types of devices (thumb drives, external drives) had been connected to the system at one point.  This can be validated against other sources of information (System hive, etc.).

The other useful aspect of information stored in this key applies specifically to thumb drives.  In particular, the subkey that applies to a thumb drive contains the device class identifier, the device serial number, the volume serial number, and possibly the volume name (if the mounted volume has a name).  For example,

Disk&Ven_Best_Buy&Prod_Geek_Squad_U3&Rev_6.15
  LastWrite: Sun Jul 17 12:13:25 2011 Z
  SN: 0C90195032E36889&0
  Vol Name: TEST
  VSN: 6403-CD1C

This is clearly a Best Buy Geek Squad U3 thumb drive that I connected to my system.  That I really like about this is the volume serial number that's listed in the output.  This is translated from the information maintained at the very end of the key name.  I've used this information to correlate to VSNs stored in Windows shortcut/LNK streams (shortcuts in the user's Recent folder, Jump Lists), allowing me to tie the various artifacts together in order to demonstrate not only that a particular user accessed the thumb drive, but to also demonstrate what the file system on that device looked like at the time that the user accessed it.  I can then further augment this information with the output of the comdlg32.pl and shellbags.pl plugins.

RegRipper Consolidation

RegRipper has been consolidated at a single, static site.

Going forward, everything related to RegRipper will be available via (either at, or linked from) this one site.  Updates to the tools will be available here, documentation will be available in the Wiki, and the latest plugin archives will be available from this site, as well.

The reason for doing this is that there just seems to be too much confusion associated with the tool.  I've received emails saying that there are just too many sites that offer RegRipper, and that it's too confusing to figure out which one is the right one.  So, let's just make it simple...this is the right one.

You'll notice that there's material in the Wiki, as well.  We'll be using this to document and provide information in one single, static location.  There is some information there now, but if there's something of interest that you can't find, let me know. I'll be happy to add or update information on the Wiki so that it's more useful.

I greatly appreciate all of the work that folks like Francesco, Brett, and Corey have put into the tool over the years.  I also greatly appreciate the work of folks who have written plugins, as well as folks like Adam and "Cheeky4n6Monkey" who've written tools in an effort to make RegRipper easier to use.  This consolidation does not take away from the great work that they've all done...it's simply a desire to bring everything together in one place.

So, what's different with this iteration of RegRipper?  Not a lot, really.  Again, it's more of a consolidation than anything else.  Corey and I have put a lot of effort into "cleaning" up the plugin archive.  We have updated a number of the plugins, consolidating some functionality, and adding other functionality (support for Wow6432Node where appropriate, etc.); in fact, there are so many of those little changes that we're going to forego the History page, but we'll pick it back up as we start documenting changes again going forward.  So really...the biggest change is just the consolidation of everything in a single location.

Again, going forward, I'd like to have everything related to RegRipper at one site.  Also, if you have any plugin requests, or just want to provide sample data for testing, please feel free to send it to me.

Finally, one more great big thanks to all of those who have supported RegRipper, by blogging about it, requesting or providing plugins, including it in an archive or distro, etc. 

There Are Four Lights: Malware Indicators in the Registry

It can be extremely beneficial to understand various artifacts that malware creates on a system, particularly in light of the fact that AV isn't catching everything.  Most AV appears to look for and then scan across executable files...some AV does find indicators based on text-based data, such as JavaScript code, etc.

Not all malware uses the Registry for persistence.  For example, Theola uses a Chrome plugin to perform bank fraud, and W32/Crimea modifies imm32.dll in order to remain persistent (I found this variant in 2010; this is a write-up from another variant from 2007).

Not all malware creates really obvious indicators in the Registry, either.  Corey talked about indicators for a variant of ZeroAccess.  However, I analyzed a system that had been infected with another variant of ZA, one that created the HKCU\Software\Microsoft\Windows\CurrentVersion\Ext\Settings\{8AD9C840-044E-11D1-B3E9-00805F499D93} key, the effect of which is explained in this GreyHatHacker blog post.  While this isn't a persistence mechanism, it does illustrate an indicator of a malware infection.

