Analysis by: Lorenzo Martin Lopez
ALIASES:

Backdoor.Win32.Wabot.a (KASPERSKY), Backdoor:Win32/Wabot.A (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

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: 111,107 bytes
File Type: EXE
Initial Samples Received Date: 23 Oct 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 a copy of itself in the following folders using different file names:

  • %System%\xdccPrograms
  • %System%\DC++ Share

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

It drops the following file(s)/component(s):

  • %AppDataLocal%\VirtualStore\marijuana.txt
  • %System Root%\rar.bat
  • %System Root%\marijuana.txt
  • %System%\xdccPrograms\{Name of Random file in System}.exe
  • %System%\DC++ Share\{Name of Random file in System}.exe
  • %System%\xdccPrograms\{Name of Random file in System}.rar
  • %System%\DC++ Share\{Name of Random file in System}.rar

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It adds the following processes:

  • cmd /c %System Root%\rar.bat
  • %Program Files%\WinRAR\WinRAR.exe a -idp -inul -c- -m5 "%System%\xdccPrograms\{Name of Random file in System}" "%System%\xdccPrograms\{Name of Random file in System}.exe"
  • %Program Files%\WinRAR\WinRAR.exe a -idp -inul -c- -m5 "%System%\DC++ Share\{Name of Random file in System}" "%System%\DC++ Share\{Name of Random file in System}.exe"

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
shell = Explorer.exe sIRC4.exe

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.492.03
FIRST VSAPI PATTERN DATE: 22 Jan 2021
VSAPI OPR PATTERN File: 16.493.00
VSAPI OPR PATTERN Date: 23 Jan 2021

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

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 NT\CurrentVersion\Winlogon
    • shell = Explorer.exe sIRC4.exe

Step 4

Identify and delete files detected as Trojan.Win32.WABOT.DISC using the Recovery Console

[ Learn More ]

Step 5

Search and delete this folder

[ 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.
  • %System%\xdccPrograms
  • %System%\DC++ Share

Step 6

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win32.WABOT.DISC. 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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