A Malware Convergence at jIIr

Tuesday, December 25, 2012 Posted by Corey Harrell 5 comments
I normally wait until my blog’s anniversary to post about the direction I want to take in the upcoming year. However, there has been a perfect storm brewing over at jIIr and the eye of the storm would have passed if I waited until my anniversary. As the New Year approaches I’m looking ahead to see the direction this blog will take. jIIr has always been a platform for me to share my thoughts and research, and this will not change. In the upcoming year I foresee some changes to the content I post due to the perfect storm that is occurring. The storm I keep referring to is the convergence of different areas in my life revolving around malware. In the upcoming year I’ll be involved in: authoring a Malware Forensic book, developing a Malware Analysis course, and taking on additional malware responsibilities with my employer.

People and organizations from all walks of life are combating malware on a daily basis. The majority of the security defensive controls are ineffective at stopping the malware since attackers are bypassing them with ease. Throwing additional security controls at the issue is not the answer. What needs to be improved is the response to the malware issue; where the systems impacted are actually examined. Examining systems is one way to obtain intelligence that could be used to improve security. The question then becomes what resources are available to those wanting to take the step to start examining malware infected systems. Do those resources outline not only the process to follow but the tools to use, artifacts to look for, artifacts meaning, and provide sample data to practice on. Well, I have not been able to locate a resource to my liking addressing malware examinations. So I decided to create one and what I just describe is a glimpse of the book I’m starting at some point next year.

My book is on hold because my current focus is on another endeavor. I am developing the Malware Analysis course for Champlain College’s Master of Science in Digital Forensic Science program. The course will cover a range of topics from malware fundamentals to memory forensics to malware forensics to malware analysis (reversing). It is an honor to be a part of Champlain College and I’m looking forward to do everything I can to put together a great course for an outstanding program.

Lastly, I am starting to take on additional malware responsibilities with my employer. jIIr has always been a personal blog and I never discuss the work I do for my employer. I will continue to have this boundary so I won’t elaborate on what my responsibilities are besides hinting at the fact malware will take up more of my time at my job.

This malware convergence means I will be living and breathing malware everyday and all day for the upcoming year. The little personal time I may have for research is going to be spent on different aspects of the malware issue. As a result, jIIr is going to be more focused on topics related to malware. I will try my best to mix in other content about DFIR or security but to be honest I don’t know if I will have the time. The perfect storm has arrived and I hope you stick around to ride it out.

Merry Christmas and Happy New Year.


Extracting ZeroAccess from NTFS Extended Attributes

Tuesday, December 11, 2012 Posted by Corey Harrell 13 comments
This past week I was reading a paper about the ZeroAccess Trojan when a section about a clever data hiding technique caught my eye. The paper was Sophos’s The ZeroAccess Botnet: Mining and Fraud for Massive Financial Gain and I’m referring to the Services.exe section which stated (on page 6):

"If installed on Windows Vista or higher ZeroAccess will attempt to patch the Windows file services.exe. A subroutine inside services.exe is overwritten with shellcode that is carried inside the ZeroAccess dropper.

A large amount of binary data is also written to the NTFS Extended Attributes of services.exe. Extended Attributes are a feature of NTFS similar in nature to Alternate Data Streams where extra information about the file can be stored on the file system. ZeroAccess uses this feature to hide a whole PE file as well as shellcode that loads the PE file. The overwritten subroutine in services.exe reads in all the data from the Extended Attributes and executes it. The shellcode then loads and executes the embedded PE file. This file is a DLL that has equivalent functionality to the main component, so the services.exe modifications provide a backup means for the bot to function if the two main components are discovered and removed."

I was already fascinated about the Trojan’s use of two separate DLLs to maintain persistence but what I read opened my eyes. ZeroAccess leveraged a third DLL for persistence that was hidden inside the NTFS Extended Attributes. A Google search lead me to a third article by Symantec - Trojan.Zeroaccess.C Hidden in NTFS EA. I then remembered a few months back someone from the Yahoo Win4n6 group posted the write-up ZeroAccess – From Rootkit to Nasty Infection – which also discussed ZeroAccess hiding data inside NTFS Extended Attribute. At the time, I read the HitmanPro article and bookmarked it amongst my malware references but I didn’t give it too much thought. Now my eyes are open and the use of the NTFS Extended Attribute had my full attention. A few thoughts were running through my head (yes in this order)

     1. This is a really cool technique

     2. The articles don’t mention how to extract the data from the Extended Attribute. I wonder how you can do it.

     3. Hiding data in the Extended Attribute is brilliant since antivirus software might not check there. Come to think about it most digital forensic tools don’t parse the data inside Extended Attributes either.

     4. Wait a second; I never look at the NTFS Extended Attributes during my examinations. I need to come up with a way to do it and add it to my examination process. It could be a check underneath my Malware Searches examination step.

     5. Alight, this is definitely cool.

In this post I’m providing answers to all the questions that were racing through my mind. The post is broken up into the sections:

     - What Are NTFS Extended Attributes

     - My Testing Environment

     - Extracting Data from NTFS Extended Attributes

     - Extracting ZeroAccess from NTFS Extended Attributes

     - Locating Other ZeroAccess Files on System

What Are NTFS Extended Attributes

The NTFS filesystem is the default for the Microsoft Windows server operating systems as well as Windows 2000, XP, Vista, and 7. The Master File Table ($MFT) is the component in NTFS containing information about all the files and folders on the volume. “Every file and directory has at least one entry in the table, and the entries by themselves are very simple.” The entry basically consists of a header and attributes. Two attributes are the $EA index and $EA_INFORMATION which are the NTFS Extended Attributes.

The File System Forensic Analysis book shows the $EA_INFORMATION type identifier as 208 and $EA identifier as 224 (credit goes to Harlan for this reference). The book further stated both attributes are “used for backward compatibility with OS/2 applications (HPFS).” In addition, the book Windows Internals, Part 2: Covering Windows Server 2008 R2 and Windows 7 stated “extended attributes are name/value pairs and aren’t normally used but are provided for backward compatibility with OS/2 applications”. The references provide a little more clarity about what the author of ZeroAccess is doing. They are using hardly used $MFT attributes meant for backward compatibility as a place to hide data. The cool factor with this technique went up a few notches.

Testing Environment

Before diving into the answers to all my questions I wanted to provide information about my testing environment. Knowing the testing environment makes it easier for others to see exactly what I did and how to replicate my testing. For those looking for the “good stuff” skip ahead to the section Extracting Data from NTFS Extended Attributes.

Finding the ZeroAccess Sample

In all the articles about ZeroAccess using the NTFS Extended Attributes I noticed one commonality; this technique was used in an updated version of the Trojan. Check out the commonality: HitmanPro posted their write up on June 25, 2012, Symantec did theirs on August 14, 2012, and Sophos report was released in September 2012. Furthermore, Sophos stated in their opening sentence “since our last paper on ZeroAccess, The ZeroAccess Rootkit, its authors have made significant changes.” The point was crystal clear, I needed to find a recent ZeroAccess sample in order to find one leveraging the $EA hiding technique.

I searched for samples in the Virus Share malware repository as you will see why shortly. A generic search for “zeroaccess” wasn’t to helpful since it resulted in 6,056 results. I needed a more focused search so I turned to Symantec’s detection Trojan.ZeroAccess.C. It reduced my search results to 9 samples.

