Analysis by: Kathleen Notario
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via removable drives

This worm uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

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 removable drives.

  TECHNICAL DETAILS

File Size: 200,704 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 02 Nov 2009

Installation

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

  • %System%\WinSit.exe
  • %System%\config\Win.exe
  • %Windows%\Help\Other.exe
  • %Windows%\SVIQ.exe
  • %Windows%\dc.exe
  • %Windows%\inf\Other.exe
  • %Windows%\system\Fun.exe

(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.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

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
imscmig = %Windows%\imscmig.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dc2k5 = %Windows%\SVIQ.EXE

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Fun = %Windows%\system\Fun.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dc = %Windows%\dc.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
run = %System%\config\Win.exe

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 = %Windows%\inf\Other.exe

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = Explorer.exe %System%\WinSit.exe

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

Propagation

This worm 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 removable drives.

Dropping Routine

This worm drops the following files:

  • %Windows%\wininit.ini - non-malicious file

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 6.596.02
VSAPI PATTERN Date: 02 Nov 2009
VSAPI PATTERN Date: 11/2/2009 12:00:00 AM

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

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • imscmig=%Windows%\imscmig.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dc2k5=%Windows%\SVIQ.EXE
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Fun=%Windows%\system\Fun.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dc=%Windows%\dc.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    • run=%System%\config\Win.exe

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\Windows NT\CurrentVersion\Windows
    • From: load=%Windows%\inf\Other.exe
      To: blank
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell=Explorer.exe %System%\WinSit.exe
      To: Explorer.exe

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.
  • %Windows%\wininit.ini

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_IMAUT.ERO. 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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