"Detecting" Persistence Mechanisms
There was a SANS webcast in January 2012 titled Detecting Persistence Mechanisms, during which a number of persistence mechanisms were mentioned, including several found in the Registry.  However, something that wasn't mentioned was how to actually go about detecting persistence mechanisms being created by malware.  Corey recently published an excellent blog post titled, Tracking Down Persistence Mechanisms, which does a great job of illustrating how easy it is to quickly examine the contents of autostart (or "ASEP") locations, particularly in the Registry.

The process I use to detect the use of Registry persistence mechanisms and other malware artifacts is to start by adding the key LastWrite times from the Registry hives (both NTUSER.DAT and USRCLASS.DAT for users) to my timeline.  This is exactly how I found the ZeroAccess artifact I described earlier in this blog post...the modified key was right there in the timeline.  I even went so far as to examine the hive file extracted from a VSC created just prior to the LastWrite time of the key, and I was able to determine that the LastWrite time was, in fact, when the key was created (i.e., the key didn't exist in the hive file from the VSC).  Timelines are a fantastic way to add context to the data that you're looking at, as well as to increase your relative level of confidence in the validity of that data.  However, timeline analysis is best utilized as part of an overall analysis plan, developing pivot points and items of interest via other data retrieval and analysis mechanisms.

Once I find an interesting Registry artifact in close proximity to other activity on the system that is associated with the malware, I have a number of options available to me.  Many times, I will open the hive in a viewer and take a look at what information is contained in the key itself...examine the subkeys, values and data.  I can correlate this with information gleaned from online searches, and very often, quickly write a new or modify an existing RegRipper plugin.  I then ensure that the Registry artifact is included as part of my shortened view of the overall timeline, along with a clear description of why it's significant, along with supporting documentation and references.  This serves the purpose of not only providing information to my customer, but also documenting the information for my own use.  In most cases, this entire process covers a span of a couple of minutes, maybe up to an hour depending up how much information is out there and available.

When Does It Start, and Why Does It Matter?
Where within the system that malware creates it's persistence mechanism has significant impact on your investigation, in part because investigations no longer center around the question of "was the system infected?" 

Take a look at this ThreatExpert report; the report points to a Registry value within the user hive that the malware adds data to in order to remain persistent, and then states:

...so that %AppData%\skype.dat runs every time Windows starts

IMHO, this can be easily misinterpreted.  If the analyst assumes that "Windows" refers to the system, then the statement is incorrect.  However, if "Windows" refers to the shell, then it is correct...but to a point.  In this case, the malware will start the next time that user logs into the system, and the Windows Explorer shell starts for that user. 

Ok...but so what?  Well, this can be a very important distinction to make.  For example, let's say that someone from the helpdesk logs into an account on a user's workstation in order to assist with or fix something.  They go to a web site to download a patch or update, and while it's installing, they do a bit of surfing...and the system gets infected.  If the malware infects the system within the context of only that user account (i.e., creates a Registry persistence mechanism in the "HKCU" hive), then that malware will not be launched again until that user account is used to log into that system again.  Where this distinction is important is in cases of the "Trojan Defense" (was the system infected, and did the malware execute?), as well as PCI forensic audits, where the PCI Council requires the analyst to identify the "window of compromise" in a dashboard area of the report.  For merchants that know about how many credit card transactions they have in a given time period, that "window of compromise" can have a significant effect on the overall outcome of the report, potential fines levied by the council, etc.  I examined a system once where the malware was identified and deleted by an on-demand AV scan less than 48 hrs after it was created on the system, and the intruder didn't upload a new version of the malware (albeit with the same name) for 6 weeks...which, like I said, had a significant impact on the overall outcome of the investigation.

In another example, I've seen a server systems that were infected with malware when an administrator logged in and performed some series of activities (usually web surfing or checking email...hey, it happens...) that led to the infection, with the persistence mechanism for the malware being in the Administrator user's NTUSER.DAT.  When the server is rebooted, the malware doesn't persist and begin running again until the user logs into that account...in some cases, depending upon the server, that could be for several days or weeks.  Once again, this is a very important distinction to make.

The ThreatExpert report mentioned above is only an example...it isn't the only site where these sorts of messages can be seen.  I've seen reports at the MMPC site that state that malware creates a persistence mechanism in the HKCU\..\Run key so that it "starts whenever the system starts".  The same is true for a number of reports at AV vendor sites.

Wow6432Node
I discussed Wow6432Node in a previous blog post, and Corey has discussed this as well. And yes, it is very important to point out yet again.  And again.  And again.  Why is that?  Because I honestly believe that most analysts are missing this source of data.

