Analysis by: Raymart Christian Yambot

ALIASES:

Trojan:Win32/Leonem (MICROSOFT)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Type: , EXE
Memory Resident: No
Initial Samples Received Date: 26 Sep 2024
Payload: Connects to URLs/IPs, Drops files

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following files:

  • %User Temp%\nsbB44D.tmp
  • %User Temp%\Underdimensioneringer\Afbringernes212.Afl
  • %User Temp%\Underdimensioneringer\silviculturist.Lan
  • %User Temp%\Underdimensioneringer\parters.vis
  • %User Temp%\Underdimensioneringer\pulmonary.tol
  • %User Temp%\Underdimensioneringer\smilingness.bol
  • %User Profile%\Pictures\udtydningens.ini
  • %User Temp%\{Random 8 characters}.{Random 3 characters}.ps1 → Deleted Afterward
  • %User Temp%\{Random 8 characters}.{Random 3 characters}.psm1 → Deleted Afterward
  • %User Temp%\Underdimensioneringer\{Malware Name}.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • "powershell.exe" -windowstyle hidden "$Smaltz=Get-Content '%User Temp%\Underdimensioneringer\silviculturist.Lan';$Kvindeligt=$Smaltz.SubString(51654,3);.$Kvindeligt($Smaltz)
  • %Program Files%\windows mail\wab.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap
UNCAsIntranet = 0

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap
AutoDetect = 1

(Note: The default value data of the said registry entry is 0.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.{BLOCKED}.19/UNjIjisrUii216.bin

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.616.05
FIRST VSAPI PATTERN DATE: 27 Sep 2024
VSAPI OPR PATTERN File: 19.617.00
VSAPI OPR PATTERN Date: 28 Sep 2024

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

    • TROJ.Win32.TRX.XXPE50FSX051

Step 2

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 3

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap
  • UNCAsIntranet = 0
  • UNCAsIntranet = 1
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap
  • AutoDetect = 1
  • AutoDetect = 0

Step 5

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\nsbB44D.tmp
  • %User Temp%\Underdimensioneringer\Afbringernes212.Afl
  • %User Temp%\Underdimensioneringer\silviculturist.Lan
  • %User Temp%\Underdimensioneringer\parters.vis
  • %User Temp%\Underdimensioneringer\pulmonary.tol
  • %User Temp%\Underdimensioneringer\smilingness.bol
  • %User Profile%\Pictures\udtydningens.ini
  • %User Temp%\{Random 8 characters}.{Random 3 characters}.ps1
  • %User Temp%\{Random 8 characters}.{Random 3 characters}.psm1
  • %User Temp%\Underdimensioneringer\{Malware Name}.exe

Step 6

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win32.LEONEM.B. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:


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