A nice feature about Virus-Share is it provides links to each sample’s VirusTotal’s report. I used the VT report to further narrow down my samples. On VirusTotal’s Additional Information section, I first looked to see when each sample was first seen.

Remember the commonality with the articles? I only wanted to focus on samples first seen within the past few months. The second check I did on the Additional Information section was to look at the TrID output to determine what samples were executables as opposed to DLLs. Working with an exe makes it a little easier for fast execution.

I narrowed my samples down to five based on the above checks. Not every ZeroAccess Trojan will modify the services.exe and store binary data in the NTFS Extended Attribute. So I started executing one sample after another to see if any modified the services.exe MFT record. I didn’t do any dynamic analysis; I pretty much just ran a sample and then looked at the services.exe MFT record to see if the Extended Attributes were added. On the third sample I hit pay dirt. The sample MD5 hash b437274492e215c25f96711d04b44050 (SHA256 658817f5f7722506868d9f717ee19b276fcab0d0ecac071d5d92a4178fdeb5b3) leveraged the NTFS Extended Attributes.

Side note: I mentioned in the Win4n6 group I was looking for ZeroAccess samples that used the NTFS Extended Attributes. Stefan replied with not only the MD5 hash c6e73a75284507a41da8bef0db342400 but links to the article ZeroAccess - new steps in evolution and the ThreatExpert Report. This sample is the next one I’m going to check out.

Configuring my Test System

The Sophos report indicated the services.exe is only patched if ZeroAccess is installed on a system with Windows Vista or higher. I selected for my test system Windows 7 Ultimate 32 bit which I was running inside VMware. I used a fresh install and the only configuration change I made was to disable the User Account Control. I wanted to avoid making ZeroAccess elevate its privileges. I also installed the program Capture.bat as a quick way to see changes made to the file system.

Extracting Data from NTFS Extended Attributes

I had to answer my first question before I could go forward with any testing. How do I extract the binary data from the NTFS Extended Attributes? I reached out to the Win4n6 group for suggestions and Brian Carrier pointed me to the promise land. He suggested I used the Sleuthkit; specifically istat to see what attributes a MFT record has and icat to dump the data in an attribute. The process needed to extract data stored inside NTFS Extended Attributes with TSK is as follows:

Note: the TSK tools can be ran against a forensic image or a mounted drive. My examples throughout the post are against a mounted drive (\\.\PHYSICALDRIVE#) but the path to a forensic image could be used instead.

1. Identify the starting sector of the partition where services.exe is located. Typically, the first sector for Vista and 7 is 2048 (XP is 63). The TSK tool to use is mmls and the command is:


2. Identify the inode number for the C:\Windows\System32\services.exe file. The TSK tool to use is ifind and the command is:

ifind -o 2048 -n "Windows/System32/services.exe" \\.\PHYSICALDRIVE#

Command explanation: the –o switch is to specify the sector offset that was discovered with mmls and the –n switch is the file name to get the inode for.

3. Review the attributes associated with the MFT record for C:\Windows\System32\services.exe. The TSK tool to use is istat and the command is:

istat -o 2048 \\.\PHYSICALDRIVE3 12345

Command explanation: the –o switch is the sector offset and the 12345 is the place where the inode number goes. The attributes of interest are $EA_INFORMATION (208) and $EA (224).

4. If present, make note of the NTFS Extended Attributes. In istat’s output, next to the attribute name will be a value inside parentheses. i.e. the value in my test appeared as $EA (224-4)

5. Dump the contents from the $EA and $EA_INFORMATION and redirect it to a file. The TSK tool to use is icat and the commands are:

icat -o 2048 \\.\PHYSICALDRIVE# 12345-208-# > EA_INFO.txt
icat -o 2048 \\.\PHYSICALDRIVE# 12345-224-# > EA.txt

Command explanation: the –o switch is the sector offset and the number at the end is the inode number with the attribute value added. The 208-# dumps $EA_INFORMATION and 224-# dumps $EA.

The above process can be used to either read a MFT’s record attributes or dump the data stored in those attributes.

Extracting ZeroAccess from NTFS Extended Attributes

To completely answer my first question about how to extract the ZeroAccess Trojan from NTFS Extended Attributes I actually had to do it. This is what I ended up doing:

     - Determined what a clean MFT services record looks like
     - Located an infected MFT services record
     - Extracted ZeroAccess from the MFT services record
     - Created the ZeroAccess binary

What Does a Clean MFT Services.exe Record Look like?

It’s always good to know what normal looks like so it’s easier to see what is abnormal. This was my thinking and why I first looked at a clean MFT services.exe record. Here’s what I did and what it looked like. I highlighted in blue values of interest.

1. Confirmed the starting sector for the partition.


DOS Partition Table
Offset Sector: 0
Units are in 512-byte sectors

Slot Start End Length Description
00: Meta 0000000000 0000000000 0000000001 Primary Table (#0)
01: ----- 0000000000 0000002047 0000002048 Unallocated
02: 00:00 0000002048 0020969471 0020967424 NTFS (0x07)
03: ----- 0020969472 0020971519 0000002048 Unallocated

2. Identified the inode number for the C:\Windows\System32\services.exe file.

ifind -o 2048 -n "Windows/System32/services.exe" \\.\PHYSICALDRIVE2


3. Reviewed the attributes associated with the C:\Windows\System32\services.exe MFT record. Notice there are no $EA or $EA_INFORMATION attributes listed under the Attributes section.

istat -o 2048 \\.\PHYSICALDRIVE2 19211

MFT Record Header Values:
Record: 19211 Sequence: 1
$LogFile Sequence Number: 34894400
Allocated File
Links: 2

Flags: Archive
Owner ID: 0
Security ID: 450 ()
Created: 2009-07-13 19:11:26 (Eastern Daylight Time)
File Modified: 2009-07-13 21:14:36 (Eastern Daylight Time)
MFT Modified: 2012-12-06 11:54:31 (Eastern Standard Time)
Accessed: 2009-07-13 19:11:26 (Eastern Daylight Time)

$FILE_NAME Attribute Values:
Flags: Archive
Name: services.exe, services.exe
Parent MFT Record: 7150 Sequence: 1
Allocated Size: 0 Actual Size: 0
Created: 2012-12-06 11:54:31 (Eastern Standard Time)
File Modified: 2012-12-06 11:54:31 (Eastern Standard Time)
MFT Modified: 2012-12-06 11:54:31 (Eastern Standard Time)
Accessed: 2012-12-06 11:54:31 (Eastern Standard Time)

Type: $STANDARD_INFORMATION (16-0) Name: N/A Resident size: 72
Type: $FILE_NAME (48-4) Name: N/A Resident size: 90
Type: $FILE_NAME (48-2) Name: N/A Resident size: 90
Type: $DATA (128-3) Name: N/A Non-Resident size: 259072 init_size: 259072
750372 750373 750374 750375 750376 750377 750378 750379
750380 750381 750382 750383 750384 750385 750386 750387
750388 750389 750390 750391 750392 750393 750394 750395
750396 750397 750398 750399 750400 750401 750402 750403
750404 750405 750406 750407 750408 750409 750410 750411
750412 750413 750414 750415 750416 750417 750418 750419
750420 750421 750422 750423 750424 750425 750426 750427
750428 750429 750430 750431 750432 750433 750434 750435

Located an Infected MFT Services.exe Record

The clean C:\Windows\System32\services.exe file only had four attributes listed. The $STANDARD_INFORMATION (16-0), $FILE_NAME (48-4), $FILE_NAME (48-2), and $DATA (128-3) attributes. Here’s what an infected services.exe MFT record looks like and what I did. I highlighted in blue values of interest and items related to the infection in red.