Links

New HEFCBlog book is out!
David Cowen posted that his new book is out!  The book is titled, Computer Forensics InfoSec Pro Guide (Beginner's Guide).  David's also got a new web site to go along with the book...learndfir.com.  There isn't a great deal of information available about this book or its contents yet, but Dave has always been a fount of great things for DFIR, so keep your eyes on the site.  David did state on his blog that he's working on some "links, documents, and forensic images", so look for good things to come.

If you're going to get David's book, I would recommend that you also consider Brett Shaver's book, Putting the Suspect Behind the Keyboard, which provides an investigator's perspective and insight into determining who was sitting at the keyboard.

CyberThreat Detection
Lesley Carhart posted this article over on the Motorola Solutions Community site, mentioning the need for log monitoring, particularly in the face of Mandiant's APT1 report.  A lot of what Lesley says in the post has been mentioned before, but I tend to think that it's important to keep the same message consistent and repeated...just look around and see all of the organizations that get hit and don't have any of what she mentions implemented.

One statement made in the article that caught my attention was:

Attackers frequently spread laterally, system to system, using legitimate accounts and services. Would your organization detect this?

The reason this caught my attention was that as far back as I can remember, even going back to the 2012 DoD CyberCrime Conference, one of the primary complaints about the mention of "lateral movement" is that there is a dearth of information regarding what that looks like...so, how would an organization be able to detect this sort of activity if the folks who know what it looks like aren't sharing the information?  This was the case at DC3 2012...I heard a couple of attendees lamenting the fact that for all of the presentations that included "APT" in the title, none of them actually provided actionable information.  I can only say that I attended three of those presentations, and not one of the authors actually listed what that lateral movement within the infrastructure looks like to an analyst.

Using RegRipper
Ken posted the Work Smarter, Not Harder article to his blog this weekend, which, in part, raises awareness of how to make the most effectively use of RegRipper.  In his post, Ken discusses using some basic functionality of RegRipper...creating custom profiles...and ties that to another recent blog post.  I greatly appreciate the time that Ken took to not only use the tool, but to write about his experience and use of the tool...I think that this really validates how easy-to-use these tools can be, and how effective their use can be in pursuing an examination.  It's one thing for me to write about how to use the tool, it's something else entirely for someone like Ken to share a real-world example of how he used the tool to complete analysis.

One thing that Ken says in the post is:

Running rip.exe -r ntuser.dat -f ntuser-all, for example, will run every ntuser.dat specific plugin against the ntuser.dat file.

A bit of clarification is required here...the command will run every "ntuser.dat-specific plugin listed in the ntuser-all profile against the ntuser.dat file".  My point is that analysts should not assume that every plugin intended to be run against the NTUSER.DAT file is listed in the ntuser-all profile.  This file is a flat text file, with no extension (which simply means that it does not end in ".txt" or ".dat", or...anything) that contains a list of plugins that you'd like to run, in the order that you'd like to run them.  It's always good to check and ensure that the plugins you want to be included in the profile are actually listed.  If not, they're very easy to add, as Ken described in his post.

My own custom RegRipper profile for retrieving program execution artifacts from the NTUSER.DAT hive includes the following plugins:

userassist
sysinternals
compatassist
applets
autorun
muicache
runmru

As many folks are aware, I teach a couple of courses.  During the courses, I invariably meet people who "use" RegRipper on a regular basis...what this most often amounts to is downloading RegRipper v2.5 (if you watched the SANS webcast from January 2013 closely, you could see that Mandiant is still on v2.02...) and simply running the UI version of RegRipper.  But there's so much more available through the tool, as Ken described in his post.

For example, I get asked, "...is there a list of available plugins?" on a regular basis.  This is why I provided a very simple facility through rip.exe to output a list of plugins (described in this blog post), including an option for CSV output.  An example of a command line that I discuss in the courses, for providing just a list of plugins that retrieve information from the NTUSER.DAT hive is:

C:\tools>rip -l -c | find ",NTUSER,DAT," /i > ntuser.csv

Run this command, and then open the resulting .csv file in Excel for easy review.  An alternative would be to simply drop the "find" portion of the command, open the resulting .csv file in Excel, and then sort of the third column to list the plugins based on the hive file.

