arrow_back
search
close

Trojan.MSIL.NEGASTEAL.DYSHRSKZ

January 23, 2024
 Modified by: Raighen Sanchez
 ALIASES:

Trojan:MSIL/AgentTesla.KABR!MTB (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • 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. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

936,960 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Jan 2024

Payload:

Drops files, Connects to URLs/IPs, Modifies system registry

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.

However, as of this writing, the said sites are inaccessible.

Installation

This Trojan drops the following files:

  • %User Temp%\tmp{4 random alphanumeric characters}.tmp → Deleted afterward
  • %User Temp%\{8 random alphanumeric characters}.{3 random alphanumeric characters}.ps1 → Deleted afterward
  • %User Temp%\{8 random alphanumeric characters}.{3 random alphanumeric characters}.psm1 → Deleted afterward
  • %User Temp%\{8 random alphanumeric characters}.{3 random alphanumeric characters}.ps1 → Deleted afterward
  • %User Temp%\{8 random alphanumeric characters}.{3 random alphanumeric characters}.psm1 → Deleted afterward

(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).)

It drops the following copies of itself into the affected system:

  • %Application Data%\VrkLILo.exe
  • %Application Data%\FdnCz\FdnCz.exe

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

It adds the following processes:

  • "%System%\WindowsPowerShell\v1.0\powershell.exe" Add-MpPreference -ExclusionPath "%User Temp%\{Malware filename}.exe"
  • "%System%\WindowsPowerShell\v1.0\powershell.exe" Add-MpPreference -ExclusionPath "%Application Data%\VrkLILo.exe"
  • schtasks.exe /Create /TN "Updates\VrkLILo" /XML "%User Temp%\tmp{4 random alphanumeric characters}.tmp"

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

It creates the following folders:

  • %Application Data%\FdnCz

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

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • rWIUlkpYvpVhU

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
FdnCz = %Application Data%\FdnCz\FdnCz.exe

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

  • https://{BLOCKED}.{BLOCKED}.{BLOCKED}.211

Other Details

This Trojan connects to the following URL(s) to get the affected system's IP address:

  • {BLOCKED}fy.org

It adds the following scheduled tasks:

  • Location: %System%\Tasks\Updates\VrkLILo
    Name: VrkLILo
    Trigger: At tasks creation/modification and At log on
    Action: Start a program - %Application Data%\VrkLILo.exe

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

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.930.03

FIRST VSAPI PATTERN DATE:

09 Jan 2024

VSAPI OPR PATTERN File:

18.931.00

VSAPI OPR PATTERN Date:

10 Jan 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.XXPE50FFF077

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

Restart in Safe Mode

[ Learn More ]

Step 5

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • FdnCz - %Application Data%\FdnCz\FdnCz.exe

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each {Task Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. If the strings match the list above, delete the task.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

Step 6

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\
    • FdnCz = %Application Data%\FdnCz\FdnCz.exe

Step 7

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Application Data%\FdnCz

Step 8

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.
  • %Application Data%\VrkLILo.exe
  • %Application Data%\FdnCz\FdnCz.exe
  • %User Temp%\tmp{4 random alphanumeric characters}.tmp
  • %User Temp%\{8 random alphanumeric characters}.{3 random alphanumeric characters}.ps1
  • %User Temp%\{8 random alphanumeric characters}.{3 random alphanumeric characters}.psm1
  • %User Temp%\{8 random alphanumeric characters}.{3 random alphanumeric characters}.ps1
  • %User Temp%\{8 random alphanumeric characters}.{3 random alphanumeric characters}.psm1

Step 9

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.MSIL.NEGASTEAL.DYSHRSKZ. 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 this Knowledge Base page for more information.


Did this description help? Tell us how we did.