A Smattering of Links and Other Stuff

Registry

Well, 2014 ended with just one submission for the WRA 2/e Contest.  That's unfortunate, but it doesn't alter my effort in updating the book in any way.  For me, this book will be something to look forward to in 2015, and something I'm pretty excited about, in part because I'll be presenting more information about the analysis processes I've been using, processes that have led to some pretty interesting findings regarding various incidents and malware.

In other Registry news, Eric Zimmerman has created an offline Registry parser (in C#) and posted it to GitHub.  Along with Eric's Shellbag Explorer tool, it really seems as if his interest in the Windows Registry is burgeoning, which is great.  Hopefully, this will generate some of the same interest in others.

Tools
Willi has a new tool available called process-forest, which parses event ID 4688 records within the Security.evtx file to develop a process tree.  If you have the necessary auditing enabled, and have increased the default size of your Security Event Log, this tool will provide you with some great data!

Tool Updates
Speaking of the Registry, I've made some updates to several of my tools.  One was to extend the inprocserver.pl plugin by creating a RegRipper plugin (fileless.pl) that could be used to scan any hive file for indications of "fileless" malware, such as Phasebot or Poweliks.  My testing of this plugin was limited, but it works for other search criteria.

I've also made some minor updates to other tools.

Widening the Aperture through Sharing
I was doing some reading recently regarding attribution as a result of DFIR analysis, which included Richard's recent post. From there, I followed the link to Rid and Buchanan paper (PDF), which was fascinating reading.  I took a lot of what I read and applied it to my thinking on threat intel in general, and not just to attribution.  One of the things I've been noodling over is how to widen the aperture on the indicators that we initially collect/have access to, and how that relates to the incident response process.

One of the big things that immediately jumped into my head was "sharing".

Secureworks Research Blog post
Speaking of sharing, this article (titled "Sleeper Agents") was published recently on the Dell Secureworks Research Blog.  It's a great example of something seen in the wild, and

Sharing Indicators
Continuing with the sharing theme, @binaryz0ne posted an article to his blog regarding artifacts of user account creation, looking at differences between the use of the command line and GUI for creating local accounts on a system (i.e., not AD accounts).

A couple of things to point out...

First, this testing is for account creation.  The accounts are being created, but profiles are not created until someone logs in using the credentials, as mentioned by Azeem.

Second, if you were interested in just account creation information, then collecting ALL available timeline information might be time consuming.  Let's say you found the event log record for account creation and wanted to focus on just that aspect of analysis.  Using the "Sniper Forensics" principles, you could create a timeline from just the Windows Event Logs (Security, LocalSessionManager, RemoteConnectionManager, maybe even TaskScheduler, just in case...), the SAM Registry hive (samparse_tln.pl RegRipper plugin), prefetch files (if available), and the user's (account collected from Windows Event Log record) NTUSER.DAT and USRCLASS.DAT.

I've seen instances of both (use of CLI and GUI to create accounts...) in the wild, and it's great to see someone putting in the effort to not only test something like this, but to also share their findings.  Thanks, Ali!

I've been doing some testing of Powershell, and have been using a .ps1 file to create a user and add it to the local Administrators group, and finding some truly fascinating artifacts.

Python
One of the things I've been working on (well, working off and on...) is learning to program in Python.  I do plan to maintain my Perl programming, but learning Python is one of those things I've laid out as a goal for myself.  I've already written one small program (destlist.py) that I do use quite often for parsing the DestList streams out of automaticDestination Jump Lists, including adding that information to a timeline.  I don't expect to become an expert programmer, but I want to become more proficient, and the best way to do that is to start developing projects.

Not long ago, I was doing some reading and ran across this ISC post that mentions the impacket library (from CoreLabs), and I thought that was pretty interesting.  Not long after, I was reading Jon Glass's blog and ran across another mention of the impacket library, and solutions Jon has been looking at for parsing the IE10+ WebCacheV01.dat history database (part 3 of which can be found here).  I've been pretty successful using the NirSoft ESE Database Viewer so far, but like Jon, I may reach the point where I'd like to have something that I can extend, or better yet, provide output in a format that I can easily incorporate into my analysis processes.

What It Looks Like: Disassembling A Malicious Document

I recently analyzed a malicious document, by opening it on a virtual machine; this was intended to simulate a user opening the document, and the purpose was to determine and document artifacts associated with the system being infected.  This dynamic analysis was based on the original analysis posted by Ronnie from PhishMe.com, using a copy of the document that Ronnie graciously provided.

After I had completed the previous analysis, I wanted to take a closer look at the document itself, so I disassembled the document into it's component parts.  After doing so, I looked around on the Internet to see if there was anything available that would let me take this analysis further.  While I found tools that would help me with other document formats, I didn't find a great deal that would help me this particular format.  As such, I decided to share what I'd done and learned.

The first step was to open the file, but not via MS Word...we already know what happens if we do that.  Even though the document ends with the ".doc" extension, a quick look at the document with a hex editor shows us that it's format is that of the newer MS Office document format; i.e., compressed XML.  As such, the first step is to open the file using a compression utility, such as 7Zip, as illustrated in figure 1.

Figure 1: Document open in 7Zip

As you can see in figure 1, we now have something of a file system-style listing that will allow us to traverse through the core contents of the document, without actually having to launch the file.  The easiest way to do this is to simply extract the contents visible in 7Zip to the file system.

Many of the files contained in the exported/extracted document contents are XML files, which can be easily viewed using viewers such as Notepad++.  Figure 2 illustrates partial contents for the file "docProps/app.XML".

Figure 2: XML contents

Within the "word" folder, we see a number of files including vbaData.xml and vbaProject.bin.  If you remember from PhishMe.com blog post about the document,  there was mention of the string 'vbaProject.bin', and the Yara rule at the end of the post included a reference to the string “word/_rels/vbaProject.bin”.  Within the "word/_rels" folder, there are two files...vbaProject.bin.rels and document.xml.rels...both of which are XML-format files.  These documents describe object relationships within the overall document file, and of the two, documents.xml.rels is perhaps the most interesting, as it contains references to image files (specifically, "media/image1.jpg" and "media/image2.jpg").  Locating those images, we can see that they're the actual blurred images that appear in the document, and that there are no other image files within the extracted file system.  This supports our finding that clicking the "Enable Content" button in MS Word did nothing to make the blurred documents readable.

Opening the word/vbaProject.bin file in a hex editor, we can see from the 'magic number' that the file is a structured storage, or OLE, file format.  The 'magic number' is illustrated in figure 3.

Figure 3: vbaProject.bin file header

Knowing the format of the file, we can use the MiTeC Structured Storage Viewer tool to open this file and view the contents (directories, streams), as illustrated in figure 4.

Figure 4: vbaProject

Figure 5 illustrates another view of the file contents, providing time stamp information from the "VBA" folder.