You can also take this same approach to create specific profiles for USB device tracking within various hives, as well.

Side Note: One question is regularly ask users of RegRipper is, what would make RegRipper a 'better' tool. More/better documentation?  Some additional functionality?  If there's a specific plugin that you'd like to see created, you can take a look at Adam's 3RPG site (he blogged about creating four RR plugins in 15 min.), or you can contact me and request the plugin - all I'll need is a concise description of what you're looking for, and some sample data.  If you provide this information, I'm able to get plugins turned around rather quickly.  There is a LOT of information out there embedded in Registry hive files, and relying on a small group of people to create the plugins, when we're not seeing this information, amounts to a significant loss for the community.

"Cyber" Insurance
Something I've been watching with a bit of fascination is the spread of "cyber" insurance.  Looking back over the response and analysis engagements that I've performed or been involved with over the years, including PCI forensic audits, this is a very interesting development.  You'd need to review the annual reports from companies such as Mandiant, Trustwave and Verizon to see the effect that compliance regulations have had on organizations getting compromised...based on previous year's reports, one might think that there hasn't been much of an effect.

What's clear is that the issue of organizations getting "hacked" is getting even more attention.

CyberGuardians post
I did not attend the SANS Cyber Thread Intelligence Summit 2013, but I did get to read about it at the CyberGuardians blog.  Having been engaged in DFIR work for some time, I thought that both the presentations and the reviews of them were very insightful, and that the focus of DFIR work was moving in the right direction.  So many times as an emergency responder, I would show up and find that the on-site IR team was completely hamstrung, with no ability to get any sort of meaningful information during an incident.  In many cases, even the most basic information needed to simply assess systems had to be requested from network or systems ops folks...this was true not only at commercial and private sector sites, but also within the federal government.

What I really took away from the post is the realization that a mainstream organization such as SANS is now espousing the need for organizations to not only effectively consume (i.e., make use of) threat intelligence, but to also produce and share threat intelligence, as well. A number of consulting organizations offer this as a service, but some of them focus solely on one are of the IR spectrum (i.e., network sources, and not bringing memory- or host-based artifacts into the equation).  Part of the problem with this is that, while these are excellent services, many of the potential consumers of this intelligence are simply neither prepared nor equipped to make effective use of this information.

ImDisk
A new version of the ImDisk Toolkit is available, which works on Windows up to Win8 (32- and 64-bit).

Training
There are still seats available for the 9-10 April offering of Timeline Analysis at our Reston location, as well as for the Windows Forensic and Registry Analysis course combo to be held at the Santa Cruz PD training facility.  If you're interested in any of these courses, but cannot make it to the Reston location, contact us about sponsoring the training at your location.

There are Four Lights: Program Execution

I'd seen a tweet recently where someone was asking about information regarding the last time a user launched an application on a system. The system had an SSD drive, and as such, application Prefetching was disabled, by default.  Therefore, one of the more well-known artifacts that indicate program execution was not available to the analyst.  The fact is that there are a number of locations available on Windows systems that will maintain indications of program execution.  Although not all of them allow the program execution or application launch to be tied directly to a user, or to be correlated to a specific time, they may be useful, nonetheless.

A valuable aspect of these locations is that they will very often persist beyond the deletion or removal of the application.

This category of artifacts can assist you in implementing an analysis matrix for your examination.

This post will be directed at providing information about artifacts that provide indications of program execution; many of the artifacts listed will not be able to allow the analyst to state explicitly that a user last launched an application at a specific date and time; rather, analysts should be aware of the artifacts, and be able to apply them (and others) as needed.  These artifacts can be used in a number of cases, in order to demonstrate a window of compromise, malware detection (just because you detected malware, does that mean that it actually ran??), etc.

Application Prefetch Files
Application prefetch files are a great source of information about applications run on the system, as well as when they were last run (although they are not specific to a user).  However, Windows server systems do not have application prefetching enabled by default, and application prefetching is disabled by default when Windows sees that it's being run from an SSD drive.

Shortcut/LNK files and Jump Lists
I include shortcut/LNK files and Jump Lists together because Jump Lists are comprised of LNK streams (this goes back to my post on understanding data structures).  And they can both provide indications of program execution (as well as access to remote storage).  In order to determine which application was launched, you may need to do some file extension analysis, or in the case of Jump Lists, start with an AppID lookup.

