VBS_AUTORUN.JM

October 08, 2012
 Analysis by: Christopher Daniel So
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: Yes

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives, Copies itself in all available physical drives

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

It modifies the user's Internet Explorer home page into a certain website. This action allows the malware to point to a website which may contain malware, putting the affected computer at greater risk of malware infection.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

Script

Memory Resident:

Yes

Initial Samples Received Date:

25 Jun 2009

Installation

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

  • %System%\winjpg.jpg

(Note: %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.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
regedit = %System%\win.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
CTFMON = %System%\wscript.exe /E:vbs %System%\winjpg.jpg

Other System Modifications

This worm adds the following registry entries:

HKEY_CURRENT_USER
DisplayLogo = 0

HKEY_CURRENT_USER
Timeout = 0

HKEY_CURRENT_USER
Timeout = 0

HKEY_LOCAL_MACHINE
Enabled = 1

HKEY_CURRENT_USER
Window Title = .-~==~-.

HKEY_LOCAL_MACHINE
LimitSystemRestoreCheckpointing = 1

HKEY_LOCAL_MACHINE
DisableSR = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows Script Host\Settings
DisplayLogo = 0

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

HKEY_CLASSES_ROOT\exefile\shell\
Open application\command
(Default) = %System%\win.exe

HKEY_CLASSES_ROOT\exefile\shell\
Scan for virus,s\command
(Default) = %System%\wscript.exe /E:vbs %System%\winjpg.jpg

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
drwtsn32.exe
Debugger = %System%\wscript.exe /E:vbs %System%\winjpg.jpg

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
dwwin.exe
Debugger = %System%\win.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
MSConfig.exe
Debugger = %System%\wscript.exe /E:vbs %System%\winjpg.jpg

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
procexp.exe
Debugger = \win.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
regedit.exe
Debugger = %System%\wscript.exe /E:vbs %System%\winjpg.jpg

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
rstrui.exe
Debugger = %System%\wscript.exe /E:vbs %System%\winjpg.jpg

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
taskmgr.exe
Debugger = %System%\wscript.exe /E:vbs %System%\winjpg.jpg

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusOverride = 1

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wscsvc
Start = 4

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv
Start = 4

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoDriveTypeAutoRun = 0

(Note: The default value data of the said registry entry is 255.)

HKEY_CLASSES_ROOT\VBSFile
FriendlyTypeName = MP3 Audio

(Note: The default value data of the said registry entry is @%System%\wshext.dll,-4802.)

HKEY_CLASSES_ROOT\VBSFile\DefaultIcon
(Default) = %Program Files%\Windows Media Player\wmplayer.exe,-120

(Note: The default value data of the said registry entry is %System%\WScript.exe,2.)

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 0

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = 1

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = 0

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

Propagation

This worm drops the following copies of itself in all physical and removable drives:

  • winfile.jpg

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 /e:vbs winfile.jpg

Web Browser Home Page and Search Page Modification

This worm modifies the user's Internet Explorer home page to the following websites:

  • http://www.freewebtown.com/alrefai/login.live.html

Dropping Routine

This worm drops the following files:

  • %System%\win.exe - detected as BKDR_POISON.YJ

(Note: %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.)

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

6.230.05

FIRST VSAPI PATTERN DATE:

26 Jun 2009

Step 1

Restart in Safe Mode

[ Learn More ]

Step 2

Enable Registry Editor

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

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_CLASSES_ROOT\exefile\shell
    • Open application
  • In HKEY_CLASSES_ROOT\exefile\shell
    • Scan for virus,s
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
    • drwtsn32.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
    • dwwin.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
    • MSConfig.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
    • procexp.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
    • rstrui.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
    • taskmgr.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\Microsoft\Windows\CurrentVersion\Run
    • regedit=%System%\win.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • CTFMON=%System%\wscript.exe /E:vbs %System%\winjpg.jpg
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Scripting Host\Settings
    • DisplayLogo=0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Scripting Host\Settings
    • Timeout=0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Script Host\Settings
    • DisplayLogo=0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Script Host\Settings
    • Timeout=0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Script Host\Settings
    • Enabled=1
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Window Title= .-~==~-.
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Installer
    • LimitSystemRestoreCheckpointing=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\SystemRestore
    • DisableSR=1

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\Security Center
    • From: AntiVirusOverride=1
      To: AntiVirusOverride=0
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wscsvc
    • From: Start=4
      To: Start=2
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wuauserv
    • From: Start=4
      To: Start=2
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • From: NoDriveTypeAutoRun=0
      To: NoDriveTypeAutoRun=255
  • In HKEY_CLASSES_ROOT\VBSFile
    • From: FriendlyTypeName=MP3 Audio
      To: FriendlyTypeName=@%System%\wshext.dll,-4802
  • In HKEY_CLASSES_ROOT\VBSFile\DefaultIcon
    • From: (Default)=%Program Files%\Windows Media Player\wmplayer.exe,-120
      To: (Default)=%System%\WScript.exe,2
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden=0
      To: Hidden=1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: HideFileExt=1
      To: HideFileExt=0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: ShowSuperHidden=0
      To: ShowSuperHidden=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue=0
      To: CheckedValue=1
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • From: Start Page=http://www.freewebtown.com/alrefai/login.live.html
      To: Start Page=about:blank

Step 6

Remove malware files dropped/downloaded by VBS_AUTORUN.JM

    BKDR_POISON.YJ

Step 7

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

[ Learn More ]
[autorun]
shellexecute=Wscript.exe /e:vbs winfile.jpg

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as VBS_AUTORUN.JM. 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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