Figure 5: Time stamp information

Remember that the original PhishMe.com write-up regarding the file stated that the document had originally been seen on 11 Dec 2014.  This information can be combined with other time stamp information in order to develop an "intel picture" around the infection itself.  For example, according to VirusTotal, the malicious .exe file that was downloaded by this document was first seen by VT on 12 Dec 2014.  The embedded PE compile time for the file is 19 June 1992.  While time stamps embedded within the document itself, as well as the PE compile time for the 'msgss.exe' file may be trivial to modify and obfuscate, looking at the overall wealth of information provides analysts with a much better view of the file and its distribution, than does viewing any single time stamp in isolation.

If we continue navigating through the structure of the document, and go to the VBA\ThisDocument stream (seen in figure 4), we will see references to the files (batch file, Visual Basic script, and Powershell script) that were created within the file system on the infected system.

Summary
My goal in this analysis was to see what else I could learn about this infection by disassembling the malicious document itself.  My hope is that the process discussed in this post will serve as an initial roadmap for other analysts, and be extended in the future.

Tools Used
7Zip
Notepad++
Hex Editor (UltraEdit)
MiTeC Structured Storage Viewer

Resources
Lenny Zeltser's blog - Analyzing Malicious Documents Cheat Sheet
Virus Bulletin presentation (from 2009)
Kahu Security blog post - Dissecting a Malicious Word document
Document-Analyzer.net - upload documents for analysis
Python OLETools from Decalage
Trace Evidence Blog: Analyzing Weaponized RTF Documents

Addendum 6 Jan 2015 - Extracting the macro
I received a tip on Twitter from @JPoForenso to take a look at Didier Stevens' tools zipdump.py and oledump.py, as a means for extracting the macro from the malicious document.  I first tried oledump.py by itself, and that didn't work, so I started looking around for some hints on how to use the tools together.  I eventually found a tweet from Didier that had illustrated how to use these two tools together.  From there, I was able to extract the macro from within the malicious file.  Below are the steps I followed in sequence to achieve the goal of extracting the macro.

1. "C:\Python27>zipdump.py d:\tips\file.doc" gave me a listing of elements within the document itself.  From here, I knew that I wanted to look at "word/vbaProject.bin".

2.  "C:\Python27>zipdump.py -d d:\tips\file.doc word/vbaProject.bin" gave me a bunch of compressed stuff sent to the console.  Okay, so good so far.

3.  "C:\Python27>zipdump.py -d d:\tips\file.doc word/vbaProject.bin | oledump.py" gave me some output that I could use, specifically:
  1:       445 'PROJECT'
  2:        41 'PROJECTwm'
  3: M   20159 'VBA/ThisDocument'
  4:      3432 'VBA/_VBA_PROJECT'
  5:       515 'VBA/dir'

Now, I've got something I can use, based on what I'd read about here.  At this point, I know that the third item contains a "sophisticated" macro.

4.  "C:\Python27>zipdump.py -d d:\tips\file.doc word/vbaProject.bin | oledump.py -s 3 -v" dumps a bunch of stuff to the console, but it's readable.  Redirecting this output to a file (i.e., " > vba.txt") lets me view the entire macro.

Addendum 14 Jan 2015 - More Extracting the Macro
Didier posted this following image to Twitter recently, illustrating the use of oledump.py:

What It Looks Like: Malware Infection via a Weaponized Document

Okay...I lied.  This is my last blog post of 2014.

A couple of weeks ago, Ronnie posted regarding some analysis of a weaponized document to the PhishMe.com blog.  There is some interesting information in the post, but I commented on Twitter that there was very little post-mortem analysis. In response, Ronnie sent me a copy of the document.  So, I dusted off a Windows 7 VM and took a shot at infecting it by opening the document.

Analysis Platform
32-bit Windows 7 Ultimate SP1, MS Office 2010, with Sysmon installed - VM running in Virtual Box.  As with previous dynamic analysis I've performed, Sysmon provides not only place holders to look for, but also insight into what can be trapped via a process creation monitoring tool.

Process
Run Windows Updates, reboot to a clean clone of the VM, and double-click the document (sitting on the user profile desktop).  The user profile used to access the document had Admin-level privileges, but UAC had not been disabled.  After waiting a few moments after the launch of the document, the application (MS Word) was closed, and the VM shut down cleanly.

I purposely did not run a packet capture tool, as that was something that had been done already.

Analysis
Initial attempts to view the file in a hex editor caused MSE to alert on TrojanDownloader:O97M/Tarbir.  After opening the file, waiting, and shutting down the VM cleanly, I created a timeline using file system, WEVTX, Prefetch, and Registry metadata.  I also created a separate micro-timeline from the USN change journal - I didn't want to overpopulate my main timeline and make it more difficult to analyze.

Also, when I extracted the file from the archive that I received, I named it "file.docx", based on the contents (the structure was not the older-style OLE format).  When I double-clicked the file, MS Word opened but complained that there was something wrong with the file.  I renamed the file to "file.doc", and everything ran in accordance with Ronnie's blog post.

Findings
As expected, all of the files that Ronnie mentioned were created within the VM, in the user's AppData\Local\Temp folder.  Also as expect, the timeline I created was populated by artifacts of the user's access to the file.  Since the "Enable Editing" button had to be clicked in order to enable macros (and run the embedded code), the TrustRecords key was populated with a reference to the file.  Keep in mind that many of the artifacts that were created (JumpList entries, Registry values, etc.) will persist well beyond the removal/deletion of the file and other artifacts.

While I did not capture any of the off-system communication (i.e., download of the malware), Sysmon provided some pretty interesting information.  I looked up the domain in Ronnie's post, and that gave me the IP address "50.63.213[.]1".  I then searched for that IP address in my timeline, and found one entry, from Sysmon...Powershell had reached off of the system (Sysmon/3 event) to that IP address (which itself translates to "p3nlhg346c1346.shr.prod.phx3.secureserver[.]net"), on port 80.  Artifacts of Powershell's off-system communications were the HKLM/Software/Microsoft/Tracing/powershell_RASMANCS and HKLM/Software/Microsoft/Tracing/powershell_RASAPI32 keys being created.

Per Ronnie's blog post, the file "444.exe" is downloaded.  The file is deleted after being copied to "msgss.exe".  The strings within this file (msgss.exe) indicate that it is a Borland Delphi file, and contains the strings "GYRATOR" and "TANNERYWHISTLE" (refer to the icon used for the file).  The PE compile time for the file is 19 Jun 1992 22:22:17 UTC.  The VirusTotal analysis of this file (originally uploaded to VT on 12 Dec) can be found here.

Persistence Mechanism:  User's Run key; the value "OutLook Express" was added to the key, pointing to the msgss.exe file.

An interesting artifact of the infection occurred at the same time that the msgss.exe file was created on the system and the Run key value created so that the malware would persist; the key "HKCU/full" was created.  The key doesn't have any values...it's just the key.

To extend Corey's discussion of Prefetch file contents just a bit, the Prefetch file for WinWord.exe included references to RASMAN.DLL, RASAPI32.DLL, as well as other networking DLLs (W2_32.DLL, WINHTTP.DLL).