Browser History
With the exception of what was described in this blog post, the existence of a browser history will demonstrate the browser had been launched, within the context of a specific user.  In most cases, the specific records requested will include time stamps.  Also, don't forget to check things like bookmarks/favorites, etc., which will provide other indications of the use of the browser, even after the browser history has been cleared or trimmed (most browsers have an automatic process for clearing out older history and cache entries, independent of the user specifically performing the action).  Also, for IE, check out the RegRipper menuorder.pl plugin.

Hibernation Files
While hibernation files will not explicitly put the suspect at the keyboard, much like crash dump files, they can be used to demonstrate that an application was (or wasn't) running at one time.  If you're going to analyze hibernation files, I strongly recommend that you consider using Volatility, or take the course taught by these folks.

Windows Event Log
I was analyzing a Windows 2008 R2 server not long ago, and found that an intruder had installed and run Havij and some other, similar tools.  Interesting enough, the Application Experience Event Log included entries indicating that the application had been installed on, as well as removed from the system.  Remember, Process Tracking isn't always enabled within audit configuration, but there may be other ways to determine indications of applications or programs being executed via serivces starting (event ID 7035/7036), etc.

Registry
The Windows Registry can contain a number of interesting keys and values that can provide indications of applicaitons being launched, or programs being executed.  In many cases, much like the file system, these locations can contain information about program execution long after the deletion/removal of the application or program.

MSIs
Windows maintains a list of applications that were installed via Microsoft Installer (*.msi) files.  While this does not tie directly the execution of the program, it can indicate that it was installed.

RecentDocs
The user's RecentDocs key can provide indications of program execution, even if indirectly.  For example, an .exe file may have been opened, but rather than launched, the user had opened it in a hex editor...which itself is an indication of "program execution" (of the hex editor).  You may have to perform file extension analysis or timeline analysis in order to determine specifically which application was used to open the file.

Also, be sure to check the OpenSaveMRU and OpenSavePidlMRU subkeys beneath the ComDlg32 key.

AppCompatCache
An old favorite, Corey Harrell has talked about this Registry value on his blog.  Also, if you really want to get  the available information about this value, check out what Mandiant has to say about it.  They discovered and publicized it, and even wrote up an excellent white paper on parsing the value data.  It's important to keep in mind that the last modification time for each application that is retrieved by the various tools is from the file system.

MUICache
I've found over the years that some applications run within the user context have had entries created as values beneath this Registry key.  Now, the values do not have a time stamp associated with them

*Tracing
MS states that the Routing and Remote Access protocol has some pretty extensive tracing capabilities used for troubleshooting.  During exams, I've seen applications with networking capabilities included in subkeys beneath this key.

*DirectDraw, etc.
There are a number of subkeys beneath the Microsoft key (in the Software and NTUSER.DAT hives) that have names like DirectDraw, Direct3D, etc., and some of these may have a subkey named MostRecentApplication, which provides the name of the last application to make use of the capability.  I have seen this most often used by legitimate applications, such as iexplorer.exe, but it may also lead to malware (see this Sophos ZBot writeup). 

SysInternals
While this key is particular to a specific set of applications, the fact is that in order to run the SysInternals utilities, you need to accept the EULA, which creates a Registry subkey beneath the SysInternals key.  This can be very useful during an exam.

AppCompatFlags (NTUSER.DAT)
This key contains artifacts of applications executed by a user under the Program Compatibility Assistant, even if no compatibility modes are applied.

UserAssist
These artifacts provide indications of applications that the user launched by clicking on them through the shell, either double-clicking an icon on their Desktop or through Windows Explorer, or by selecting the Start button and clicking on the application through the program menu.

RunMRU
This Registry key provides indications of commands that the user has typed in at the Start->Run box.

AutoStart locations - *Run keys, Windows Services, etc.
You would need to correlate these entries to when the system was started, or when the user logged in.  This can be extremely significant.  If something (malware or another application) is set to autostart based on when a user logs in (usually found within the HKCU hive), then the last time that the application executed could be well after the system was started.  This may not be significant to the examination, but it does go to overall clarity and correctness of your findings.

LANDesk
I've seen a couple of instances where a system I was examining had LANDesk installed; part of the functionality of LANDesk includes the application writing Registry keys for each application launched on the system, including values for when the application was first and last launched, the user account used to launch the application the last time it was run, etc.  This proved very useful, particularly when included in a timeline.