1. Confirmed the starting sector for the partition.


DOS Partition Table
Offset Sector: 0
Units are in 512-byte sectors

Slot Start End Length Description
00: Meta 0000000000 0000000000 0000000001 Primary Table (#0)
01: ----- 0000000000 0000002047 0000002048 Unallocated
02: 00:00 0000002048 0020969471 0020967424 NTFS (0x07)
03: ----- 0020969472 0020971519 0000002048 Unallocated

2. Identified the inode number for the C:\Windows\System32\services.exe file.

ifind -o 2048 -n "Windows/System32/services.exe" \\.\PHYSICALDRIVE2


3. Reviewed the attributes associated with the C:\Windows\System32\services.exe MFT record.

istat -o 2048 \\.\PHYSICALDRIVE2 42756

MFT Record Header Values:
Record: 42756 Sequence: 1
$LogFile Sequence Number: 98696063
Allocated File
Links: 1

Flags: Archive
Owner ID: 0
Security ID: 483 ()
Last User Journal Update Sequence Number: 17321736
Created: 2009-07-13 19:11:26 (Eastern Daylight Time)
File Modified: 2009-07-13 21:14:36 (Eastern Daylight Time)
MFT Modified: 2012-12-06 17:18:05 (Eastern Standard Time)
Accessed: 2009-07-13 19:11:26 (Eastern Daylight Time)

$FILE_NAME Attribute Values:
Flags: Archive
Name: services.exe
Parent MFT Record: 1802 Sequence: 1
Allocated Size: 0 Actual Size: 0
Created: 2009-07-13 19:11:26 (Eastern Daylight Time)
File Modified: 2012-12-06 17:18:05 (Eastern Standard Time)
MFT Modified: 2012-12-06 17:18:05 (Eastern Standard Time)
Accessed: 2012-12-06 17:18:05 (Eastern Standard Time)

Type: $STANDARD_INFORMATION (16-0) Name: N/A Resident size: 72
Type: $FILE_NAME (48-2) Name: N/A Resident size: 90
Type: $DATA (128-5) Name: N/A Non-Resident size: 259072 init_size: 259072
618 619 620 621 622 623 624 625
626 627 628 629 630 631 632 633
634 635 636 637 638 639 640 641
642 643 644 645 646 647 648 649
650 651 652 653 654 655 656 657
658 659 660 661 662 663 664 665
666 667 668 669 670 671 672 673
674 675 676 677 678 679 680 681
Type: $EA_INFORMATION (208-3) Name: N/A Resident size: 8
Type: $EA (224-4) Name: N/A Non-Resident size: 23404 init_size: 23404
346 347 348 349 350 351

Extract ZeroAccess from MFT Services Record

The infected MFT services.exe record had a few different changes. The inode number for C:\Windows\System32\services.exe changed from 19211 to 42756. In addition, the attributes now listed the NTFS Extended Attributes: $EA_INFORMATION (208-3) and $EA (224-4). The ZeroAccess binary data can now be extracted using the attribute values shown with istat. Here’s how I extracted the data.

4. Extracted the binary data from the MFT record for C:\Windows\System32\services.exe for both the $EA_INFORMATION and $EA attributes.

icat -o 2048 \\.\PHYSICALDRIVE2 42756-208-3> icat_services_$EA-INFORMATION.bin
icat -o 2048 \\.\PHYSICALDRIVE2 42756-224-4 > icat_services_$EA_binary.bin

Create the ZeroAccess Binary

The Sophos report indicated the ZeroAccess binary data stored in the NTFS Extended Attribute is shellcode and a DLL. This means I had to separate the two in the dumped data; my focus was only on the DLL. There was very little data stored in the $EA_INFORMATION attribute while the majority of the data – including the DLL – was in the $EA attribute. To rebuild the DLL I opened the extracted data in a Hex editor and looked for for a PE file’s characteristics. I was looking for the MZ file signature and the MS-DOS message.

I located the MZ signature at offset 1684 so I copied out the binary data from offset 1684 to the end of the file. The resulting file was SHA256 ee14dcd20b2ee118618e3a28db72cce92ccd9e85dd8410e02479d9d624934b13 which was detected as the ZeroAccess Trojan.

Locating Other ZeroAccess Files on System

Locating the infected services.exe file and extracting the binary data from the NTFS Extended Attributes only addresses one part of the infection. ZeroAccess drops other files on a system and I wanted to find these as well. However, I didn’t want to cheat by looking at my Capture.bat log file. I wanted to verify how a system timeline worked by using the services.exe as a starting point to find the other malicious files.

Timelines are my go to tool when I’m trying find files associated with an infection. A timeline can reveal other activity occurring on a system around a certain time of interest. In this case, I was interested in seeing the activity around the time when the services.exe file was last modified as shown below. (the timeline was created with AnalyzeMFT).

The timeline showed the services.exe file was modified on 12/06/12 at 18:05:09. The activity beforehand included the creation of files and folders in both the C:\Windows\Installer and C:\Users\Lab\AppData\Local folders. The file named n in both locations is the ZeroAcess Trojan.


Storing data inside the NTFS Extended Attributes is a clever way to hide data. Based on the reports I read, ZeroAccess started to use this technique within the last year. So far it appears as if this is not a commonly used technique to hide data among malware. The only reports I could find only talked about ZeroAccess. However, in time I would not be surprised to see other malware families trying to use NTFS Extended Attributes. To see why just think about these two questions: how many tools are checking the NTFS Extended Attributes for every file and how many DFIR practitioners and IT staff are actually aware that malware can be hidden there? If I was a betting man I’d put my money on both answers being “very few”. My eyes are opened to this hiding technique and I added a check underneath my Malware Searches examination step to account for it. If I ever need to determine if something is leveraging NTFS Extended Attributes then this is the process I will use.

1. Parse the MFT so that NTFS Extended Attributes are shown for every file. One tool to use is AnalyzeMFT with the command

analyzeMFT.py -f $MFT -o parsed_mft.txt

Import analyzeMFT’s output into Excel or Calc (output is comma delimited format). Apply a sort on the $EA attribute being true to show every file with a NTFS Extended Attribute.

2. Locate the files’ of interest MFT records. AnalyzeMFT’s output contains this information.

3. Identify the partition’s starting sector. One tool to use is TSK’s mmls with the command:


4. Review the attributes associated with any files of interest. One tool to use is TSK’s istat with the command

istat -o 2048 \\.\PHYSICALDRIVE3 12345

5. Make note of the NTFS Extended Attributes $EA_INFORMATION and $EA. In istat’s output, next to the attribute name will be a value inside parentheses.

6. Dump the data from the $EA and $EA_INFORMATION for closer inspection. Use TSK’s icat with the commands:

icat -o 2048 \\.\PHYSICALDRIVE# 12345-208-# > EA_INFO.txt
icat -o 2048 \\.\PHYSICALDRIVE# 12345-224-# > EA.txt

Happy Hunting

NTOSBOOT Prefetch File

Wednesday, December 5, 2012 Posted by Corey Harrell 9 comments
Knowing the programs that executed on a system can answer numerous questions. The answers can help on a range of cases from acceptable use policy violations to investigations to intrusions to malware. One program execution artifact is prefetch files which have been well documented including in the article Decoding Prefetch Files for Forensic Purposes and on the Prefetch Wiki page. The purpose of this post is to explore the NTOSBOOT prefetch file and how it is relevant for malware investigations.