Given the off-system communications, I located and extracted the WebCachev01.dat file that contains the IE history for the user, and opened it using ESE DatabaseView.  I found no indication of the host being contacted, via either IP address or name.  Additional testing is required but it would appear that the System.Net.WebClient object used by Powershell does not leave traces in the IE history (i.e., the use of the WinInet API for off-system communications would leave traces in the history).  If that's the case, then from an infrastructure perspective, we need to find another means of detecting this sort of activity, such as through process creation monitoring, the use of web proxies, etc.

Take-Aways
1. Threat intel cannot be based on analysis in isolation.

Okay, I understand that this is just a single document and a single infection, and does not specifically represent an APT-style threat, but the point here is that you can't develop "threat intelligence" by analyzing malware in isolation.  In order to truly develop "threat intelligence", you have to look how the adversary operates within the entire infrastructure eco-system; this includes the network, memory, as well as on the host.

I'm also aware that "APT != malware", and that's absolutely correct.  The findings I've presented here are more indicators than intel, but it should be easy to see not just the value of the analysis, but also how it can be extended.  For example, this analysis might provide the basis for determining how an adversary initially gained access to an infrastructure, i.e., the initial infection vector (IIV).  Unfortunately, due to a number of variables, the IIV is often overlooked, or assumed.  When the IIV is assumed, it's often incorrect.  Determining the IIV can be used to see where modifications can be made within the infrastructure in order to improve prevent, detection, and response.

Looking specifically at the analysis of this weaponized document, Ronnie provided some insight, which I was then able to expand upon, something anyone could have done.  The focus of my analysis was  to look at how the host system was impacted by this malware; I can go back and redo the analysis (re-clone the VM), and run the test again, this time pausing the VM and capturing the memory for analysis via Volatility, and extend the understanding of the impact of this document and malware even further.  Even with just the timeline, the available indicators have been expanded beyond the domain and hash (SHA-256) that was available as of 15 Dec.  By incorporating this analysis, we've effectively moved up the Pyramid of Pain, which is something we should be striving to do.  Also, be sure to check out Aaron's Value of Indicators blog post.

2.  Host analysis significantly extends response capability.

The one big caveat from this analysis is the time delta between "infection" and "response"; due to the nature of the testing, that delta is minimized, and for most environments, is probably unrealistic.  A heavily-used system will likely not have the same wealth of data available, and most systems will very likely not have process creation monitoring (Sysmon).

However, what this analysis does demonstrate is, what is available to the responder should the incident be discovered weeks or months after the initial infection.  One of the biggest misconceptions in incident response is that host-based analysis is expensive and not worth the effort, that it's better to just burn the affected systems down and then rebuild them.  What this analysis demonstrates is that through host analysis, we can find artifacts that persist beyond the deletion/removal of various aspects of the infection.  For example, the file 444.exe was deleted, but the AppCompatCache and Sysmon data provided indications that the file had been executed on the system (the USN change journal data illustrated the creation and subsequent deletion of the file).  And that analysis doesn't have to be expensive, time consuming, or difficult...in fact, it's pretty straightforward and simple, and it provides a wealth of indicators that can be used to scope an incident, even weeks after the initial infection occurred.

3.  Process creation monitoring radically facilitates incident response.

I used Sysmon in this test, which is a pretty good analog for a more comprehensive approach, such as Sysmon + Splunk, or Carbon Black.  Monitoring process creation lets us see command line arguments, parent processes, etc.  By analyzing this sort of activity, we can develop prevention and detection mechanisms.

This also shows us how incident response can be facilitated by the availability of this information.  Ever since my early days of performing IR, I've been asked what, in a perfect world, I'd want to have available to me, and it's always come back to a record of the processes that had been run, as well as the command line options used.  Having this information available in a centralized location would obviate the need to go host-to-host in order to scope the incident, and could be initially facilitated by running searches of the database.

Resources
Lenny Zeltser's Analyzing Malicious Documents Cheat Sheet

Final Post of 2014

As 2014 draws to a close, I thought I'd finish off the year with one last blog post.  In part, I'd like to thank some folks for their contributions over the past year, and to look forward to the coming year for what they (and others) may have in the coming year.

I wanted to thank two people in particular for their contributions to the DFIR field during 2014.  Both have exemplified the best in information sharing, not just in providing technical content but also in providing content that pushes the field toward better analysis processes.

Corey's most recent blog post continues his research into process hollowing, incorporating what he's found with respect to the Poweliks malware.  If you haven't taken a good look at his blog post and incorporated this into your analysis process yet, you should strongly consider doing so very soon.

Maria's post on time stomping was, as always, very insightful.  Maria doesn't blog often but when she does, there's always some great content.  I was glad to see her extend the rudimentary testing I'd done and blogged about, particularly because very recently, I'd seen an example of what she'd blogged about during an engagement I was working on.

Maria's also been getting a lot of mileage out of her Google cookies presentation, which I saw at the OSDFCon this year.  If you haven't looked at the content of her presentation, you really should.  In the words of Hamlet, "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy", and I'm sure Maria was saying, "There are more things in a Windows image than are dreamt of in your timeline."

Tying both Corey and Maria's contributions together, I was doing some analysis recently regarding a particular malware variant that wrote it's files to one location, copied them to another, time stomped those files, and injected itself into the svchost.exe process.  This variant utilized the keystroke logging capability of the malware, and the keystroke log file was re-stomped after each successive update.  It was kind of like an early nerd Christmas gift to see what two well respected members of the community had talked about right there, in the wild.  In the words of one of my favorite characters, "Fascinating."

Volatility
The year would not be complete without a huge THANK YOU to the Volatility folks for all they do, from the framework, to the book, to the training class.  2014 saw me not only attending the course, but also receiving a copy of the book.

Shellbags
On the whole, it might be fair to refer to 2014 (maybe just the latter half) as the "Year of the Shellbag Research".  Eric Zimmerman (Shellbag Explorer), Willi Ballenthin, Dan Pullega, and Joachim Metz should be recognized for the work they've been putting into analyzing and documenting shellbags.  To learn more about what Eric and others have done to further the parsing and analysis of shellbags, be sure to check out David Cowen's Forensic Lunch podcasts (28 Nov, 12 Dec).

TriForce
Speaking of David Cowen, I still think that TriForce is a great example of the outcome of research in the field of forensic analysis.  Seriously.  I don't always use things like the USN change journal in my analysis...sometimes, quite simply, it's not applicable...but when I have incorporated into a timeline (by choice...), the data has proved to be extremely valuable and illuminating.

There are many others who have made significant contributions to the DFIR field over the past year, and I'm sure I'm not going to get to every one of them, but here are a few...

Ken Johnson has updated his file history research.
Basis Technology - Autopsy 3.1
Didier Stevens - FileScanner
Foxton Software - Free Tools
James Habben - Firefox cache and index parsers

Lateral Movement
Part of what I do puts me in the position of tracking a bad guy's lateral movement between systems, so I'm always interested in seeing what other analysts may be seeing.  I ran across a couple of posts on the RSA blog that discussed confirming Remote Desktop Connections (part 1, part 2).  I'm glad to see someone use RegRipper, but I was more than a little surprised that other artifacts associated with the use of RDP (either to or from a system) weren't mentioned, such as RemoteConnectionManager Windows Event Log records, and JumpLists (as described in this July, 2013 blog post).

