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VBS_AGENT.AVKG
Malware type: Worm
Destructive: No
Platform: Windows 2000, XP, Server 2003
Encrypted: No
In the wild: Yes

Technical Details


File size: 11,330 bytes
File type: Script
Memory resident: No
Initial samples received date: 06 May 2010

Installation

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

  • %User Profile%\My Documents\df5srvc.bfe
  • %System Root%\{all folders found}\desktop.ini
  • %System Root%\desktop.ini

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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
Df5serv = Wscript.exe //e:VBScript "%User Profile%\My Documents\df5srvc.bfe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Explorer = Wscript.exe //e:VBScript "%Application Data%\Microsoft\CD Burning\dekstop.ini"

Other System Modifications

This worm adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\SuperHidden

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System

It adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\SuperHidden
WarningIfNotDefault = fandy love yuyun

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistrytools = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = http://www.{BLOCKED}t.co.nr

(Note: The default value data of the said registry entry is {default homepage}.)

It modifies the following registry entries to hide files with Hidden attributes:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\SuperHidden
UncheckedValue = 1

(Note: The default value data of the said registry entry is 0.)

Propagation

The said .INF file contains the following strings:

[autorun]
open=WScript.exe //e:VBScript dekstop.ini auto
shell\open=Open
shell\open\Command=WScript.exe //e:VBScript dekstop.ini auto
shell\open\Default=1
shell\explore=Explore
shell\explore\Command=WScript.exe //e:VBScript dekstop.ini auto

Dropping Routine

This worm drops the following files:

  • %System Root%\autorun.inf - detected by Trend Micro as Mal_Otorun1
  • %System Root%\{all folders found}\autorun.inf - detected by Trend Micro as Mal_Otorun1
  • %System Root%\Microsoft.lnk
  • %System Root%\Aplikasi.lnk
  • %System Root%\{all folders found}\Microsoft.lnk
  • %System Root%\{all folders found}\Aplikasi.lnk
  • %System%\Serv60d.dll - nonmalicious
  • %System%\auto.exe - detected by Trend Micro as Mal_Otorun1
  • %System%\v.doc - nonmalicious

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Details

This worm does the following:

  • It creates shortcut links of all folders found in the %System Root% folder.

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Solution


Minimum scan engine: 8.900
VSAPI Pattern File: 7.150.07
VSAPI Pattern Release Date: 06 May 2010

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

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
    • Df5serv = Wscript.exe //e:VBScript %User Profile%\My Documents\df5srvc.bfe

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Explorer = Wscript.exe //e:VBScript %Application Data%\Microsoft\CD Burning\dekstop.ini

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\Microsoft\Windows\CurrentVersion\Explorer\Advanced\
    • Folder
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\
    • System

Step 4

Restore this modified 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\Internet Explorer\Main
    • From: Start Page = http://www.{BLOCKED}t.co.nr
    • To: Start Page = about:blank
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\SuperHidden
    • From: UncheckedValue = 0<
    • To: UncheckedValue = 1

Step 5

Search and delete this file

[ Learn more ]
There may be some component 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.
  • %System Root%\{all folders found}\Aplikasi.lnk
  • %System Root%\{all folders found}\autorun.inf - detected by Trend Micro as Mal_Otorun1
  • %System Root%\{all folders found}\Microsoft.lnk
  • %System Root%\Aplikasi.lnk
  • %System Root%\autorun.inf - detected by Trend Micro as Mal_Otorun1
  • %System Root%\Microsoft.lnk
  • %System%\auto.exe - detected by Trend Micro as Mal_Otorun1
  • %System%\Serv60d.dll - nonmalicious
  • %System%\v.doc - nonmalicious

Step 6

Search and delete AUTORUN.INF files created by VBS_AGENT.AVKG that contain these strings

[ Learn more ]

Step 7

Scan your computer with your Trend Micro product to delete files detected as VBS_AGENT.AVKG. 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.


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Analysis By: Sabrina Lei Sioting

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