What is the NTOSBOOT Prefetch File

The Windows operating system enables prefetching to make system boots or applications startups faster. Windows Internals, Part 2: Covering Windows 2008 Server R2 and Windows 7 states “the prefetcher tries to speed the boot process and application startup by monitoring the data and code accessed by boot and application startups and using that information at the beginning of a subsequent boot or application startup to read in the code and data”. Prefetch files are what store the information required for faster startups.

The NTOSBOOT prefetch file stores the information related to the boot process. The information in this prefetch file reflects the files accessed during system startup. Specifically, the files accessed, according to the Windows Internals, “from system start through the 30 seconds following the start of the user’s shell (typically Explorer) or, failing that, up through 60 seconds following Windows service initialization or through 120 seconds, whichever comes first”.

Relevance for Malware Investigations

The NTOSBOOT prefetch file stores information about the files accessed during the boot process and in some cases 30 seconds following a user logging onto a system. Remember the Rootkit Paradox, malware wants to hide but it must run. If a piece of malware runs during the boot process then there will be a reference for the malware in the NTOSBOOT prefetch file. To illustrate this point I examined a NTOSBOOT prefetch file to show how it contains traces of malware execution. (side note: to view the file handles in prefetch files one could use Strings or Harlan’s pref.pl)

The NTOSBOOT prefetch file in question came from a system I infected last year by opening the attachment in a NYS Department of Motor Vehicles Uniform Traffic Ticket email. Looking through the file handles for any unusual file paths (files in temporary folders, unusual file names, etc) I came across three suspicious files as shown below.

The first file 17F7FFF4.COM was suspicious since the file was located in the All Users temporary folder. The second file KB961710.exe was suspicious because Windows updates are not stored in the application data folders. The last file SVCHOST.EXE was suspicious since not only was it located in a temp folder but the svchost.exe file is normally located in the Windows\System32 folder. I located these files by solely reviewing the file handles referenced in the NTOSBOOT prefetch file and the screenshot below confirms my suspicions.


Program execution artifacts are vital when examining a system infected with malware. Despite malware’s best efforts to hide on a system at some point for them to do their jobs they have to run. When malware eventual runs there will be traces of its execution left on a system which can be used to find its hiding spot. The NTOSBOOT prefetch file is one such artifact and the file handle information will reveal what’s hiding on a system.

Different Take on the Rootkit Paradox

Friday, November 30, 2012 Posted by Corey Harrell 1 comments
Jesse Kornblum’s paper “Exploiting the Rootkit Paradox with Windows Memory Analysis” explains the predicament Rootkits find themselves in. The predicament is:

        1. They want to remain hidden.

        2. They need to run.

Jesse’s paper goes into detail about this paradox so I won’t. The main point is Rootkits want to remain hidden on a system but they need to run on an operating system. If an operating system can find the Rootkit then so can an examiner. The paradox applies to all kinds of malware from data stealers to remote access Trojans to droppers.

I’ve been thinking about the Rootkit Paradox and there is another aspect to it that is important for examiners to understand. The second predicament is:

        1. They need to run.

        2. They want to remain hidden

In this case the “they” in the need to run is a piece of malware while the “they” in the want to remain hidden are Rootkits. Basically, a program needs to run in order to hide a Rootkit on a system. The program could be the Rootkit itself or a different piece of malware such as a dropper or installer. When a program runs on the system it creates artifacts showing it executed. An examiner could then look at those artifacts along with changes made to the file system (files/folders creations and modifications) to determine where the Rootkit or its components are hiding. Again this predicament applies to all kinds of malware.

The Rootkit Paradox is alive and well, and can be leveraged to find malware hiding on a system.

To Whom It May Concern

Tuesday, November 20, 2012 Posted by Corey Harrell 1 comments
This is an open letter to a person I will never get to meet. We will never exchange greetings nor will I ever know their name or identity. I had to settle for an open letter since I’m unable to give them a proper thank you. Please don’t misunderstand my attempt at thanking them since I’m truly sincere. This is not an attempt at humor nor is it an attempt to condescend them. This is my thank you; thanking them for infecting my system so many years ago.

To Whom It May Concern,

As the holidays are approaching it’s a time of reflection. I’ve been reflecting on my “Journey into Incident Response.” There have been numerous people who helped me along the way; people who influenced me and helped make me into the Digital Forensic and Incident Response (DFIR) practitioner I am today. Reflecting on all these people I can’t help but think how you impacted my journey. You may not even be aware of the impact you had on me, but your actions are what opened my eyes to a whole new world and made me take the first step of my journey.

At the time I was in a position doing two different responsibilities. I was performing vulnerability assessments against organizations, testing networks to find vulnerabilities. At other times I was performing digital forensic examinations to determine if someone was committing fraud. I saw my two responsibilities as separate; as duties that didn’t blend together. My perspective changed when I saw your handy work appear on my computer, which was a rogue security program holding my computer hostage. That one single event is what started me on my journey; my journey of leveraging my offensive security background to improve my DFIR knowledge and skills when investigating security incidents.

I never attempted malware forensics before this, but I wanted to know if I could figure out how you were able to install your malware on my box. I successfully traced your malware to a PDF targeting an Adobe Reader vulnerability that was delivered through a malicious advertisement served up by Yahoo’s website. Some may say it was luck, but I beg to differ. I knew that in order to get a remote code execution, an exploit had to be used. The answer was clear as day once I found the PDF that was created on the system around the same time as the malware.

I know I was not even a blip on the radar screen; maybe just an IP address showing a successful install. You opened my eyes to a whole new area; an area where the offensive side of security meets the investigative side. Where knowing how to attack systems is as beneficial as knowing what artifacts are created by those attacks. How this combination of skills and knowledge can be used to obtain intelligence to help better secure organizations and people. I know I would have come to this conclusion eventually, but your actions helped me see it sooner rather than later.

My passion for information security, my motivation to learn, and my drive to share my knowledge with others took care of the rest. Little did you know you were awakening a sleeping giant. I don’t consider myself a giant but it’s the only words that come to mind when looking at the aftermath of the infection. I dedicated myself to learning and researching how to investigate security incidents. Eventually it evolved into me using my knowledge and skills to help others investigate security incidents. I started my blog as one avenue to share what I have learned. I try to help my colleagues become better DFIR investigators through presentations and sharing my thoughts. I use my skills to help home users become better equipped to secure their computers through education about what holes to close after I remove malware from their systems. I help organizations by providing them with intelligence to improve their security by analyzing the systems impacted by attacks. I am developing a graduate course to help strengthen the ranks of DFIR practitioners capable of investigating malware incidents. I’m even considering authoring a book to reach a larger audience about malware forensics. I truly wanted to show the chain of events to illustrate why it’s as if a sleeping giant was disturbed.

I bet you have never heard a user you infected say thank. I will be the first; the first to say thank you for infecting my system so many years ago. Thank you for opening my eyes to a whole new world, sooner rather than later. Thank you for showing me the first step I needed to take to become your adversary.