One of the things that I have found...interesting...over time is the number of new sources of artifacts that get added to the Windows operating system with each new iteration.  It's pretty fascinating, really, and something that DFIR analysts should really take advantage of, particularly when we no longer have to rely on a single artifact (a login record in the Security Event Log) as an indicator, but can instead look to clusters of artifacts that serve to provide an indication of activity.  This is particularly valuable when some of the artifacts within the cluster are not available...the remaining artifacts still serve as reliable indicators.

WRA Contest
Finally, as the year draws to a close, here's an update on the WRA 2/e Contest. To date (in over 2 months) there has been only a single submission.  I had hoped that the contest would be much better received (no coding required), but alas, it was not to be the case.

10 Years of Blogging

That's right...my first blog post was ten years ago today.  Wow.

Over the passed ten years, some things have changed, and others haven't.

As the year comes to a close, don't forget about the WRF 2/e Contest.

WRF 2/e Contest

I recently posted that Syngress has agreed to publish a second edition of Windows Registry Forensics, and in that post, I mentioned that I wanted to provide those in the community with an opportunity to have input into the content of the book prior to it being published.  I know that it's only been a couple of days since the post was published, but historically, requests like these haven't really panned out.  As such, I wanted to take something of a different approach...at the recommendation of a friend, and stealing a page from the Volatility folks, I'm starting a contest for submissions of "case studies" to appear in the second edition.

Contest
So what I'm looking for is submissions of detailed case studies (or "write-ups", "war stories", etc...I don't want to get tangled up on the terminology) of your triumphs via and innovations in Registry analysis.

Please read through this entire blog post before sending in a submission.

What I don't want is case information, user and system names, etc.  Please provide enough detail in your write-up to give context, but not so much that case information is exposed and privacy is violated.

For the moment, I plan to accept submissions until midnight, 31 Dec 2014.  I may extend that in the future...it really depends on how the schedule for the book writing works out, how far I get, how many submissions come in, etc.  The really good submissions will be included in the book, and the author of the submission will received a signed copy of the book.  And yes, when I say "signed", I mean by me.  That also means that your submission needs to include a name and email address, so that I can reach back to you, if your submission is accepted, and get your mailing address.

I'm looking for the top 10 or so submissions; however, if there are more really good ones than just ten, I'll consider adding them, as well.

Consideration will be given to...
Those submissions that require the least effort to incorporate into the book, with respect to spelling and grammar.  I'm all about cut-and-paste, but I don't want to have the copy editor come back with more modifications and edits than there is original text.  I can take care of incorporating the submission into the book in the correct format, but I don't want to have to spend a great deal of time correcting spelling and grammar.

Those submissions that are more complete and thorough, illustrating the overall process.  For example, "...I looked at this value..." or "...I ran RegRipper..." isn't nearly as useful as correlating multiple Registry keys and values, even with other data sources (i.e., Windows Event Logs, etc.).

Those submissions that include more than just, "...I used RegRipper..." or "...I used auto_rip...".  Submissions should talk about how tools (any tools, not just the ones mentioned...) were used.

Those submissions that include process, data, results, RR plugins used, created, or modified, etc.

Note that if you include the newly created or modified plugin along with your submission, the plugin will be added to the RR distribution.

Submissions
Send submissions so to me as text.  Use "WRF 2/e contest submission" as the subject line.   If you have images (screen captures, etc.) that you'd like to share, reference the image in the text ("insert figure 1 here"), and provide the image in TIFF format.

If you have multiple files (the write-up, a plugin, images, etc.), just zip them up.

Please include your name along with the information.  If you do not want your name included in the content when it's added to the book, please specify as such...however, anonymous submissions will not be considered, as I may want to reach back to you and ask a clarifying question (or two).  So, please also be willing to answer questions!  ;-)

Please let me know if it would be okay to post the submission to this blog, and if so, should your name be included (or not).

If you have any questions about this contest, please feel free to ask.

RegRipper v2.8 is now on GitHub

RegRipper v2.8 is now available on GitHub.

From this point forward, this repository should be considered THE repository for RegRipper version 2.8.  If you want a copy of RegRipper, just click the "Download ZIP" button on the right of the browser window, and save the file...doing so, you'll have the latest-and-greatest set of plugins available.

If you have any questions, please feel free to contact me.

Windows Event Logs

Dan recently tweeted:

Most complete forensics-focused Event Log write-ups? #DFIR

I have no idea what that means.  I'm going to assume that what Dan's looking for is information regarding Event Logs records that have been found useful or valuable to forensic analysts, or potentially could be.

EVT vs EVTX
Windows XP is no longer supported by Microsoft, but there are still XP and 2003 systems out there, and as such, some of us are still going to need to know the difference between Event Logs (XP, 2003), and Windows Event Logs (Vista+).

Besides the binary differences in the records and Event Log files themselves, on XP/2003, there were three main Event Log files; System, Application, and Security.  On my Windows 7 system, a 'dir' of the winevt\Logs folder reports 143 files.  So, there is a LOT of information being recorded by default on a Windows 7 system; while not all of it may be useful to you, there is a great deal of information that can be extracted from the logs when used properly.

Wevtx.bat
When I released Windows Forensic Toolkit 4/e, one of the things included in the additional materials is a batch file, wevtx.bat.  What the batch file does is use LogParser to parse a directory full of .evtx files, and then parse those entries into TLN format for inclusion in a timeline.  The tool evtxparse.exe, used by the batch file, makes use of a mapping file (i.e., eventmap.txt) to map event source/ID pairs to an artifact category tag.  As such, when the entry in written to a timeline, records such as "Microsoft-Windows-Security-Auditing/4624" are prepended with an appropriate tag (i.e., "[Logon]"), based on the artifact category.

I really love this tool!  What I like about it is that it's easy to update (eventmap.txt is just a text file), I can add comments to it to show the source of the information I used to map an event record to something specific, and it acts as a fantastic little repository for all of my past experiences.  Not only is it a great repository, but it's incorporated right into the tools that I use on just about every engagement.

Records
Here are some of the event source/ID pairs that I've found to be useful during investigations, for such things as malware detection, determining the window of compromise, etc.  I'll say up front that these records are not 100% infallible, and may not have extremely high fidelity (some do, others don't...), but they've worked quite well for me at one time or another, so I'll share them here.

Microsoft-Windows-DNS-Client/1014 – DNS name resolution timeout; I've used this one more than once to help demonstrate that malware was on a system, even in the face of anti-forensics techniques (time stomping the malware files, deleting the malware files, etc.). It's not a 100%, infallible indicator, but it's worked for me more than once.  What has also helped is when this event record was seen; in a timeline, I could see that it occurred shortly after a user logged into a laptop, and before the user connected the system to a WAP.  This helped me narrow down the persistence mechanism for the malware.

Microsoft-Windows-Security-Auditing/4720 - user account created; because the bad guys do this from time to time.

