Daily Blog #579: The meaning of Syscache.hve

Hello Reader,
     One of the things I've often repeated the last couple of test kitchens in regards to the Syscache hive is why does it exist. In earlier googling I thought based on its locations in slide presentations that it might be involved in the volume shadow copy system, something Maxim Suhanov does not agree with. This left the question though, what does it relate to?

Well reader long time BFF (Best Forensic Friend) Dr. Vico Marziale at blackbag may have found a pretty huge clue. In his googling, which I must say found things I did not even when searching keywords that existed in the document, found a pdf from Legato/EMC networker release notes form July of 2010.

Within these release notes the backup software states:
"The files syscache.hve, syscache.hve.LOG1, and syscache.hve.LOG2 are skipped during backup 

The files syscache.hve, syscache.hve.LOG1, and syscache.hve.LOG2, located in the %systemdrive%\system volume information folder, will be skipped during backup. These hive files are used for maintaining extended data for executable files on the system, such as SRP (Software Restriction Policies) and AppLocker. Microsoft recommends not restoring these files. These files are created from derived data and will be rebuilt over time"

Source: https://nsrd.info/blog/wp-content/uploads/2010/07/NW753_Release.pdf

So the reason this registry hive was placed in the System Volume Information folder could be that the contents of this special folder are not included in shadow copies. Also Windows Applocker was introduced in Windows 7 (https://en.wikipedia.org/wiki/AppLocker) which coincides with creation of the Syscache hive and was available in Windows Server 2008 R2:(https://blogs.technet.microsoft.com/askperf/2009/10/19/windows-7-windows-server-2008-r2-applocker/)

The included scope of Applocker includes Exes, DLL's and Scripts:

"AppLocker currently supports the following file extensions:

• Executables (.exe, .com)
• Dlls (.ocx, .dll)
• Scripts (.vbs, .js, .ps1, .cmd, .bat)
• Windows Installers (.msi, .mst, .msp)
• Packaged app installers (.appx)"

Source: https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-application-control/applocker/use-applocker-and-software-restriction-policies-in-the-same-domain

Note that the above link is for Windows 10, in Windows 7 we have not yet seen powershell scripts get logged. 

So this does appear to be the closest thing we've found to a explanation of why Syscache contains the data that it does. Now we need to find out what happened to the hive in later versions of Windows and what else we can infer from its association. 

Tomorrow I plan to return to the test kitchen, just having to much fun over the holidays to do one in time tonight. 

Also Read: Daily Blog #578

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Daily Blog #573: Forensic Lunch Test Kitchen 12/20/18 Syscache and Server 2008 R2

Hello Reader,
       Tonight after finding out from you that the Syscache.hve exists on Server 2008 R2 we switched OS's in our testing and focused on Syscahe on Server 2008 R2 and away from Windows 7 for now. Here is what we learned:

• The Syscache hive exists on an unpatched Server 2008 R2 SP1 system
• The syscache hive exists even without Amcache coming into existence
• The syscache hive on server 2008 r2 is catching executables just like Windows 7
• The syscache hive on server 2008 r2 is committing changes to the registry hive within seconds of the execution
• The syscache hive on server 2008 r2 includes executions from the Desktop, unlike Windows 7
• The syscache hive on server 2008 r2 does not appear to be catching bat files like Windows 7 but does catch and executables the bat file calls

More testing to be done! Tune in tomorrow for the Forensic Lunch and next week for more testing!

You can watch the video here:

Also Read: Daily Blog #572 

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Daily Blog #571: Forensic Lunch Test Kitchen 12/18/18 Syscache

Hello Reader,
        Another evening, another test kitchen! Tonight we looked even deeper into the Syscache and we learned:

• Bat files are recorded in the Syscache hives when executed
• Bat files and other executables run from the Desktop are not recorded in the Syscache
• Powershell files (ps1) are not caught in the Syscache hive
• Deleting a file did not eliminate it from the Syscache hive 
• Installing a program recorded its installer, but the program did not prepopulate an entry in the Syscache hive
• Creating a bat file did not pre-populate it in the Syscache hive

You can watch the video here:

Also Read: Daily Blog #570 

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Daily Blog #558: Forensic Lunch Test Kitchen 12/5/18 - Testing Syscache.hve of Amcache and Recentcache.bcf Files