Finding An Infection Vector After IT Cleaned the System

Wednesday, November 7, 2012 Posted by Corey Harrell 12 comments
Almost every “CSI” episode begins the same way. An attack took someone’s life, first responders secured the crime scene, and then the main characters show up to start processing a well preserved scene. The technological equivalent of this is the following: an attack compromises a system, first responders image the system’s memory before immediately powering the system down, and then a forensicator shows up to process the scene. This is an ideal situation but life is not always ideal. Actions taken by users and first responders do not always leave a well preserved scene. Anti-virus scans are ran, files are deleted, temporary folders are emptied, programs are installed/removed, system restore points/volume shadow copies are deleted, or the system is left running resulting in data being altered. Only after all these actions is the forensicator consulted and asked to figure out how the compromise occurred. Needless to say conducting the analysis is more difficult and time consuming but it is not impossible. There still may be artifacts left on the system providing clues to what happened.

In order to demonstrate this, I setup a simulation where I purposely infected a Windows XP system and then I mimicked actions someone would take to remove the infection. Afterwards I examined the system to see what artifacts I could find. I wanted to simulate a real life scenario so I performed the following common troubleshooting techniques administrators do when trying to “clean” a system and get it back into working order as quickly as possible.

        • McAfee antivirus scans were conducted and any detections were cleaned
        • All temporary folders’ contents were deleted
        • All prefetch files were deleted
        • All recycle bins were emptied
        • All system restore points were deleted
        • Avast! was installed and a scan was conducted

The actions may be common troubleshooting techniques but I picked them for a different reason. All of those actions potentially destroy vital information that could help determine how an infection occurred. Antivirus software deleting malware not only removes the suspicious files from the system but it also destroys their filesystem metadata. This metadata can narrow down the timeframe to when the infection occurred. Deleting the files in the Windows\Prefetch folder makes it harder to determine what programs executed on the system. Deleting files in the Windows temporary, user profiles’ temporary, and Internet browser folders removes any secondary artifacts –such as exploit artifacts – that can provide additional information about an event. Emptying the recycle bin ensures the files are actually deleted from the system. Windows System Restore Points are an interesting artifact because they contain backup copies of registry hives and Windows system files. Deleting the System Restore Points destroys the historical information they contain. Lastly, installing and running additional anti-virus software makes more changes to the system and potentially alters or deletes information beneficial to an analysis.

Potential Artifacts

The common troubleshooting techniques destroyed some of the information I look for when faced with a malware infected system. Despite those actions there is still data left on a system providing clues about how the infection occurred. Based on the actions taken, four potential areas containing information are:

        1. Host Based Logs
        2. NTFS Artifact
        3. Registry Artifacts
        4. System Timeline

Host Based Logs

Antivirus software typically records installation and other system activities in text logs. The location of these text log files is specific to each antivirus product. One method used to identify the installed antivirus products is the Uninstall Registry key in the Software hive[1]. Afterwards, Google searches on the products can show the where the folders containing logs are located. I reviewed the Uninstall Registry key on the infected system using RegRipper and found the following:

Sun Apr 8 04:49:07 2012 (EDT)
      avast! Free Antivirus v.7.0.1426.0

Sat Apr 7 10:52:52 2012 (EDT)
      McAfee VirusScan Enterprise v.8.6.0

The above information showed there were two installed antivirus products; they were McAfee antivirus and Avast!. The Google searches I performed showed me where both products store their logs on a Windows XP system. In addition to these logs, antivirus products activity may also be recorded in the Windows events logs. I examined both the antivirus and Windows events logs looking for any information about the infection.

The McAfee logs are located in the DesktopProtection folder located under “Documents and Settings\All Users\Application Data\McAfee\”[2]. Two specific logs of interest were the OnAccessScanLog and OnDemandScanLog. The OnAccessScanLog log records information regarding McAfee continuously monitoring a system. The second log – OnDemandScanLog – records information regarding scans conducted against a system. The OnAccessScanLog did not contain any entries for the malware. However, the OnDemandScanLog contained entries outlining what had been deleted, cleaned, or quarantined by McAfee. Below were some entries found:

• 4/8/2012 4:06:46 PM (EDT) Deleted corey C:\SYSTEM VOLUME INFORMATION\_RESTORE{3F806DB1-464B-46B0-B724-4376EC868222}\RP6\A0003833.EXE BackDoor-AMQ(Trojan)

• 4/8/2012 4:06:46 PM (EDT) Deleted corey C:\SYSTEM VOLUME INFORMATION\_RESTORE{3F806DB1-464B-46B0-B724-4376EC868222}\RP6\A0003834.COM BackDoor-AMQ(Trojan)

• 4/8/2012 4:06:49 PM (EDT) Deleted corey C:\WINDOWS\SVCHOST.EXE BackDoor-AMQ(Trojan)

• 4/8/2012 4:06:50 PM (EDT) Deleted corey C:\WINDOWS\MSAGENT\MSQGIX.COM BackDoor-AMQ(Trojan)

• 4/8/2012 4:06:50 PM (EDT) Deleted corey C:\WINDOWS\SYSTEM32\MSMHXY.COM BackDoor-AMQ(Trojan)

The Windows Application Event log - AppEvent.Evt – collaborated the information in the OnDemandScanLog log. There were numerous Event IDs 258 showing McAfee deleted numerous files detected as BackDoor-AMQ (Trojan) on 4/8/2012 4:06:50 PM (EDT). The OnDemandScanLog and Windows Application Event logs revealed that the “corey” user account conducted a McAfee On-demand scan around 4/8/12 4:06 PM (EDT). The scan deleted the files svchost.exe, msqgix.com, and msmhxy.com from different locations in the Windows folder while files with the same extensions were deleted from a System Restore Point. The last piece of information indicated that McAfee detected the files as the BackDoor-AMQ Trojan. I searched McAfee’s website for additional information about BackDoor-AMQ[3] but it wasn’t useful without having access to the actual malware or their hashes.

I proceeded to examine the Avast! logs located in the Log folder under “Documents and Settings\All Users\Application Data\AVAST Software\Avast”. I was looking at the names of the files in the folder when I noticed one named Setup.log. The Setup.log shows the information related to installation of Avast! and the log’s first entry stated “Started: 08.04.2012, 16:46:02”. Later on in the Setup.log I found an entry showing Avast! antivirus was installed at 4/08/12 4:49:06 PM (EDT). I wanted to correlate the information with the Windows event log. The System Event log - SysEvent.Evt – Event ID 7035 showed at 4/08/12 4:48 PM (EDT) the Windows installer started. The first entries for the Avast! in the System Event log occurred one minute later (4:49 PM (EDT)) when numerous Avast! services were started (Event IDs 7035). Something I found interesting was that the Avast! services were started under the context of the local administrator user account.

I continued looking at the other Avast! text log files in the folder and noticed that the logs starting with asw were the ones containing the results of any scans conducted against the system. The Avast! logs did not contain any entries related to files being deleted, cleaned, or quarantined on the test system.

The examination of the host based logs provided some indicators about what occurred on the system. There were numerous suspicious files (svchost.exe, msqgix.com, and msmhxy.com) located within the Windows folder. These files were detected as BackDoor-AMQ Trojans followed by being deleted when the “corey” user account conducted a McAfee antivirus scan. I knew my best bet at finding artifacts showing how the system was infected was to identify when those files first appeared or executed on the system. I turned my attention to the NTFS artifacts to see what information was available.

NTFS Artifact

When antivirus products delete or quarantine files the filesystem may still maintain metadata about those files. One piece of information that can be pulled from this metadata is timestamps; this can be valuable to the analyst, as it helps identify the timeframe of when the system first became infected. One NTFS artifact[4] that may shed light about an infection after a system is cleaned is INDX files.