McLogEvent/257 – McAfee malware detection - McAfee AV may detect malware behaviors (i.e., run from a Temp folder, etc.) without actually detecting the EXE itself.  This can be very valuable in helping you determine how malware got onto a system.  Also, the AV product may be configured to warn only, and take no action..so, correlate the event records (UTC) to the entries in the McAfee logs (local system time)

Microsoft-Windows-Windows Defender/3004 – Windows Defender malware detection

Service Control Manager/7045 – A service was installed on the system

Service Control Manager/7030 – A service is configured to interact with the desktop

Microsoft-Windows-TaskScheduler/106 - New Scheduled Task registration

Beyond individual event records (source/ID pairs), one of the aspects of the newer versions of Windows (in particular, Windows 7) is that there are a lot of events that are being recorded by default, across multiple Event Log files.  What I mean is that when some events occur, multiple event records are recorded, often across different Event Log files.  For example, when a user logs into a system at the console, there will be an event recorded in the Security Event Log, a couple in the Microsoft-Windows-TerminalServices-LocalSessionManager/Operational.evtx log, and a couple of events will also be recorded in the Microsoft-Windows-TaskScheduler/Operational.evtx log.  Alone, each of these individual events may get little attention from an analyst, but when placed together in a timeline, they leave an indelible mark indicating that a user logged into the system.

Now, what's really great about this is that some of the Event Logs "roll over" faster than others.  As such, some of the source/ID pairs that are part of an indicator cluster may have been expired from their respective Event Logs.  However, the remaining source/ID pairs in the cluster will still provide a very good indicator that that event in question took place.  This is particular useful for infrequent events, and I've used this information more than once to demonstrate repeated activity going back weeks and even months prior to what was thought to be the date of interest.

Anti-Forensics
Event auditing is one of those things that just happens in the background on Windows systems.  This is great, because sometimes Event Log records can help us determine if anti-forensics techniques have been employed.  For example, using Event Log records, you can determine if someone has changed the system time.

During an exam, I found that a system had been infected with malware that installed as a Windows service, and during the installation process, the .exe file had been time-stomped.  Fortunately, when the malicious service was installed, an event source/ID pair of "Service Control Manager/7045" was created, indicating that a new service had been installed on the system.  I was able to correlate that information with other sources (MFT, etc.) to better determine the correct time of when the malicious .exe was created on the system, and nail down the infection vector.

Carving
If you need to carve Windows Event Log records, for any reason...from unallocated space, memory, the pagefile, whatever...the tool to use is Willi Ballentin's EVTXtract. The "tool" is really a set of Python scripts that you run consecutively against the data in order to recover Windows Event Log records.  I've used these scripts a couple of times, and even had a fellow team member use them on an engagement and quite literally recover the "smoking gun".

When carving for deleted records on a Windows XP or 2003 system, I use a custom Perl script that I wrote that's based on some of the code I've released with my books.

Timelines
When all this is said and done, a blog post on just individual Windows Event Log records isn't really all that valuable.  Yes, I've created timelines from just a handful of *.evtx files, for use in triage, etc.  This has proved to be extremely valuable to me.

Resources
WindowsIR: Timeline Analysis
SANS Reading Room: Detecting Security Events Using Windows Workstation Event Logs
NSA: Spotting the Adversary with Windows Event Log Monitoring

Publishing DFIR Books

I recently received notification that Syngress is interesting in publishing a second edition of Windows Registry Forensics.  I submitted my proposed outline, the reviews of which were apparently favorable enough to warrant a second edition.

I've blogged before regarding writing DFIR books, and that effort seems to have fizzed a bit.  I wanted to take the opportunity to give another shot and see if I couldn't resurrect this topic, or a portion of it, just a bit.  So, the purpose of this blog post is two-fold: to set expectations of the upcoming edition, as well as offer those in the community who are interested to have input into the development (what goes in it) of the book.

Based on the reviews of my proposed outline, as well as some of the online reviews (Amazon, SecurityXploded, etc.), I wanted address a few of the comments I  tend to see more frequently than most, and then allow those who read this post to make their own comments.

From the SecurityXploded review:

It would have been better if author would have put up the approach or step by step procedure one should follow while analyzing live & offline system.

...and...

Putting things straight and then discussing relevant tools at each step will be more beneficial.

This is always an interesting statement to pursue, in part because I see it pretty often in things I've written (such as the HowTo blog posts from July 2013), as well as course materials and presentations I, and others, have put together.  As I'm sure others have done, I try to write something that is general enough to apply across multiple situations, and hope that the reader is able to extrapolate what I've written so it can be used in their specific situation.  My thinking...and it may be wrong...is that analysts must be able to take what they've learned from white papers, presentations, training courses, and other sources, and apply that information and knowledge to what they have available to them.  Not everything that an analyst encounters is going to fit neatly into a training course or whitepaper; there's always going to be some twist or variation, based on the goals of the examination, the data available, etc.  As such, analysts need to be able to build on core principles and basic knowledge to be able to meet the challenges before them.

For example, an analyst should be able to review the SANS checklist for analyzing USB devices on Windows 7, read this HowTo (Correlate an attached device to a user) and this HowTo (Determine user access to files), and be able to determine the files a user may have accessed from a thumb drive that had been attached to their system.  Part of this entails that there has to be some point at which a common, baseline level of knowledge must be assumed.  For example, do you assume that most folks know what the Registry is, or how to determine the CurrentControlSet from a System hive extracted from an acquired image?

This is why I advocate that analysts must share their experiences; no one of knows everything, but together, we can know more than any one of us.  None of us is going to have the same experiences as everyone else, but we can all learn from each other's experiences.

Another comment from the SecurityXploded blog post:

However if you are expecting to cover all those important registry locations then you will be disappointed and it is not feasible in one book. 

This is exactly right, and goes back to one of the core things I learned about writing DFIR books...you're not going to make everyone happy.  Someone's always going to be disappointed about what they didn't find in the book.  But you know what...that's okay.  It has to be...if someone tried to write a book that covered everything, that book would never be completed.

I've been working directly in the DFIR field for a little more than 14 years, and I will be the first to admit, I have not seen everything there is to see.  I've done DFIR in an internal, FTE position, as well as as a consultant.  For a bit more than three years, I did PCI response while at IBM ISS.  While my work has evolved over time, there is still a great deal that I haven't seen, and when I write books or blog posts, I most often base what I write about my own direct experiences.  Now and again, someone will share data with me, and I will learn a little something from their experiences.  I like to sprinkle those indirect experiences in, as well, because they broaden the reach of the material.

In WRF 2/e, I do plan to provide examples of analysis processes I've used, based on goals I've been given, as well as things that I've seen during analysis.  However, no one should expect to pick up this book (or any other DFIR book, for that matter) and find the answer to their specific issue or question.  This is particularly true if no effort is made to contact the author while the book was being written.

From the WRF 2/e outline reviews, as well as from other sources, I've seen this little gem:

You need to provide a chapter on Windows Phone 8.

Anyone remember this blog post?  There were two important take-aways from that blog post.  One was that RegRipper does work with the Windows Phone 8 Registry, and what's needed is sample data and input into what examiners find important, so that plugins can be written.  The second is that the hive files were provided to me...I do not own a Windows Phone 8, nor do I have access to these devices, through work or any other means.  Cindy Murphy did send me some hive files extracted from a Windows Phone 8, but that's one system and a very limited amount of data.  I can't write about what I don't know and didn't experience, and can't provide screen captures illustrating data that I do not have.  Would I like to write more about the Windows Phone 8, particularly the Registry?  Sure.  Without a doubt.  But without actual data, I can't really be expected to write much of anything, can I?

