Backdoor.VBS.XWORM.A

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.

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

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%\{8 Random Characters}.{3 Random Characters}.ps1
• %User Temp%\{8 Random Characters}.{3 Random Characters}.psm1

(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 uses Windows Management Instrumentation (WMI) to execute malicious code:

• powershell -NoProfile -WindowStyle Hidden -Command "[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String('{Base64 Encoded Command}')) | Invoke-Expression"

Other System Modifications

This Backdoor deletes the following files:

• %User Temp%\{8 Random Characters}.{3 Random Characters}.ps1
• %User Temp%\{8 Random Characters}.{3 Random Characters}.psm1

(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).)

Other Details

This Backdoor connects to the following possibly malicious URL:

• http://dn721801.ca.{BLOCKED}e.org
• https://{BLOCKED}e.org/download/optimized_msi_20250904/optimized_MSI.png

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