VBS_OTORUN.SQ

 Analysis by: Roland Dela Paz

 ALIASES:

Symantec : VBS.Runauto; Mcafee : VBS/Autorun.worm.k

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This worm adds registry entries to enable its automatic execution at every system startup.

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:

15,281,796 bytes

File Type:

Script

Memory Resident:

Yes

Initial Samples Received Date:

11 Jan 2011

Installation

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

  • %WINDOWS%\Thumbs.vbs

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
avctrl = wscript.exe %windows%\Thumbs.vbs

Other System Modifications

This worm modifies the following registry entries:

HKEY_CLASSES_ROOT\VBSFile
@ = Configuration Script

(Note: The default value data of the said registry entry is VBScript Script File.)

Propagation

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

  • Thumbs.vbs

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]
open=wscript.exe Thumbs.vbs
icon=0
shell\install = &Install
shell\install\command = wscript.exe Thumbs.vbs
shell\uninstall = &UnInstall
shell\uninstall\command = wscript.exe Thumbs.vbs
shell\readme = &Read Me
shell\readme\command = wscript.exe Thumbs.vbs
shell\help = &Help
shell\help\command = wscript.exe Thumbs.vbs
shell\Open = &Open
shell\Open\command = wscript.exe Thumbs.vbs
shell\Open\Default=1
shell\Run = &Run
shell\Run\command = wscript.exe Thumbs.vbs
shell\Run\Default=1
shell\explore=Explorer
shell\explore\Command=Explorer.exe

  SOLUTION

Minimum Scan Engine:

8.900

Step 1

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

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

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
    • avctrl = wscript.exe %windows%\Thumbs.vbs

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_CLASSES_ROOT\VBSFile
    • From: @ = Configuration Script
      To: @ = VBScript Script File

Step 5

Search and delete AUTORUN.INF files created by VBS_OTORUN.SQ that contain these strings

[ Learn More ]
[AUTORUN]
open=wscript.exe Thumbs.vbs
icon=0
shell\install = &Install
shell\install\command = wscript.exe Thumbs.vbs
shell\uninstall = &UnInstall
shell\uninstall\command = wscript.exe Thumbs.vbs
shell\readme = &Read Me
shell\readme\command = wscript.exe Thumbs.vbs
shell\help = &Help
shell\help\command = wscript.exe Thumbs.vbs
shell\Open = &Open
shell\Open\command = wscript.exe Thumbs.vbs
shell\Open\Default=1
shell\Run = &Run
shell\Run\command = wscript.exe Thumbs.vbs
shell\Run\Default=1
shell\explore=Explorer
shell\explore\Command=Explorer.exe

Step 6

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