Okay, those are just a few of the comments/statements I've seen in reviews, and like I said, I only wanted to address those that I see regularly.  If you have any thoughts or comments about the content that should appear in WRF 2/e, I'd be glad to hear and consider them.  Thanks.

Stuff

IR
Here's a really good...no, I take that back...a great blog post by Sean Mason on "IR muscle memory".  Take the time to give it a read, it'll be worth it, for no other reason than because it's valuable advice.  Incident response cannot be something that you talk about once and never actually do; it needs to be part of muscle memory.  Can you detect an incident, and if so, how does your organization react?  Or, if you receive an external notification of a security incident, how does your organization respond?


A couple of quotes from the blog post that I found interesting were:

...say, “Containment” without having any understanding of what is involved...

Yes, sometimes a consultant (or CISSP) will say this, and sometimes, there is that lack of understanding of how this will affect the business.  This is why having IR built into the DNA of an organization is so important...understanding how the business will be affected by some response or containment procedure is critical.

There is also a modicum of patience and discipline required when it comes to containment, particularly when it comes to targeted threats.  If the necessary instrumentation is not in place to monitor the environment, then prematurely pulling the trigger on some containment procedures rather than taking the time to prepare and conduct the containment procedures in a near-simultaneous manner will likely cause the threat actors to react, changing what they do.  When dealing with these incidents, if someone on the response team decides, "...hey, I can make that change now, so I'll go ahead and take care of it..." can lead to a lot more work.

Another comment from the blog post:

...as a leader and a technologist, you always want everyone to know everything wing-to-wing, and while this can work great in a small organization the reality is that it doesn’t scale for a number of reasons in larger orgs. 

I agree wholeheartedly with this.  For larger teams in particular, it doesn't scale well for everyone to be an expert in everything, but it does work well to have designated pockets of deep expertise.

I know that I'll never be as good a malware reverse engineer as some of the folks I've had the honor of working with.  I can put a great deal of effort into becoming good at it, but that effort would be effort that I wouldn't be spending become better at DFIR analysis.  Also, I've found that an effective approach is to gather as much as I can about the malware...OS and version it's installed on, where it was found in the file system, persistence mechanism, any artifacts or indicators associated with the malware, etc.  I provide these to the RE analyst, and continue my analysis while they dig deep into the malware itself.  When the RE analyst finds something, they provide it back to me and I continue with my analysis.

A great example of this occurred a number of years ago.  I have found some malware that was used to steal banking credentials (NOT Zeus) and shared it with the RE analyst, providing a second file and the information/intel needed to run the malware.  The malware itself was obfuscated, and in return I got a mutex (I didn't have a memory dump, but I did have a hibernation file and the pagefile), the API used for off-system communications, and other valuable information.  With that, I was able to nail down the specific user affected, the initial infection vector, when the infection occurred, etc.

On smaller teams, you won't be able to have those silos, but on larger teams, in larger organizations, it helps to pockets of deep expertise, and someone you can reach to for further assistance.  This is particularly valuable in incidents, due to the ability to perform parallel analysis; rather than having one analyst who many not, say, analyze disk images on a regular basis try to wring as much information and intel out of an acquired image as they can while working an IR engagement, have that task run in parallel by someone with a deeper expertise.  You're likely to get the info you need (and more) in a much more timely manner, while not loosing any time or focus on the engagement itself.  On smaller teams, you're likely going to have a broader base of skill sets that aren't as deep as what you will find with individuals on larger teams.  Larger teams can take advantage of pockets of skill sets, and even geographic dispersion, to keep the flow of the incident response going.

The rest of Sean's blog post is equally interesting.  Sean goes on to provide his thoughts on people, process, and metrics, all with great insight.

To further Sean's thoughts, a great follow-on to his post is this article from WSJ; in particular, the following quote from that article:

“You are going to get hacked. The bad guy will get you. Whether you are viewed as a success by your board of directors is going to depend on your response.”

IR Fail?
Here's an interesting article from Kelly Jackson Higgins (DarkReading) that talks about Fortune 500 companies having IR teams, but many being pessimistic about their team's ability to handle a data breach.  From my perspective, it's good to see that more firms are moving to having a computer security incident response plan, or CSIRP, and that these companies are actually thinking about things like, "...we need a plan...", and "...how good is our IR team?"  Even if there is pessimism about the current team's effectiveness, at least there's thought going in that direction, and a realization and admission of the team's current state.  From my perspective, this isn't really so much of a failure as it is a success that we've come this far.

From the article:

So why are aren't Target, TJ Maxx, and others sharing their war stories to help the next potential victim?

Yeah, you're not going to.  Sharing is not a natural reaction within the DFIR community.  This doesn't mean that it doesn't happen...years ago, while working an IR with a client, I heard that there was a forum in the local area where IT folks from different organizations in the same vertical came together and discussed issues and solutions.  In fact, the DLP solution that my client had in place, which proved to be extremely valuable during the IR engagement, had been purchased as a result of engaging with others in their community.  My point is, sharing can be powerful, and sharing information or intel that helps the next guy when they're attacked doesn't necessarily give away 'secret sauce' or competitive advantage.

Having an IR plan in place isn't enough, either.

No, it's not.  You can't have a plan written by consultants sitting on a shelf...that's worse than not having a plan at all, because the organization will see that binder sitting on the shelf (literally or figuratively) and think that they've checked a box and have achieved some modicum of success.  A CSIRP needs to be organic to an organization (remember Sean's blog post?); it needs to be owned and practiced by the organization.  You can get assistance in writing it, reviewing it, and practicing the processes laid out in the CSIRP.  Having an outside consulting firm come in and run an IR exercise...anything from a table top (in the military, we called this a "tactical exercise without troops", or TEWT) exercise to a full-on IR engagement...is a fantastic idea.

Over the years, I've seen a wide variety of organizations as a consultant.  I've seen those that have been caught completely by surprise by a data breach, those that have IR plans but do not employ them, and I've seen those that have a practiced plan and want someone there to help guide them.  Invariably, those organizations that have been thinking seriously about the need for incident detection and response end up faring much better than others, in a variety of metrics, including the overall cost of the incident.

RegRipper
In a few short weeks, I will be presenting at OSDFCon, talking about some changes to RegRipper that I've had in the works.  I'll say right now that the changes I've been thinking about and working on are not ones that will significantly impact the use of the tool...so come on by and give it a listen.

OSDFCon and OMFW
I've attended and presented at OSDFCon before, and this is has always been a really great conference to attend.

Whether you're going to be at OSDFCon or not, I highly recommend that you consider attending the Open Memory Forensics Workshop, or OMFW 2014.  This is the premier conference on memory analysis, put on by the top minds in memory analysis, from the Volatility Foundation.

If you're attending OSDFCon, be sure to come see Mari DeGrazia's presentation!

