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VBS_SOYSOS.A
Malware type: Worm
Destructive: No
Platform: Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Encrypted: Yes
In the wild: Yes

Overview


Infection Channel: Propagates via removable drives, Downloaded from the Internet, Dropped by other malware

This worm arrives via removable drives. It may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

Technical Details


File size: 2,045 bytes
File type: VBS
Memory resident: Yes
Initial samples received date: 11 Sep 2013
Payload: Terminates processes

Arrival Details

This worm arrives via removable drives.

It may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This worm drops the following copies of itself into the affected system:

  • %User Temp%\D&D.vbe

(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, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Autostart Technique

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

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SoyUnVirus(Denia&Dania) = "%User Temp%\D&D.vbe"

Other System Modifications

This worm deletes the following files:

  • {Removable Drive Letter}:\{path and file name}.mp3
  • {Removable Drive Letter}:\{path and file name}.dwg
  • {Removable Drive Letter}:\{path and file name}.jpg

It adds the following registry keys:

HKEY_CURRENT_USER\software\DD 2.0

Propagation

This worm drops copies of itself in the following drives:

  • {Removable Drive Letter}:\{path and file name}.jpg.vbe
  • {Removable Drive Letter}:\{path and file name}.dwg.vbe
  • {Removable Drive Letter}:\{path and file name}.mp3.vbe

Process Termination

This worm terminates the following processes if found running in the affected system's memory:

  • taskmgr.exe
  • regedit.exe

NOTES:

Where {path and file name} is the name and full path of files with extension *.dwg, *.jpg and *.mp3 found in removable drives

Solution


Minimum scan engine: 9.300
First VSAPI Pattern File: 10.272.04
First VSAPI Pattern Release Date: 11 Sep 2013
VSAPI OPR Pattern Version: 10.273.00
VSAPI OPR Pattern Release Date: 12 Sep 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn more ]

Step 3

Delete this registry key

[ 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
    • DD 2.0

Step 4

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_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • SoyUnVirus(Denia&Dania) = "%User Temp%\D&D.vbe"

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as VBS_SOYSOS.A. 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 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • {Removable Drive Letter}:\{path and file name}.mp3
  • {Removable Drive Letter}:\{path and file name}.dwg
  • {Removable Drive Letter}:\{path and file name}.jpg


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Analysis By: Mark Joseph Manahan

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