INDX files contain records for each file within a directory. Each record contains information about the file including: filename, file size, and timestamps[5]. The records in INDX files may remain after files are deleted from a system[6]. This behavior makes INDX files an excellent artifact to provide information about files deleted from the system in attempts to remove malware. An analyst can use Willi Ballenthin’s INDXParse python script to parse these artifacts. On the test system the McAfee antivirus logs indicated the following files were deleted:

        • A0003833.EXE and A0003834.COM from RP6 (System Restore Point)
        • SVCHOST.EXE from the C:\Windows folder
        • MSMHXY.COM from the C:\Windows\System32 folder
        • MSQGIX.COM from the C:\Windows\MSAGENT folder

I was interested to see if either the Windows, System32, or Msagent folders’ INDX files contained any timestamps for the svchost.exe, msmhxy.com, and msqgix.com files. I examined the Windows and System32 folders’ INDX files but it didn’t provide any information about the timestamps I was looking for. However, the Msagent folder’s INDX file contained timestamps for the msqgix.com file.

        • Filename: msqgix.com (slack at 0x5c0)
        • Modified Time: 2012-04-08 4:06:50.390625 PM (EDT)
        • Accessed Time: 2012-04-08 4:06:50.328125 PM (EDT)
        • Changed Time: 2012-04-08 4:06:50.390625 PM (EDT)
        • Created Time: 2004-08-04 12:00:00

Correlating the above timestamps to the information I learned from examining the host based logs shows the timestamps are around the time when McAfee deleted the file. I also checked the Prefetch folder’s INDX file hoping to find information about program execution but it did not provide any useful information about the attack. This time around the INDX files did not provide any new information about how the attack occurred but it is an NTFS artifact to keep in mind with respect to files that may have been deleted.

I still needed to identify the timeframe of when the infection occurred since I didn’t get the information from the host based logs and INDX files. I know when malware executes it may change system configuration settings in the Registry which is where I looked next.

Registry Artifacts

When an administrator takes actions to remove malware from a system not only are important files deleted but many times, those files’ metadata is lost as well. Not having access to the metadata makes it tougher to identify the timeframe of when the system was initially infected. However, if the malware makes changes to the Registry then the Last Write times associated with modified registry keys modify can help fill in some of these gaps. Different methods can be used to locate the information stored in the Registry, from checking common keys used by malware to performing keyword searches. The McAfee log file provided names of three files of interest that were used in a keyword search. The following list provides the results of these searches.

1. C:\Windows\SVCHOST.EXE Search Hit 1
     a. Last Write Time: 2012/04/08 3:06:31 PM (EDT)
     b. Key: HKLM\System\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
     c. Data: C:\Windows\svchost.exe

2. C:\Windows\System32\MSMHXY.COM Search Hit 1
     a. Last Write Time: 2012/04/08 3:06:33 PM (EDT)
     b. Key: HKLM\Software\Microsoft\Active Setup\Installed Components\{42CE4021-DE03-E3CC-EA32-40BB12E6015D}
     c. Name: Stubpath
     d. Data: C:\Windows\System32\MSMHXY.COM

3. C:\Windows\MSAGENT\MSQGIX.COM Search Hit 1
     a. Last Write Time: 2012/04/08 3:06:33 PM (EDT)
     b. Key: HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
     c. Name: COM Service
     d. Data: C:\Windows\MSAGENT\MSQGIX.COM

4. C:\Windows\MSAGENT\MSQGIX.COM Search Hit 2
     a. Last Write Time: 2012/04/08 3:06:33 PM (EDT)
     b. Key: HCU\ntuser-corey\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
     c. Name: COM Service
     d. Data: C:\Windows\MSAGENT\MSQGIX.COM

I found the Registry keyword searches enlighten because it showed the changes the malware made when it executed. The earliest timestamp - 2012/04/08 3:06:31 PM (EDT) – is when the firewall configuration was changed to make the svchost.exe file an authorized application. The search hits also identified how the malware remains persistent; the msqgix.com file was added to the Run key in the Software and "corey" user account hives. In the past, I’ve seen when malware infects a system it adds a persistence mechanisms to both the logged on user account NTUSER.DAT and to either the System or Software hives. It appears the malware did this by adding entries to two different Run keys. I thought the “corey” user account was not only involved with running the McAfee antivirus scan but might have been logged on when the infection occurred. Lastly, all the Registry keys Last Write times were 04/08/2012 3:06 PM (EDT) and this provided me with the first indicator to when the infection may have occurred.

I wanted to see if any programs were run by the “corey” user account around the 3:06 PM (EDT). I ran RegRipper with the userassist plug-in against the “corey” user account’s NTUSER.DAT hive which showed the following activity (I adjusted the time from Coordinated Universal Time to Eastern Daylight Time).

Sun Apr 8 3:06:21 2012 PM (EDT)
     UEME_RUNPATH:\\XP-SP3-SHARES\Main_Share\Software\npp.6.0.0.Installer.exe (1)

The Userassist registry key[7] showed that the “corey” user account ran a program called “npp.6.0.0.Installer.exe” at 4/08/12 3:06:21 PM (EDT) from the “Main_Share” network share. 10 seconds later the svchost.exe file was added to the firewalls authorized applications list which was immediately followed by persistence mechanisms being set for the msqgix.com file. I identified the timeframe of interest as 4/08/12 3:06 PM (EDT). Next I needed to see what other activity was occurring on the system so I decided to create a timeline.

System Timeline

System timelines can provide a good deal of context about data found on a system. Timelines can reveal what other activity was occurring on the system around the time when an event (i.e. malware infection) occurred on the system. This other activity can help answer questions with respect to “how did the compromise happen?” This type of question can still be answered even if someone took actions to clean the system and in the process destroyed the best artifacts available. The registry artifacts provided indications that the “corey” user account might have been responsible for the malware infection. As a result, I wanted my timeline to include the Last Write times of every Registry key in the “corey” user account NTUSER.DAT hive to help see what the account was doing and what changes the malware made to the hive. The only other timeline information I wanted initially was the filesystem metadata since it shows activity on the system. My timeline consisting of just filesystem metadata and the “corey” NTUSER.DAT Registry hive metadata showed the following activity occurring around 4/08/2012 3:06 PM (EDT). The table below illustrates some entries from the timeline.

The timeline revealed a great deal of information about the activity on the system around the time the Registry was modified to include references to the malware. Specifically, the “corey” user account accessed a network share named Main_Share on the XP-SP3-Shares computer followed by executing a program named “npp.6.0.0.Installer.exe”.

How the Compromise Occurred

The information I obtained from the host based logs, Windows Registry, and a system timeline was enough to determine how the how the infection occurred.

The “corey” user account launched a program named "npp.6.0.0.Installer.exe" from the Main_Share on the computer XP-SP3-Shares. Within 15 seconds there were multiple indicators in the Registry showing when malware first executed on the system. Those indicators involved three files names (svchost.exe, msqgix.com, and msmhxy.com) that were eventually detected by McAfee antivirus as BackDoor-AMQ (Trojan) prior to being deleted.

The information I obtained from the artifacts left on the system confirmed how I purposely infected the system. I Trojanized a Notepad ++ installer[8] which drops malware when executed[9].


