Modified By:: Bren Matthew Ebriega

 

Trojan.Win32.Scar.sydj (KASPERSKY)

 PLATFORM:

Windows

 OVER ALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE
Low
Medium
High
Critical

  • Threat Type:
    Backdoor

  • Destructiveness:
    No

  • Encrypted:
    No

  • In the wild:
    Yes

  OVERVIEW

INFECTION CHANNEL: Dropped by other malware, Downloaded from the Internet

Cybercriminals take advantage of the popularity of the Zoom messaging app. This backdoor is found in a fake Zoom installer. This is probably hosted on malicious or suspicious sites.

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.

  TECHNICAL DETAILS

File size: 14424628 bytes
File type: EXE
Memory resident: No
INITIAL SAMPLES RECEIVED DATE: 11 May 2020
PAYLOAD: Drops files, Connects to URLs/IPs, Steals information

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:

  • %User Temp%\pyclient.cmd → Detected as Backdoor.BAT.DEVILSHADOW.THEAABO
  • %User Temp%\cmd_shell.exe → Detected as Trojan.Win32.DEVILSHADOW.THEAABO
  • %User Profile%\boot-startup.vbs → Detected as Trojan.BAT.DEVILSHADOW.THEAABO
  • %User Profile%\new_script.txt → Detected as Trojan.JS.DEVILSHADOW.THEAABO
  • %User Profile%\shell.bat → Detected as Trojan.BAT.DEVILSHADOW.THEAABO
  • %User Temp%\zoom.exe → Legitimate Zoom Installer
  • %User Profile%\node.exe → Legitimate node.exe
  • %System Root%\botnet\client_id_file → contains generated_id
  • %System Root%\botnet\bot_id_{Generated ID} {Hostname} {IP Address} {Client} → Client Identifier
  • %System Root%\botnet\botnet_start.vbs
  • %System Root%\botnet\wget.js
  • %System Root%\botnet\pyclient.cmd → Copy of the one in %User Temp%
  • %System Root%\botnet\scexec-win32.exe
  • %System Root%\botnet\scexec-win64.exe
  • %System Root%\botnet\Rar.exe
  • %System Root%\botnet\K7firewall.exe
  • %System Root%\botnet\unzip.exe
  • %System Root%\botnet\webcam.exe
  • %System Root%\botnet\execute.vbs
  • %User Temp%\av → contains result of Anti-Virus Query

It adds the following processes:

  • %System%\cmd.exe /c %User Temp%\pyclient.cmd
  • %System%\cmd.exe /c %User Temp%\cmd_shell.exe
  • %System%\cmd.exe /c %User Temp%\zoom.exe
  • %System%\cmd.exe /c cd %userprofile% & attrib +s +h +a *.vbs & attrib +s +h +a *.bat & reg add Hkey_CURRENT_USER\software\microsoft\windows\currentversion\run /v bootstartup /t reg_sz /d %userprofile%\boot-startup.vbs /f & shell.bat
  • %System%\cmd.exe /c "Tasklist /FI WINDOWTITLE eq D3ViL ShaDow"
  • %System%\cmd.exe /c "Tasklist /FI WINDOWTITLE eq Administrator: D3ViL ShaDow"
  • %System%\cmd.exe attrib +s +h +a %System Root%\botnet
  • %System%\cmd.exe copy /y %User Temp%\pyclient.cmd %System Root%\botnet\pyclient.cmd
  • %System%\cmd.exe reg add hkcu\software\microsoft\windows\currentversion\run /v botnet /t reg_sz /d C:\botnet\botnet_start.vbs /f
  • %System%\cmd.exe ping www.google.com -n 1
  • %System&\cmd.exe unzip.exe -ox python_client.zip
  • %System%\cmd.exe %System%\WScript.exe %System Root%\botnet\botnet_start.vbs
  • %System%\cmd.exe copy /y %System%\cmd.exe %Public%\explorer.exe
  • %System%\cmd.exe %User Profile%\node.exe new_script.txt
  • %Public%\explorer.exe
  • %System&\cmd.exe wmic /namespace:\root\securitycemter2 path antivirusproduct GET displayName, productState, pathToSignedProductExe

It creates the following folders:

  • %System Root%\botnet

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

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
bootstartup = %User Profile%\boot-startup.vbs

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
botnet = %System Root%\botnet\botnet_start.vbs

Backdoor Routine

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

  • Update/Reset/Terminate Client (Self)
  • Load Client Modules (Self)
  • Log Keystrokes
  • Take Screenshots
  • Record Desktop
  • Operate Webcam
  • Operate CMD
  • Install Programming Languages
  • Download/Upload/Execute Files
  • Install and Operate Ngrok
  • Install and Operate WinVNC
  • List and Modify AutoStart Registries
  • List, Add and Start Scheduled Tasks
  • Check and Elevate User Privileges
  • Execute Shellcode and Scripts
  • Harvest the Following Information:
    • Process List
    • Drive List
    • Directories and Files List
    • System Info
    • Startup Items
    • AntiVirus Info
    • Locally Stored Credentials

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

  • https://hosting303.{BLOCKED}hostapp.com
  • madleets.{BLOCKED}s.net:4444

Download Routine

This Backdoor accesses the following websites to download files:

  • https://raw.{BLOCKED}usercontent.com/DevilBot000/Tools/master/unzip.exe → %System Root%\botnet\unzip.exe
  • https://raw.{BLOCKED}usercontent.com/DevilBot000/Tools/master/python_client.zip → %System Root%\botnet\python_client.zip

  SOLUTION

Minimum scan engine: 9.850
First VSAPI Pattern File: 15.862.04
First VSAPI Pattern Release Date: 11 May 2020
VSAPI OPR PATTERN-VERSION: 15.863.00
VSAPI OPR PATTERN DATE: 12 May 2020

Step 1

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 2

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 3

Identify and terminate files detected as Backdoor.Win32.DEVILSHADOW.THEAABO

[ learnMore ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Delete this registry value

[ learnMore ]

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
    • bootstartup = %User Profile%\boot-startup.vbs
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • botnet = %System Root%\botnet\botnet_start.vbs

Step 5

Search and delete these folders

[ learnMore ]
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.
  • %System Root%\botnet

Step 6

Search and delete this file

[ learnMore ]
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 Profile%\node.exe
  • %System Root%\botnet\client_id_file
  • %System Root%\botnet\bot_id_{Generated ID} {Hostname} {IP Address} {Client}%System Root%\botnet\botnet_start.vbs
  • %System Root%\botnet\wget.js
  • %System Root%\botnet\pyclient.cmd
  • %System Root%\botnet\scexec-win32.exe
  • %System Root%\botnet\scexec-win64.exe
  • %System Root%\botnet\Rar.exe
  • %System Root%\botnet\K7firewall.exe
  • %System Root%\botnet\unzip.exe
  • %System Root%\botnet\webcam.exe
  • %System Root%\botnet\execute.vbs

Step 7

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.DEVILSHADOW.THEAABO. 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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