RegRipper Tutorial
Speaking of RegRipper, this tutorial was posted recently regarding how to set up and use RegRipper...I have say, I have somewhat mixed feelings about it.  Part of me appreciates the interest in the tool, but

In the name of full disclosure, the author did contact me and ask me to review the article after it was complete.  I responded, but to be honest, at the time that the request came in, I didn't have the cycles to focus on reviewing the article, and I definitely didn't have the cycles to address everything that I read in the article.  So what you're seeing now is what I've worked on a few minutes at a time, here and there, since the article was published.  I'm not going to address everything in the article, because I simply don't have the time to do so, so what I opted to do was pull out just a couple of comments and address them here.

For example...

I have often heard RegRipper mentioned on forums and websites and how it was supposed to make examining event logs, registry files and other similar files a breeze. 

I'm not sure which forums or websites state this, but this is not the case at all.  RegRipper is named as it is because it's intended for use against the Windows Registry...and only the Registry.  It's not intended for use against any other files, in particular the Windows Event Logs.  Right after I first released RegRipper, I did receive a request to have it parse PST files, but that simply wasn't/isn't practical.

As I wrote earlier there is a huge community out there writing plugins for RegRipper.

First off, there is no mention of "a huge community" in the tutorial, up to that point.  Second, there is not a "huge community out there writing plugins".  Yes, some plugins have been submitted over time, and some folks have suggested modifications to plugins...but there is not a "huge community" by any means.  In fact, my understanding is that the vast majority of users simply download the tool and run the GUI...and that's it.  Asking users specifically, via email or in person, what they'd like to see done to make the tool more useful does not often lead to responses such as requests for new plugins.

I could continue with a lot of the different things I found to be amiss (such as in the Downloads section), but it is not my intent to deride this effort.  Again, I greatly appreciate the interest in the tool, and I wanted to address a couple of the comments because I felt that they were wide-spread misconceptions that should be addressed.  I'm not going to do a walk-through and correct everything I find...instead, I'll refer folks to the various blog posts I've written, as well as to Windows Registry Forensics.

Windows Phone 8 and RegRipper

Last week, Cindy Murphy (@cindymurph) sent me some Registry hive files...from a Windows Phone 8.  This was pretty fascinating, and fortunate, because I'd never seen a Windows phone, and had no idea if it had a Registry.  Well, thanks to Cindy, I now know that it does!

Looking at the hive files was pretty fascinating.  The first thing I did was open one of the smaller hive files in UltraEdit, and I could clearly see that it followed the basic structure of a Registry hive file (see chapter 2 of Windows Registry Forensics).  Next, I opened one of the hives in a viewer, and saw that the hive file opened nicely; however, there were clearly differences in what I expected to see, with respect to a desktop or laptop running Windows.

Finally, I ran a couple of RegRipper plugins against the System hive that Cindy provided, in part because I saw that there were some keys with the same paths as the ones I generally see on Windows systems.  For example, the compname.pl and timezone.pl plugins worked just fine.  For the Software hive, the profilelist.pl plugin worked just fine, although there was only one profile listed.  Interestingly enough, the SAM hive had the correct structure and a root key, but no subkeys.

So, if there's a question as to whether or not RegRipper works when run against hive files from a Windows Phone 8, the answer is "yes", but with a caveat...you can't expect all of the plugins to work, simply because the current RegRipper plugins are intended to run against hives extracted from Windows computer systems.  I would like to be able to write plugins for the phone hives, but I won't be able to that until more data becomes available and more analysts can identify what it is they find important and of-interest in these hive files.

I'd like to send a thank you to Cindy for sharing the hive files and helping to expand my view into this data source a bit.

What Does That Look Like, Pt II

In my last post, I talked about sharing what things "look like" on a system, and as something of a follow up to that post, this article was published on the Dell SecureWorks blog, illustrating indicators of the use of lateral movement via the 'at.exe' command.  I wanted to take a moment to provide some additional insight into that post, with a view towards potentially-available indicators that did not make it into the article, simply because I felt that they didn't fit with the focus of the article.

Terminology
Some definitions before moving on...I'm providing these as living, "working" definitions that can be tweaked and modified as we go along.  I know that going into this, there will be those who ask for definitions, as well as those who see the definitions and simply say, "no, that's not what that means"...and that's okay.  We have to start somewhere, right?

Artifact - an element of a data source.  A data source might be a Windows Event Log file, and an artifact would be a Windows Event Log record.

Indicator - an artifact, with some sort of context applied to it.  That context may vary, which means the value of the indicator may vary.  As I mentioned before, sharing indicators, even those we've seen before or those we believe others have already seen is very valuable, in that it allows us to increase the reliability of those indicators.

Some mathy stuff to help provide a description...

Indicator = artifact + context

TTPs - clusters of indicators that can be used to illustrate intruder or user actions

Like I said, these are working definitions that can be tweaked and modified, if necessary.  I do think that they are important to have, as it provides us with a common platform from which to launch discussion and discourse.  Too often, discussions get tangled and confused over terminology and definitions, such as the difference between a Registry key and value; the distinction may be subtle, even irrelevant to some, but to others, they speak to the clarity and precision of the discussion.

If you read through the SecureWorks article, you might think that there are some things missing, particularly from the perspective of the source system in the lateral movement.  The article states that the observed indicator of the lateral movement is an application prefetch file for at.exe, and that's pretty much the case.  The purpose of the article is to show those indicators that (a) are not often looked at, and (b) persist well beyond the removal of tools, etc.

It's clear that for this lateral movement to function properly, the file (or files) launched by the Scheduled Task need to be moved to the destination system before the task is registered.  For example, an executable file might be copied to the destination system using a command such as:

cmd.exe - copy rar.exe \\host\c$\windows\tool1.exe

The above command (which I've obfuscated, for obvious reasons) was found on a source system, in the pagefile.  Again, this was found on a source system involved in lateral movement.  This is just an example of what you might find.  Unlike the use of PSExec, the tool/executable being run needs to be available on the destination system before it can be launched via a Scheduled Task, and the use of the copy command, used in conjunction with compromised credentials, is one way to get the file on the destination system.

Now, let's assume that the tool used ("tool1.exe") is, in fact, a copy of rar.exe and is used to archive some files...you might find an at.exe command similar to the below in the pagefile, as well:

cmd.exe - at \\host 3:00am cmd /c
"c:\windows\tool1.exe a c:\windows\m.exe -m5  c:\windows\r.txt"

Again, this is just an example of what you might find...any actual commands used by the intruder would clearly vary based on what they wanted to achieve.

Something to consider with respect to the above command is the time parameter.  In the article, I provided some indicators to look for with respect to the Scheduled Task being registered, and with the use of the time parameter, you may see a time gap between when the task is registered, and when it's actually executed.  I saw one task that was run a full 30 minutes after it had been registered on the destination system.  This can have an effect on your timeline analysis, so be aware/wary of it.