Hello Reader,
     Tonight we were testing the Syscache.hve that Maxim Suhanov found in his testing of the Amcache and Recentcache.bcf files, you can read his write up here: https://dfir.ru/2018/12/02/the-cit-database-and-the-syscache-hive/

From our testing tonight here is what we learned:

• The syscache hive has three indexes
• The ObjectID key (no relation to $objid) which is inserted into the hive sequentially as new executables are run (we haven't tested executables being prechecked before running)
• The FileID key which is indexed off of the sequence and entry number of the file being executed
• The Objectlru which appears to connect the two
• The ObjectID keys contain the SHA1 hash of the contents of the executable being checked
• The ObjectID keys contain the MFT reference number of the executable being checked
• The ObjectID key does not contain the name of the executable, but you can find it by looking up the MFT reference number
• The Syscache hive appears to be updated quite quickly and is not using the transaction logs to do so 
• The syscache hive is a Windows 7 feature (haven't tested windows vista) and does not exist in the same location at least in Windows 10
• The key write time appears to be the time of first check for the current hash, we will change the hash of a known executable to test this behavior tomorrow night

You can watch the video here:

Also Read: Changes in the NtfsDisableLastAccessUpdate key

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Daily Blog #570: Forensic Lunch Test Kitchen 12/17/18 Syscache.hve

Hello Reader,
       Tonight in the Test Kitchen we expanded our testing of the Syscache hive by adding more data from our python script that is matching MFT entries to the Syscache entries. Here is what we learned:

• The syscache hive seems to record atleast exe, dll, bat and cmd files executed
• The syscache hive like the Amcache hive will store which program by sha1 hash the executable is associated with
• If there is no associated executable (no MSI installer) it will use the sha1 hash 'da39a3ee5e6b4b0d3255bfef95601890afd80709' which is the empty hash. Meaning like the Amcache it is storing information about executables not associated with any MSI installed program
• It appears, this needs more testing, that it may record more related executables than the Amcache does when a program is installed/executed

Still much more testing to be done to really make sure we understand what we are really seeing. To  be tested:

1. Installing a program but not executing it, will it appear
2. Adding full path support to the python script to understand where the associated files are being pulled from
3. Checking to see if powershell scripts get logged
4. Looking to see if deletions of programs/executables change the hive
5. Testing again to see if programs run from the desktop are include

You can watch the video here:

Also Read: Daily Blog #569 

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Daily Blog #588: Solution Saturday 1/5/19 - Syscache.hve Challenge Winner Announcement

Hello Reader,
       Sometimes you have a winning entry that exceeds all of your expectations. This week is that week for me. Maxhim Suhanov has come through with some pretty thorough testing to show what processes write to the Syscache hive and what dll's reference it. This is great work and I look forward to trying out the application registry monitoring method he found.

The Challenge:

What processes update the Syscache.hve file on Windows Server 2008 R2?

The Winning Answer:

Maxim Suhanov

https://dfir.ru/2019/01/04/what-writes-to-the-syscache-hive/

Also Read: Daily Blog #587

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Daily Blog #592: Syscache and SHA 16bit hashes

Hello Reader,
          Tonight I'm applying my Syscache research in some casework and while testing things out I realized something that I don't think was properly documented before. The Syscache SHA-1 hashes appear to be base16 hashes not base32 hashes. So before you begin looking for that malicious executable make sure you've generated the correct hash!

Also Read: The meaning of Syscache.hve

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Daily Blog #598: Forensic Lunch Test Kitchen 1/15/19 Syscache Mimikatz Server 2008 R2

Hello Reader,
       Tonight we returned to the test kitchen to try to solve the mystery of the Multiple mimikatz executables now showing up in the Syscache

Tonight we learned:

• Syscache does not appear to duplicate entries by hash
• We got some entries to appear without a hash
• We are giving the VM enough time to run its background processes to get the Syscache full written to with a new test tomorrow night
• The last write time does not appear to be updated when the program is executed again
• 64bit and 32bit executables are being recorded

You can watch the video here:

Also Read: Daily Blog #597 

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Daily Blog #572: Forensic Lunch Test Kitchen 12/19/18 Syscache and Python

Hello Reader,
      Tonight we wrote some python code to recover the full path of the files referenced in the Syscache hive, added in the ProgramID and then viewed the data in Timeline Explorer to see the relation between the executables. We learned:

• That pytsk does not have an attribute for parent reference number, so we had to extract it from the file name attribute
• That analyzemft has a great set of example code to pull your unpack's from if you are looking to write your own attribute parser
• That when I grouped my syscache entries by programID I only had 60+ entries which seems more like just what has been executed on this lightly used VM
• That there is no entry of any program run directly from my Desktop

You can get the code here: https://github.com/dlcowen/TestKitchen/blob/master/PrintFileNamesByEntry.py

You can watch the video here:

Also Read: Daily Blog #571 

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Daily Blog #594: Forensic Lunch Test Kitchen 1/11/19 Server 2008 R2 Syscache Mimikatz

Hello Reader,
  Tonight on request from a viewer we are looking to see what Mimikatz leaves behind in the Syscache hive on Windows Server 2008 R2.

Here is what we learned:

• The Syscache hive did not appear to log the 64 bit mimikatz executable from the first execution
• It did log the 32 bit mimikatz executable on first execution
• It did log the 64 bit mimikatz executable on the desktop
• It did not appear to log the 64 bit mimikatz executable in the documents directory
• The sha-1 16 bit hashes were correctly searched by Virustotal identifying mimikatz

We are going to leave the VM running over the weekend to see if the other 64 bit executables show up, see you next week. In the mean time tomorrow come back to see this weeks Sunday Funday winner with the new contest posted this Sunday.

You can watch the video here:

  

Also Read: Syscache and SHA 16bit hashes

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Daily Blog #586: Forensic Lunch Test Kitchen Server 2019 Shimcache Srum Syscache

Hello Reader,
      Tonight we extended our search to see if the Syscache hive came back to life by looking into Windows Server 2019, Here is what we learned:

• No Syscache hive by default in Server 2019
• There is a SRUM database by default in Server 2019
• There is an Amcache hive by default in Server 2019
• There is still no Preftech in Server 2019
• Shimcache showed an interesting behavior that we need to regression test back versions of Windows where executables viewed in the Explorer GUI only got entered into the Shimcache hive when they were viewable and/or highlighted in the GUI Window
• Executables not yet viewed in the GUI window scroll were not present in the Shimcache

You can watch the video here:

Also Read: Daily Blog #585

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Daily Blog #563: Forensic Lunch Test Kitchen 12/10/18

Hello Reader,
         Another test kitchen down! This time we went back to the Syscache.hve in Windows 7 trying to understand its limitations and its purpose in the operating system. Here is what we found:

• Programs executed from the Desktop whether from the command line or GUI were not being inserted into the Syscache.hve
• Programs executed from a temp directory made on the Desktop were being recorded in the Syscache.hve
• There are some sysinternals programs that are not being captured at all, these may not need any shiming

You can watch the video here:

Also Read: Daily Blog #562 

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Daily Blog #576: Sunday Funday 12/23/18 - Syscache Challenge On Server 2008 R2

Hello Reader,
    Let's finish the year right. The last challenge of 2018 needs to be special.

The Prize:

$100 Amazon Giftcard

The Rules:

1. You must post your answer before Friday 12/28/18 7PM CST (GMT -5)
2. The most complete answer wins
3. You are allowed to edit your answer after posting
4. If two answers are too similar for one to win, the one with the earlier posting time wins
5. Be specific and be thoughtful
6. Anonymous entries are allowed, please email them to dcowen@g-cpartners.com. Please state in your email if you would like to be anonymous or not if you win.
7. In order for an anonymous winner to receive a prize they must give their name to me, but i will not release it in a blog post

The Challenge:

On server 2008 r2 how would the following be seen in the syscache and what was logged:

1. Powershell empire agent

2. Meterpeter

3. Mimikatz

Also Read: Daily Blog #575

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Daily Blog #583: Sunday Funday 12/30/18 - Syscache.hve File Challenge

Hello Reader,
      This will be the first Sunday Funday for 2019 since when the submissions are received and judged the winner will be announced in 2019. Let's see what your system monitoring/debugging skills are like.