Windows Services/AutoStart Locations
Windows Services can provide some excellent information regarding the start of an application; however, do not assume that because a service is listed that it automatically started with the system booted.  This is not always the case.  An analyst needs to check the start type of the service, as well as check the Windows Event Log for events with ID 7035/7036 (indicate a service start).  Another artifact that can be extremely useful when examining services is the Enum\Root\LEGACY_* keys within the System hive; the subkeys beneath these keys for each service are created the first and last time, respectively, that the service was run, and like other artifacts, will persist after the service was either disabled or removed from the system.

The same is true with other autostart locations; you need to be clear on the location and the effect that it has on the application start...even MS has gotten this one wrong.  If the application is listed in a user hive (HKCU), then it will start when the user logs in, NOT when the system starts.

'*' indicates Registry keys that may also have a counterpart found in the Wow6432Node path.

The artifacts described in this blog post are intended to assist analysts in understanding where to look for indications that applications has been run on a system.  In some cases, the artifacts may tie the program execution to a specific user, and other times, to a specific time.  These artifacts are not specific to malware...in fact, I tend to attribute other, specific artifacts to the "malware" artifact category.  Other artifacts may be specific to applications...for example, the Terminal Services Client will maintain a list of systems to which a user has connected in both Jump Lists, as well as beneath a Registry key in the NTUSER.DAT hive, indicating that the user launched the application.  IE (versions 5-9) has Registry artifacts, as well.  Applications that include MRU lists will allow the analyst to demonstrate the use of that application, by a user, at a specific time.

Resources
Network artifacts found in the Registry

BinMode: IE Index.dat

I've posted on the need for analysts to understand data structures before, and I recently conducted some analysis that I think illustrates this point extremely well.

The purpose of this blog post is to illustrate how certain artifacts can be used to detect the presence of malware on a system.  While a tool for doing so is described, this is not a blog post about parsing histories for all of the browsers a user may or could have used, in part because the artifacts examined do not pertain to other browsers.

Not long ago, I tweeted that I'd written a plugin for the Forensic Scanner that gets statistics from IE (version 5 - 9) index.dat browser history files for all user profiles on the system.  Almost immediately, someone tweeted asking, "what if the user isn't using IE?"  That's a good question, but it misses the point of the analysis technique and of having the plugin in the first place.

I was analyzing a system recently that had been infected with ZeroAccess (see the Sophos report), and one of the things I was aware of the malware was capable of doing was click-fraud.  In my analysis, I saw that the malware used an autostart persistence mechanism that was outside the scope of the user context...my timeline illustrated the artifacts being created.  Knowing that much of the malware that communicates off-system will use the WinInet API functions to do so, I began looking at the index.dat files for the various user profiles available on the system.  What I found was that the NetworkService account had much more significant "browser history" than the 'normal' user account on the system.

That's exactly right...there's no typo.  The NetworkService account.  How could that be?  That's not something you see very often, is it?  I mean, how does someone sit down at the keyboard and log into the account, and launch IE?  The answer is...they don't.  What happens is that when code using the WinInet API is run at privileges other than those of a user, the artifacts are created in another account profile.  For example, back when Windows XP was more prevalent in my analysis lab, I would see systems on which the Default User profile had a populated index.dat file.  I've seen the same thing with the LocalService account; this may depend upon which process the malware is injected into, and where that process falls in the svchost.exe hierarchy.

So my point is that for malware detection, checking all user accounts for statistics regarding their index.dat files might be a good idea.  Once you understand the data structures in question - that is, the headers of the index.dat file, which, thanks to Joachim Metz, are well documented - this becomes a trivial task.

I started by writing a simple script that would parse the contents of the header of the index.dat file and tell me a little bit about what I could expect to see.  Based on the format specification for the file, I was interested in things like the offset to the HASH table, as well as the directories beneath the "Temporary Internet Files\Content.IE5" folder and the number of cache files in each folder.  This information is stored in the headers of the files, and is very easy to parse out and display.  I got the script working and it proved to be very useful.  However, I know that there's a process to using the script...I have to determine which user profiles are available, determine the version of Windows being examined, and based on those two pieces of information, type in the appropriate path to the index.dat file in question.  By hand.  Seriously?