When it's all said and done, the intruder may then delete files used or created using commands similar to the below:

del \\host\c$\windows\r.txt

What's interesting is that, of the above commands (run on the source system during lateral movement), only the one used to create the Scheduled Task (via at.exe) will result in an application prefetch file being created, as indicated in "Source Host" section of the article (NOTE: this will only occur on a system that is configured to create application prefetch files; by default, Windows server systems do NOT create application prefetch files).  Unless you have some instrumentation in place for monitoring process creation and command lines (Sysmon, Carbon Black, etc.), or if you're able to detect this activity and collect a memory sample from a system relatively quickly, you may miss the above indicators extracted from the pagefile.  Keep in mind, too, that the above commands are simply examples, and were found in the pagefile; as such, they have no time stamps associated with them, and cannot be tied directly to what was seen in the article.

Also, one of the things I've talked about at great length is how much what we see on a Windows system is controlled by values in the Registry; the above indicators would have been obviated if the system was configured such that the pagefile was cleared on shutdown, and the system was cleanly shut down prior to an image being acquired.

Finally, once again, the purpose of the article posted to the Dell SecureWorks blog was to illustrate those indicators that tend to persist over time.

What does that "look like"?

We've heard this question a lot, haven't we?

I attended a conference about 2 1/2 years ago, and the agenda for that conference had about half a dozen or more presentations that contained "APT" in their title.  I attended several of them, and I have to say...I walked out of some of them.  However, hearing comments from other attendees, many folks felt exactly the same way; not only were they under-whelmed, but I heard several attendees express their disappointment with respect to the content of these presentations.  During one presentation, the speaker stated that the bad guys, "...move laterally."  One of the attendees asked, "what does that look like on systems?", and the speaker's response was to repeat his previous statement.  It was immediately clear that he had no idea...but then, neither did anyone else.

Corey has asked this question in his blog, and he's also done some great work demonstrating what various activities "look like" on systems, such as when systems are exploited using a particular vulnerability.

What I'm referring to in this post isn't (well, mostly...) something like "...look at this Registry key."  Rather, it's about clusters or groups of artifacts that are indicative of an action or event that occurred on a system.

Clustering
As we share and use artifacts, we can take a step back and look at where those artifacts exist on systems.  Then we begin to see that, depending upon the types of cases we're working, artifacts are clustered in relatively few data sources.  What this means is that on drives that are 500GB, 1TB, or larger, I'm really only interested in a few MB of actual data.  This means that during incident response activities, I can focus my attention on those data sources, and more quickly triage systems.  Rather than backing up a van full of hard drives and imaging 300 or more systems, I can quickly narrow down my approach to the few systems that truly need to be acquired and analyzed.

This also means a significant speed-up for digital analysis, as well.  I don't maintain tables of how long it takes to acquire different hard drives, but not long ago, I had one hard drive that took 9 hrs to acquire, and another that was 250GB that took 5 hrs to acquire.  Knowing the data sources that would provide the biggest bang for the buck, I could have retrieved those after I connected the hard drive to the write-blocker, but before I acquired the hard drive image.

Reliability
As we share and use artifacts, we begin to see things again and again.  This is a very good thing, because it shows us that the artifacts are reliable.

Like others, including Corey, I don't see sharing artifacts on any sort of scale.  Yes, there are sites such as forensicartifacts.com, but they don't appear to be heavily trafficked or used.  Also, I generally don't find the types of artifacts I'm looking for at those sites.  I've been achieving reliability, on my own, for various artifacts by using them across cases.  For example, I found one particular artifact that nailed down a particular variant of a lateral movement technique; once I completed my analysis of that system, I went back and searched the entire timeline I'd developed for that system, and found that that artifact was unique to the event I was interested in.  I've since been able to use that artifact to quickly search successive timelines, significantly speeding up my analysis process.  Not finding that artifact is equally important, as well, because (a) it tells me that I need to look for something else, and (b) in searching for it, I can show a client that I've done an extremely thorough job of analysis, and done it much quicker.

Oxidation
A great reason for sharing artifacts is the oxidation of those artifacts.  Okay, so what does this mean?

The type of artifacts I'm referring to are, for the most part, not single artifacts.  Rather, when I talk about what something "looks like" on a system, I'm generally referring to a number of artifacts (Windows Event Log records, Registry keys/values, etc.) clustered "near" each other in a timeline.  How "near" they are...ranging from within the same second to perhaps a couple of seconds apart...can vary.  So, let's say that you're doing some testing and replicating a particular activity, and you immediately "freeze" your test system and find six artifacts that, when clustered near each other, are indicative of the action you took.

How many times as incident responders and digital forensic analysts do we get access to a system immediately after the initial intrusion occurred?  What's more likely to happen is that the initial response occurs hours, days, or even weeks after in the initial incident, and is the result of an alert or a victim notification.  Given the passage of time, these artifact clusters tend to oxidize due to the passage of time, as the system continues to run, and to be used.  For example, if a system becomes infected by a browser drive-by and IE is used in the infrastructure, some artifacts of the drive-by may be oxidized simply due to the normal IE cache maintenance mechanism.  Logs with fixed file sizes roll over, the operating system may delete files based on some sort of timing mechanism, etc.  All of this assumes, of course, that someone hasn't done something to purposely remove those artifacts.

Someone may share a cluster of six artifacts that indicate a particular event.  As others incorporate those artifacts into their analysis, the reliability of that cluster grows.  Then someone analyzes a system on which two of those six artifacts have oxidized, and shares their findings, we can see how reliable the remaining four artifacts can be.

I specifically chose to use the term "oxidize", because the term "expire" or "expired" seem to imply that the lifetime of the artifact had passed.  Sometimes, specific artifacts may not be part of a cluster, due to specific actions taken by the intruder.  For example, we've all seen files be deleted, time stomped, and other actions taken that force artifacts to be removed, rather than allowing them to timeout.

Format
At the moment, there are many questions with respect to sharing artifacts; one is the format.  What format is most useful to get examiners to incorporate those artifacts into their analysis?  Because, after all...what's the point of sharing these artifacts if others aren't going to incorporate them into their analysis processes?

During July, 2013, I posted a number of articles to this blog that I referred to as "HowTos"...they were narratives that described what to look for on systems, given various analysis goals.  Unfortunately, the response (in general) to those articles was the Internet equivalent of "cool story, bro."

A great indicator that I've used comes from pg 553 of The Art of Memory Forensics.  The indicator I'm referring to is pretty easy to pick out on that page...I've highlighted it in green in my book.  The authors shared it with us, and I found it valuable enough to write a RegRipper plugin so that I can incorporate that information directly into my own timelines for analysis...and yes, I have found this artifact extremely accurate and reliable, and as such, very valuable.  Having incorporated this indicator into my work, I began to see other artifacts clustered "around" the indicator in my timelines.  I also found that the indicator maintained it's reliability when some of those other artifacts were oxidized due to the passage of time; in one instance, the *.pf file was deleted due to how Windows XP manages the contents of that folder.

Final Thoughts
A good deal of the indicators that I'm referring to can be abstracted to more general cases.  What I mean is, an artifact cluster that is indicative of targeted threat (or "APT") can be abstracted and used to determine if a system was infected with commodity malware.  Other artifact clusters can similarly be extrapolated to more general cases...it's really more about how reliable the artifacts in the cluster are, than anything else.