The Prize:

$100 Amazon Giftcard

The Rules:

1. You must post your answer before Friday 1/4/19 7PM CST (GMT -5)
2. The most complete answer wins
3. You are allowed to edit your answer after posting
4. If two answers are too similar for one to win, the one with the earlier posting time wins
5. Be specific and be thoughtful
6. Anonymous entries are allowed, please email them to dcowen@g-cpartners.com. Please state in your email if you would like to be anonymous or not if you win.
7. In order for an anonymous winner to receive a prize they must give their name to me, but i will not release it in a blog post

The Challenge:

What processes update the Syscache.hve file on Windows Server 2008 R2?

Also Read: Daily Blog #582

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Daily Blog #581: Forensic Lunch Test Kitchen 12/28/18 Syscache Applocker and Server 2012

Hello Reader,
         Tonight we booted up a server 2012 VM which is in line with Windows 8.1 looking to see if we could find a syscache hive with and without applocker configured. So far no such luck but we will keep trying.

If you want to watch the video you can do so here:

Also Read: Applocker and Windows 10

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Daily Blog #566: Forensic Lunch Test Kitchen 12/13/18

Hello Reader,
         This was another test kitchen were we mainly got some python code to work and in the end were able to print all of the file name's out of the file name attributes for every file referenced in the Syscache hive Object key. This isn't done though as next week I need to add in the sequence numbers to the checks to make sure I'm looking at the right file.

So next week we will be able to start making some observations about what exactly Syscache is actually tracking.

You can watch me use Eric Zimmerman's new Syscache plugin and write python code to parse the filename attribute here:

Also Read: Seeing Double (Access Dates)

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Daily Blog #599: Forensic Lunch Test Kitchen 1/16/19 Syscache Server 2008 R2 Mimikatz

Hello Reader,
   Tonight we just had a short testing session (8 minutes of actual testing) were we checked in on last nights test. Here is what we learned:

• The time delay did not effect our results
• A shutdown/power on did not add a new entries
• The registry explorer and hasher entries still had no hash
• We still saw no entries for the other mimikatz executables

On the next broadcast we will be testing the same behavior in Windows 7 and parsing the whole MFT and Syscache rather than individual records to make sure we aren't missing anything.

You can watch the video here:

Also Read: Daily Blog #598

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Daily Blog #582: Solution Saturday 12/29/18 - Syscache Server 2008 R2 Challenge

Hello Reader,
         Well no winner this week, I may have pushed a bit far in a holiday week. Tomorrow is the first contest for the new year and we will all have a fresh start.

The Challenge:

On server 2008 r2 how would the following be seen in the syscache and what was logged:

1. Powershell empire agent

2. Meterpeter

3. Mimikatz

The winning answer:

None! I'll make sure to cover this in the test kitchen

Also Read: Daily Blog #581

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Daily Blog #580: Applocker and Windows 10

Hello Reader,
          Didn't get started until very late tonight so I didn't do a broadcast, tomorrow though we will for sure. Instead I decided to see if I could get Applocker going on Windows 10 Enterprise since I already have a VM running it. I turned Applocker into audit only mode, made default rules and executed programs and ...

Nothing

So far I haven't had any entries in the event logs or a syscache hive generated, so tomorrow on the stream we will attempt to make this work again and also try this on Sever 2012, 2016 and 2019.

Also Read:  The meaning of Syscache.hve

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Daily Blog #603: Sunday Funday 1/20/19 - Server 2008 R2 System Challenge

Hello Reader,
            Last week's challenge brought out some great research and new tools. I hope that this streak of great responses continues through 2019! Let's switch focus back to the Syscache hive for this weeks challenge.


The Prize:
$100 Amazon Giftcard

The Rules:

1. You must post your answer before Friday 1/25/19 7PM CST (GMT -5)
2. The most complete answer wins
3. You are allowed to edit your answer after posting
4. If two answers are too similar for one to win, the one with the earlier posting time wins
5. Be specific and be thoughtful
6. Anonymous entries are allowed, please email them to dcowen@g-cpartners.com. Please state in your email if you would like to be anonymous or not if you win.
7. In order for an anonymous winner to receive a prize they must give their name to me, but i will not release it in a blog post

The Challenge:

On a Server 2008 R2 system make 4 copies of mimikatz (your choice of versions) 64 bit and 32 bit versions. Run them from 4 locations (of your choice) and determine what criteria determines when and if the executable gets logged in the Syscache hive and what dates are associated with the registry keys. 

Also Read: Daily Blog #602

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