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VBS_AUTORUN.ACE

October 09, 2012
 Analysis by: MarfelTi
 ALIASES:

VBS.Invadesys.A (Symantec); Worm:VBS/Invadesys.F (MIcrosoft); Worm.VBS.Autorun.kh (Kaspersky); VBS/Autorun.worm.k (McAfee)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


This worm arrives by connecting affected removable drives to a system. It arrives by accessing affected shared networks.

It drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names. It drops copies of itself in all drives. These dropped copies use the names of the folders located on the said drives for their file names. It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size:

24,577 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

27 Jun 2011

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It arrives by accessing affected shared networks.

Installation

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

  • %drive%\{random numbers}.vbs

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{20D04FE0-3AEA-1069-A2D8-08002B30309D}\shell\
explore\command
@ = "%SystemRoot%\System32\WScript.exe "%WINDOWS%\explorer.exe:{random numbers}.vbs" EMC"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{20D04FE0-3AEA-1069-A2D8-08002B30309D}\shell\
open\command
@ = "%SystemRoot%\System32\WScript.exe "%WINDOWS%\explorer.exe:{random numbers}.vbs" EMC"

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = "%SystemRoot%\system\svchost.exe "%WINDOWS%\system32\smss.exe:{random numbers}.vbs""

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

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Applications\iexplore.exe\shell\
open\command
@ = "%SystemRoot%\System32\WScript.exe "%WINDOWS%\explorer.exe:{random numbers}.vbs" OIE"

(Note: The default value data of the said registry entry is "%Program Files%\Internet Explorer\iexplore.exe" %1 .)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
batfile\shell\open\
command
@ = "%SystemRoot%\System32\WScript.exe ""%WINDOWS%\explorer.exe:{random numbers}.vbs" %1 %*""

(Note: The default value data of the said registry entry is "%1" %* .)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
chm.file\shell\open\
command
@ = "%SystemRoot%\System32\WScript.exe ""%WINDOWS%\explorer.exe:{random numbers}.vbs" %1 %*""

(Note: The default value data of the said registry entry is "%WINDOWS%\hh.exe" %1 .)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
cmdfile\shell\open\
command
@ = "%SystemRoot%\System32\WScript.exe ""%WINDOWS%\explorer.exe:{random numbers}.vbs" %1 %*""

(Note: The default value data of the said registry entry is "%1" %* .)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
hlpfile\shell\open\
command
@ = "%SystemRoot%\System32\WScript.exe ""%WINDOWS%\explorer.exe:{random numbers}.vbs" %1 %*""

(Note: The default value data of the said registry entry is %SystemRoot%\System32\winhlp32.exe %1 .)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
inffile\shell\open\
command
@ = "%SystemRoot%\System32\WScript.exe ""%WINDOWS%\explorer.exe:{random numbers}.vbs" %1 %*""

(Note: The default value data of the said registry entry is %SystemRoot%\System32\NOTEPAD.EXE %1 .)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
inifile\shell\open\
command
@ = "%SystemRoot%\System32\WScript.exe ""%WINDOWS%\explorer.exe:{random numbers}.vbs" %1 %*""

(Note: The default value data of the said registry entry is %SystemRoot%\System32\NOTEPAD.EXE %1 .)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
regfile\shell\open\
command
@ = "%SystemRoot%\System32\WScript.exe ""%WINDOWS%\explorer.exe:{random numbers}.vbs" %1 %*""

(Note: The default value data of the said registry entry is regedit.exe "%1" .)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{20D04FE0-3AEA-1069-A2D8-08002B30309D}\shell
@ = ""

(Note: The default value data of the said registry entry is none.)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{871C5380-42A0-1069-A2EA-08002B30309D}\shell\
OpenHomePage\Command
@ = "%SystemRoot%\System32\WScript.exe "C:\WINDOWS\explorer.exe:1330456861.vbs" OIE"

(Note: The default value data of the said registry entry is %Program Files%\Internet Explorer\iexplore.exe .)

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
NOHIDDEN
CheckedValue = "3"

(Note: The default value data of the said registry entry is 2.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = "2"

(Note: The default value data of the said registry entry is 1.)

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • {random numbers}.vbs

It drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.

It drops copies of itself in all drives. These dropped copies use the names of the folders located on the said drives for their file names.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[AutoRun]
Shellexecute=WScript.exe {random numbers}.vbs "AutoRun"
shell\open={random characters}
shell\open\command=WScript.exe {random numbers}.vbs "AutoRun"
shell\open\Default=1
shell\explore={random characters}
shell\explore\command=WScript.exe {random numbers}.vbs "AutoRun"

Dropping Routine

This worm sets the attributes of its dropped file(s) to the following:

  • Hidden
  • System Only

NOTES:

Dropping Routine

This worm sets the attributes of its dropped file(s) to the following:

  • Hidden
  • System Only

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.252.07

FIRST VSAPI PATTERN DATE:

27 Jun 2011

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

Identify and terminate files detected as VBS_AUTORUN.ACE

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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\Windows NT\CurrentVersion\Windows
    • From: load = ”%SystemRoot%\system\svchost.exe %WINDOWS%\system32\smss.exe:{random numbers}.vbs"
      To: ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Applications\iexplore.exe\shell\open\command
    • From: @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs OIE"
      To: "%Program Files%\Internet Explorer\iexplore.exe %1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\batfile\shell\open\command
    • From: @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs %1 %*"
      To: "%1 %*"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\chm.file\shell\open\command
    • From: @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs %1 %*"
      To: "%WINDOWS%\hh.exe %1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\cmdfile\shell\open\command
    • From: @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs %1 %*"
      To: "%1 %*"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\hlpfile\shell\open\command
    • From: @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs %1 %*"
      To: "%SystemRoot%\System32\winhlp32.exe %1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\inffile\shell\open\command
    • From: @  = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs %1 %*"
      To: "%SystemRoot%\System32\NOTEPAD.EXE %1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\inifile\shell\open\command
    • From: @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs %1 %*"
      To: "%SystemRoot%\System32\NOTEPAD.EXE %1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\regfile\shell\open\command
    • From: @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs %1 %*"
      To: "regedit.exe %1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{20D04FE0-3AEA-1069-A2D8-08002B30309D}\shell
    • From: @ = ""
      To: "none"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{871C5380-42A0-1069-A2EA-08002B30309D}\shell\OpenHomePage\Command
    • From: @ = "%SystemRoot%\System32\WScript.exe C:\WINDOWS\explorer.exe:1330456861.vbs OIE"
      To: "%Program Files%\Internet Explorer\iexplore.exe"

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_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{20D04FE0-3AEA-1069-A2D8-08002B30309D}\shell\explore\command
    • @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs EMC"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{20D04FE0-3AEA-1069-A2D8-08002B30309D}\shell\open\command
    • @ = "%SystemRoot%\System32\WScript.exe %WINDOWS%\explorer.exe:{random numbers}.vbs EMC"

Step 5

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\NOHIDDEN
    • From: CheckedValue = "3"
      To: "2"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue = "2"
      To: "1"

Step 6

Search and delete AUTORUN.INF files created by VBS_AUTORUN.ACE that contain these strings

[ Learn More ]


[AutoRun]
Shellexecute=WScript.exe {random numbers}.vbs AutoRun
shell\open={random characters}
shell\open\command=WScript.exe {random numbers}.vbs AutoRun
shell\open\Default=1
shell\explore={random characters}
shell\explore\command=WScript.exe {random numbers}.vbs AutoRun

Step 7

Scan your computer with your Trend Micro product to delete files detected as VBS_AUTORUN.ACE. 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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