There are some instances when the “CSI” main characters show up to a crime scene that appears to be spotless. There is no victim, blood spatter, knocked over furniture, or anything else to indicate a crime took place. What happened was someone cleaned the crime scene before the characters arrived. When faced with a clean crime scene they do not throw their hands up in the air and say the cleaning prevents them from investigating what happened. Instead they search the scene looking for clues the cleaning might have missed. Areas get sprayed with Fluorescein and then a UV light reveals where blood existed, cracks in objects are checked for blood, or the drains in showers are checked for any evidence. Digital forensics is no different; when a “cleaned” system is encountered then the examination needs to find any information in the artifacts left on a system.

Sometimes there might not be the original malware samples, their metadata, Prefetch files, temporary files, or historical information. It is still incumbent upon us to find any remaining artifacts whether they are host based log files, NTFS artifacts, registry artifacts, or timelines. There are even additional remaining artifacts I didn’t discuss such as ones showing program execution and file access. The Registry contains more information about program execution including the MUICache[10] and the Shim Cache[11] Registry keys. There are artifacts showing what folders and files were accessed by a user account including: Shellbags Registry keys[12], Windows LNK files[13], or Internet Explorer browser history.

The common troubleshooting techniques administrators do when trying to "clean" a system and get it back in working order makes it more challenging for us to perform our analysis. What artifacts the administrators destroy will be different from system to system. However, it’s up to us to find what articles remain and how they can be pieced together to explain what happened.


1. The full path to the registry key is HKLM\Software\ Microsoft\Windows\CurrentVersion\Uninstall

2. McAfee outlines the log file locations in their knowledge base https://kc.mcafee.com/corporate/index?page=content&id=KB51377

3. McAfee write-up for BackDoor-AMQ http://vil.nai.com/vil/content/v_100037.htm

4. Refer to Brian Carrier’s File System Forensic Analysis book for additional information about NTFS and the artifacts available

5. Willi Ballenthin INDXParse script webpage discussing the INDX artifact http://www.williballenthin.com/forensics/indx/index.html

6. Chad Tilbury wrote an excellent article discussing this behavior http://computer-forensics.sans.org/blog/2011/09/20/ntfs-i30-index-attributes-evidence-of-deleted-and-overwritten-files

7. For additional information about the Userassist Registry key see http://forensicartifacts.com/2010/07/userassist/

8. Virustotal scan showed 32/42 antivirus detected as malicious https://www.virustotal.com/file/84824963c0989568674f329e8dd92eb735f27609ef27e6352347288f62bf1d16/analysis/1334516889/

9. The Malwr dynamic analysis http://malwr.com/analysis/0916af77efc95add28e0abdd17b8a64c/

10. Harlan Carvey’s blog post about the MUICache http://windowsir.blogspot.com/2005/12/mystery-of-muicachesolved.html

11. Whitepaper about the forensic significance of the Shim Cache https://blog.mandiant.com/archives/2459

12. Chad Tilbury article about Windows 7 Shellbags http://computer-forensics.sans.org/blog/2011/07/05/shellbags

13. Article "Evidentiary Value of Link Files" http://www.forensicfocus.com/link-file-evidentiary-value

Article Edited By:

Harlan Carvey
Don C. Weber

So You Wanna Be A DFIR Blogger

Tuesday, October 16, 2012 Posted by Corey Harrell 5 comments
It was a little over two years ago when I started Journey Into Incident Response (aka jIIr). In these two years I learned a lot about blogging on technical topics so I wanted to share some tips and advice for those considering taking the plunge into the blogosphere. The following are some things to consider from planning your blog to setting it up to maintaining it:

      -  Why
      -  Motivation
      -  Post Frequency
      -  Content
      -  Publishing Method
      -  Blog Template
      -  Blog Configuration
      -  Blog Post Tips
      -  Advertising
      -  Gauging Interest
      -  Motivation


My first question to any would be blogger is why. Why do you want to put yourself through the agony of sacrificing your personal time and resources so you can share your experiences and research. There are other avenues to take; write an article and submit it to a site offering free content (such as DFI News or Forensic Focus). Write a post for a blog that publishes guest posts (such as SANs Forensic blog or Girl, Unallocated). I’m not trying to talk anyone out of blogging since it has been a rewarding experience. On the contrary, I’m just trying to get my point across that blogging is a lot of work and in the end you are doing it for free. When I decided to start blogging I told my wife “it will be easy”. Sure I had a new born to go along with my two other sons, was pursing my Masters degree, and still had a full time security job but I seriously thought putting together a few posts a month would be a cake walk. My perspective changed pretty quick after I wrote my first few posts.

If you have any hesitation about not wanting to put in the work then consider the other options available. If you made up your mind and blogging is the route you want to take then the remaining tips may be helpful.


People who start blogging have a reason why they are doing it. For some it’s to give back to the community, for others it’s for name recognition, for some it’s a platform they control to share their research, and for the rest it’s any number of reasons. Before you even start setting up a blog make sure you know what your true motivation is. There will be times when you have writers block or you just don’t feel like writing anything so whatever your reason is for blogging needs to be enough to motivate you to put the keyboard to word processor. Your motivation needs to come from within since most of the time others can’t do this for you.


This was something that helped me so I wanted to pass this nugget along. Before you even start worrying about content, site design, or any other details take some time to consider how often you want to update your blog. If you look at other DFIR blogs you will notice a range in how often they are updated. From multiple updates in a week to monthly updates to yearly postings. As an author, I found it helpful to set myself a monthly goal of how many posts I wanted to put together. It helped to not only plan better on how to reach my monthly goal but it helped get me into the habit of writing regularly. As a blog reader, I tend to check the sites with a more regular update schedule more so I assume others readers do the same. If a blog gets updated at random times then it tends to fall off my radar until I see it in my RSS feeds. Whatever goal you set for yourself it’s not something that needs to be publicized. It’s a personal goal for yourself and only for you to know. I’m only mentioning my goal since I’m giving this advice. I always wanted to write three substantial posts per month so at the end of the year I would have 36 decent write-ups.


I also found it helpful to at least pick a theme for the blog. There are times when I’m not sure what to write about so having a theme gives me something to fall back on. As you might have noticed my theme is in the title: Journey Into Incident Response. I wanted to blog about the different things I learn and experience as I work on improving my skills and knowledge to investigate security incidents. If you do decide to pick a theme it doesn’t mean you are locked into it. Write about whatever you want whether if it’s about a book, tool, article, or anything else you are working on in the moment. The theme is just a crutch for when you start to run out of ideas which brings me to my next point. Make sure you have a blog idea hopper. Keep a list of different ideas for future posts and always add to it when you think of something new. Some ideas may never go beyond the hopper while others may turn into great articles. One of the reasons why I don’t struggle with ideas for posts is because I constantly have between 5 to 10 ideas in my hopper. If I need something to write about then I just look over my hopper and pick the one that interests me the most. Case in point, the idea for this post has been in my hopper for months.

Publishing Method

At this point you know why you want to blog, what your motivation is, how often you will update it, and you have a general idea about what content you want. The biggest decision you will now make is how you want to host your blog. The two most frequent publishing applications I see DFIR bloggers use are Word Press and Blogger. If you aren’t sure about what publishing application to use then reach out to the blog authors you read. I bet the authors are more than willing to let you know why they choose what they did and how they feel about their decision. As for me I went with Blogger for two simple reasons. First was because most of the blogs I followed at the time used the service and second was because I didn’t want to have to worry about maintaining software updates. All I want to do is blog and Blogger enabled me to do that.

