In this post, we covered investigating a compromised Windows machine with WMI Backdoors. This was part of TryHackMe Investigating Windows 2.0 lab.

Investigating windows machines is part of the incident response process. In this tutorial, we conducted live forensic on the machine which is typically done after you perform a bit by bit copy of the disk and RAM since compromised machines are not reliable for forensic investigation and the output of every command can be altered by the malware or rootkit.

The machine we are investigating is infected with WMI (Windows Management Instrumentation ) backdoor. WMI Backdoors rely on event filters and event consumers. Event filters are the conditions that if met event consumers get executed which normally are specific actions performed on windows.

Obtenir les notes du certificat OSCP

An example of WMI Backdoor is ici

Download the brief material of this post as PDF

Task Answers

What registry key contains the same command that is executed within a scheduled task?
HKCU\Environment\UserIntMprLogonScript
What analysis tool will immediately close if/when you attempt to launch it?

procexp64.exe
What is the full WQL Query associated with this script?

SELECT * FROM Win32_ProcessStartTrace WHERE ProcessName = ‘procexp64.exe’
What is the script language?

VBScript
What is the name of the other script?

LaunchBeaconingBackdoor
What is the name of the software company visible within the script?

Motobit Software
What 2 websites are associated with this software company? (answer, answer)

http://www.motobit.com, http://motobit.cz
Search online for the name of the script from Q5 and one of the websites from the previous answer. What attack script comes up in your search?

WMIBackdoor.ps1
What is the location of this file within the local machine?

C:\TMP
Which 2 processes open and close very quickly every few minutes? (answer, answer)
mim.exe, powershell.exe
What is the parent process for these 2 processes?

svchost.exe
What is the first operation for the first of the 2 processes?

Process Start
Inspect the properties for the 1st occurrence of this process. In the Event tab what are the 4 pieces of information displayed? (answer, answer, answer, answer)

Parent PID, Command line, Current directory, Environment
Inspect the disk operations, what is the name of the unusual process?

No process
Run Loki. Inspect the output. What is the name of the module after Init?

WMIScan
Regarding the 2nd warning, what is the name of the eventFilter?
ProcessStartTrigger
For the 4th warning, what is the class name?

__FilterToConsumerBinding
What binary alert has the following 4d5a90000300000004000000ffff0000b8000000 as FIRST_BYTES?

nbtscan.exe
According to the results, what is the description listed for reason 1?
Known Bad / Dual use classics
Which binary alert is marked as APT Cloaked?

p.exe
What are the matches? (str1, str2)

psexesvc.exe, Sysinternals PsExec
Which binary alert is associated with somethingwindows.dmp found in C:\TMP?

schtasks-backdoor.ps1
Which binary is encrypted that is similar to a trojan?

xCmd.exe
There is a binary that can masquerade itself as a legitimate core Windows process/image. What is the full path of this binary?

C:\Users\Public\svchost.exe
What is the full path location for the legitimate version?

C:\Windows\System32
What is the description listed for reason 1?

Stuff running where it normally shouldn’t
There is a file in the same folder location that is labeled as a hacktool. What is the name of the file?

en-US.js
What is the name of the Yara Rule MATCH?

CACTUSTORCH
Which binary didn’t show in the Loki results?

mim.exe
Complete the yar rule file located within the Tools folder on the Desktop. What are 3 strings to complete the rule in order to detect the binary Loki didn’t hit on? (answer, answer, answer)

mk.ps1, mk.exe, v2.0.50727

Video Walk-Through