So, I created a system class plugin for the Forensic Scanner to do all of this for me.  Automatically.  System class plugins are run against the entire system, whereas user class plugins are run against each user profile selected by the analyst.  Based on the specific artifacts that I'm looking for, a system class plugin is exactly what I need.

What follows is an excerpt of the output from the ie_stats.pl plugin.  First, the Administrator account profile:


g:\Documents and Settings\Administrator\Local Settings\Temporary Internet Files\Content.IE5\index.dat
File size              : 163840
Hash Table Offset      : 0x5000
Number of blocks       : 1152
Number of alloc. blocks: 1089

Dir: LPVS8JVQ  Files: 90
Dir: IR1PLUTE  Files: 89
Dir: 5K3JMTA3  Files: 88
Dir: O3VB95DY  Files: 89


As you can see, the Administrator account has some browser history associated with it.  The hash table is located at offset 0x5000 within the index.dat file, and there are four subdirectories, each containing a number of cache files.


g:\Documents and Settings\Default User\Local Settings\Temporary Internet Files\Content.IE5\index.dat
File size              : 32768
Hash Table Offset      : 0x0
Number of blocks       : 128
Number of alloc. blocks: 32

Dir: O8WMK2SC  Files: 0
Dir: UAAUTN4C  Files: 0
Dir: Q323MBYB  Files: 0
Dir: 4VRPMD81  Files: 0


Okay, so this is what an empty index.dat looks like; the Default User profile has no IE history associated with it...there is no hash table, and the subdirectories don't contain any files.


g:\Documents and Settings\NetworkService\Local Settings\Temporary Internet Files\Content.IE5\index.dat
File size              : 9437184
Hash Table Offset      : 0x5000
Number of blocks       : 73600
Number of alloc. blocks: 58784

Dir: EIQLTWH3  Files: 384
Dir: KFSPU8SK  Files: 384
Dir: ABR75H1M  Files: 384
Dir: 5QI7EWW7  Files: 384
Dir: TTYX5IX2  Files: 384
Dir: 5GDCH3XG  Files: 383
Dir: KZZXKXWH  Files: 383
Dir: LA2SZ5HL  Files: 383
Dir: TLRE11UL  Files: 383
Dir: IYT9OTGD  Files: 383
Dir: 58I9EM25  Files: 383

....

The NetworkService account was the one that set off alarms!  As you can see, this profile has a significant history!  Parsing the actual index.dat file and displaying the entries in a micro-timeline (just the URL records) illustrated a significant amount of activity in a relatively short amount of time, with more URLs being requested per second than most users are capable of typing in or clicking via the browser.

In this case, I used the command line version of the Forensic Scanner to run a single plugin.  I had mounted the image file via FTK Imager, and it appeared on my system as the G:\ volume.  I then typed the following command:

C:\Perl\scanner>fscan.pl -s g:\windows\system32 -p ie_stats

That's all it took.  Again, this is NOT a comprehensive analysis...this is a quick check to see if I could expect any potential issues.  Another way to run this would be to select the "malware" artifact category...the ie_stats.pl plugin is included in that category.  Also, the purpose of running this plugin is NOT to find indications of browser activity, for all browsers, and for all users.  Instead, the purpose of this plugin is to check for something very specific...it does so automatically, accurately, and very, very quickly.  This entire exercise took only a couple of minutes, most of which was spent mounting the image file...once that was done, the plugin ran very quickly, and provided me with the information I needed.  I don't want to list all of the URL and REDR records from the NetworkService profile index.dat because just from what we see above (not all of the directories are listed) there are around 4000 or so files in the cache subdirectories.

Again, the purpose of this blog post is to illustrate an analysis technique.  In the past, what I've done is to use ProDiscover to populate the "Internet History View" from within the image, and look for indications of service accounts with URL records in their index.dat.  However, the methodology used by ProDiscover is more comprehensive...it searches the entire file system, and parses all of the records out of each index.dat file that it finds.  In this case, that's much more than what I'm looking for.

This analysis technique can be combined with other tools into a more comprehensive process, as described in this blog post.  Parsing application prefetch (*.pf) files and finding indications of wininet.dll as one of the loaded modules might be something to correlate with this analysis technique.

Resources
Rob Hensing's post on the Default User with an IE browser history
ForensicsWiki page: IE History File Format
Extremely relevant post from Hogfly (2007)