Blog Template

The second biggest decision will be what template to use for your blog. The template is how your blog looks and what people will stare at when reading your posts. Your publishing application may have a few templates available that meet your needs. If the built-in templates aren’t what you are looking for then there are free templates available online. What sites should you use to get a free template? Great question and it’s still one I can’t really answer today. The last thing I wanted was to get a free template with an embedded malicious link that would attack any visitor of my blog. So I took a closer look at a few DFIR blogs I followed to see where they got their templates. I went to each blog and viewed the site’s source code to find the template’s author website. The screenshot is from my blog’s current template but it’s also the website I saw in a ton of other DFIR blogs.

Blog Configuration

Remember growing up when people said first impressions matter? I think the statement is true even for blogging. When I was in the process of configuring my blog one setting I loved was the ability to restrict access to my blog. I pretty much prevented anyone from seeing the blog while I tried out different templates, options, and layouts. In Blogger I even used the setting preventing the site getting indexed by Google. I only removed the permissions, thus allowing anyone to see the blog, when I had everything set up the way I wanted. Configuring your blog is a matter of preference so my only advice is to don’t unveil it until it’s set up the way you want it.

Blog Post Tips

ITAuditSecurity has some great posts about blogging tips. As it relates to putting a post together one tip I wanted to echo was in his post Blogging: Choose Great Titles and Intro Sentences. His reasoning is not only do they grab the attention of readers but they also help in having better search engine results. I completely agree with his points and I wanted to build on it with another point. Picking good titles and intro sentences helps to let the reader know exactly what the post will be about. If the point of the post can’t be conveyed in a title or one sentence then make sure it is conveyed in the first paragraph. If the content of the post isn’t clear upfront then some readers will stop reading before they reach the part of the post where you make your point. In all of my posts I try very hard to make sure that the reader knows exactly what I’ll be talking about by the time they finish reading the first paragraph.


I remember thinking very clearly when I was getting ready to launch the blog “how do you advertise it to others”. I thought there was some secret so I reached out to Harlan for advice. At the time I was just a name from the Win4n6 group who Harlan helped once before but I figured who else would be better to ask them someone who has been blogging for years. Harlan’s response to my question about the secret to advertising was:

“Add your blog to your email signature, and tell others about it. Pass it around. I, and others, constantly link to blogs and posts that are interesting and informative. There's no real secret”

Here I was thinking there was some secret; some involved advertising process only known to bloggers but in the end advertising has actually been the easy part. Two years later I can honestly say Harlan’s advice was spot on.

Gauging Interest

Don’t get me wrong about my next comment. I truly appreciate all the feedback I have gotten over the last two years. The conversations in person, comments offline, and comments posted to jIIr. When you start blogging treat any feedback you get like gold. Feedback is the best way to get an idea about your blog’s content so cherish it when someone gives it to you. The reason is because the majority of blog readers don’t provide feedback. They don’t leave comments, send emails, or contact you using other means. Thinking about it I fall in the same boat. I follow over 300 blogs and my comment to read ratio is pretty low. For the first year blogging it felt as if I was talking to myself. I would keep posting different content but I didn’t get a lot of feedback. I wasn’t sure what content went over well and which ones as Harlan says “went over like a fart”. In these situations Google Analytics will be your friend. Google Analytics keeps stats about your site such as pageviews for each post and referrals to your blog. For the times when I don’t get feedback I can get a rough idea about the content people like by looking at the page views. However, some of my posts where I got great feedback were the same ones with low pageviews. Leverage Google Analytics as a tool to guage interest on your site but remember it is not fool-proof.


As I mentioned before blogging has been one of the most rewarding things I have done. It has required a lot of sacrifice but it has made me into a better DFIR practitioner. There are times when I felt as if I wasn’t adding value; times when I was flying high because my research and posts has helped others. Regardless of what happens when you blog, the most important advice I can give is to stay true to what motivated you to blog in the first place. If you are working towards accomplishing what you set out to do then the rest doesn’t matter. Enjoy the ride and remember to say thanks to those who give shout outs about your blog or provide feedback.

You Are Not Admin with UAC

Monday, October 8, 2012 Posted by Corey Harrell 1 comments
There is a tendency to focus on what is different when we are faced with newer operating systems. What are the security changes and how does that impact security testing against it? What are the new artifacts and what new information do they provide? The focus is mostly on the changes as it relates to us looking at the operating system. However, there are other changes that may impact us even more and the way we do our jobs. These changes occur when we use these newer operating systems on the workstations we use for analysis and the changes impact how our tools operate. The User Account Control feature in the newer operating systems is one such change impacting how we use our tools.

User Account Control (UAC) was first introduced with Windows Vista and the feature carried over to Windows 7. By default, UAC is turned on in both operating systems. “The primary goal of User Account Control is to reduce the exposure and attack surface of the Windows 7 operating system by requiring that all users run in standard user mode, and by limiting administrator-level access to authorized processes.” This means even if a user account is in the administrators group every application the account runs will only have standard user privileges instead of the all powerful administrative privileges. In essence, we are not administrators when UAC is turned on.

It’s fairly easy to see the impact UAC has on a user account with administrative privileges. With UAC turned on, open a command prompt and type the command “whoami.exe /priv” to see the privileges of the logged on user account (if your system has UnxUtils configured in your path then make sure to run Windows\System32\whoami.exe).

C:\> whoami.exe /priv

As shown above the user account only has five privileges and none of them are the elevated privileges typically associated with administrator accounts. The two ways to get around UAC is to either turn it off or to use the “Run As” feature when starting an application. Continuing to see the impact of UAC, with the same user account re-run the command “whoami.exe/ priv” with either UAC completely turned off or with a command prompt opened with the “Run As” feature. Notice the difference in the privileges the user account has as shown below.

C:\> whoami.exe /priv

UAC Impact on Digital Forensic and Incident Response Tools

UAC will impact any application that requires administrative privileges to function properly. I first encountered the impact UAC has on applications is when I was working on a script to examine volume shadow copies. My script needed elevated privileges to work and without it the script would just fail. Why the sudden interest in UAC now? Last week a new DFIR program was released and the tool requires elevated privileges to run properly. A few people encountered an error when running the program on both Windows Vista and Windows 7. The program in question is Harlan’s Forensic Scanner and the error some people saw when clicking the Init button is below.

The error is a direct result of UAC being enabled on the workstations running the Forensic Scanner. To get around UAC and thus the error, all one has to do is use the “Run As” feature when launching the Forensic Scanner (or in my case by disabling UAC completely). Again, the UAC error is not unique to the Forensic Scanner; it’s any program that requires administrative privileges. With that said let’s take a closer look at what is really occurring with the scanner and UAC.

I monitored the Forensic Scanner as it executed with ProcessMonitor using an administrative user account with UAC turned on. The screenshot below shows the first permission issue encountered due to the restricted privileges imposed by UAC.

The event shows access is being denied when the scanner tries to open the M:\Windows\system32\config\software hive in my mounted forensic image. Now let’s take a look at the same event with UAC turned off (or with the scanner being executed with the “Run As” feature).

The event shows the result is now a success instead of the denied access previously encountered. The end result is the software registry hive was opened. Now the error some people are encountering makes a little more sense: “No filename specified at PERL2EXE_STORAGE/WinSetup.pm line 136”. The Forensic Scanner is unable to open the registry hives because the user account being used has standard privileges since UAC removed the administrative privileges.

When we upgrade our workstations to newer operating systems it may impact the way our tools work. The User Account Control feature introduced with Windows Vista and carried over to Windows 7 is just one example. When the User Account Control feature is turned on any tools needing administrative privileges will no longer function properly.
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