Backdoor.Win32.ANDROM.DYSGXE

February 05, 2022
 Analysis by: Khristian Joseph Morales
 ALIASES:

Worm:Win32/Gamarue.AR (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

92,052,352 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Dec 2021

Arrival Details

This Backdoor 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 Backdoor drops the following files:

  • %ProgramData%\ms{random}.exe

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

It adds the following processes:

  • msiexec.exe

It injects codes into the following process(es):

  • msiexec.exe

Autostart Technique

This Backdoor modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
{random number} = %ProgramData%\ms{random}.exe → If run as Administrator

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = %ProgramData%\ms{random}.exe

Other System Modifications

This Backdoor modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Download exe
  • Update plug-in
  • Delete bot
  • Install plug-in

It connects to the following websites to send and receive information:

  • http://{BLOCKED}derstatus.ru/order.php
  • http://{BLOCKED}rentia.ru/diff.php
  • http://{BLOCKED}0s7he.ru

It posts the following information to its command and control (C&C) server:

  • OS Version
  • VolumeSerialNumber
  • Local IP Address
  • Botnet ID
  • Administrator rights of current malware process

Other Details

This Backdoor connects to the following URL(s) to check for an Internet connection:

  • yahoo.com
  • google.com
  • bing.com
  • microsoft.com
  • update.microsoft.com

It does the following:

  • Checks if the following processes related to virtual environment, emulation software, and network monitoring software are running in the affected machine. If so, it will perform infinite sleep.
    • vmwareuser.exe
    • vmwareservice.exe
    • vboxservice.exe
    • vboxtray.exe
    • sandboxiedcomlaunch.exe
    • sandboxierpcss.exe
    • procmon.exe
    • regmon.exe
    • filemon.exe
    • wireshark.exe
    • netmon.exe
    • prl_tools_service.exe
    • prl_tools.exe
    • prl_cc.exe
    • sharedintapp.exe
    • vmtoolsd.exe
    • vmsrvc.exe
    • vmusrvc.exe
    • python.exe
    • perl.exe
    • avpui.exe
  • It will not proceed with its routine if the system's language is any of the following:
    • Russian
    • Ukrainian
    • Belarusian
    • Kazakh
  • Connects to the following Network Time Protocol (NTP) servers:
    • africa.pool.ntp.org
    • oceania.pool.ntp.org
    • asia.pool.ntp.org
    • south-america.pool.ntp.org
    • north-america.pool.ntp.org
    • europe.pool.ntp.org
    • pool.ntp.org

It deletes the initially executed copy of itself.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.360.05

FIRST VSAPI PATTERN DATE:

04 Feb 2022

VSAPI OPR PATTERN File:

17.361.00

VSAPI OPR PATTERN Date:

05 Feb 2022

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.XXPE50FFF053

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

Restore this modified 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\Explorer\Advanced
    • ShowSuperHidden = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • Hidden = 2

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
    • {random number} = %ProgramData%\ms{random}.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    • Load = %ProgramData%\ms{random}.exe

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.
  • %ProgramData%\ms{random}.exe

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.ANDROM.DYSGXE. 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.

Step 9

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.ANDROM.DYSGXE. 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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