WORM_IMAUT.VN
Windows 2000, Windows XP, Windows Server 2003

Threat Type: Worm
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This worm arrives via removable drives.
It 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.
TECHNICAL DETAILS
Arrival Details
This worm arrives via removable drives.
It may arrive via network shares.
Installation
This worm drops the following non-malicious files:
- %System%\Penx.dat
- %System%\Xpen.dat
- %Windows%\wininit.ini
(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 drops the following copies of itself into the affected system:
- %Windows%\dc.exe
- %Windows%\SVIQ.EXE
- %Windows%\Help\Other.exe
- %Windows%\inf\Other.exe
- %Windows%\system\Fun.exe
- %System%\WinSit.exe
- %System%\config\Win.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %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.)
It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.
It injects codes into the following process(es):
- lsass.exe
- csrss.exe
- svchost.exe
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
run = %System%\config\Win.exe
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dc = %Windows%\dc.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
It modifies the following registry entry(ies) to enable its 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 sends copies of itself to target recipients using the following instant-messaging (IM) applications:
- Yahoo! Messenger
It sends the following messages using the aforementioned Instant Messaging applications:
Chuc mung, ban da tam thoi thoat khoi Worm DungCoi
Olalala, may tinh cua ban da dinh Worm DungCoi...........
It sends messages that contain links to sites hosting remote copies of itself using the following instant-messaging (IM) applications:
- http://{BLOCKED}ivb.googlepages.com/NWB.txt
NOTES:
It drops the following copy of itself into network shares:
- Fun.exe
SOLUTION
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 delete files detected as WORM_IMAUT.VN using either the Startup Disk or Recovery Console
Step 3
Search and delete this file
Step 4
Delete this registry value
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
- run = %System%\config\Win.exe
- run = %System%\config\Win.exe
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- dc = %Windows%\dc.exe
- dc = %Windows%\dc.exe
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- dc2k5 = %Windows%\SVIQ.EXE
- dc2k5 = %Windows%\SVIQ.EXE
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Fun = %Windows%\system\Fun.exe
- Fun = %Windows%\system\Fun.exe
Step 5
Restore this modified registry value
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: load = blank
- From: load = %Windows%\inf\Other.exe
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Shell = Explorer.exe %System%\WinSit.exe
To: Shell = Explorer.exe
- From: Shell = Explorer.exe %System%\WinSit.exe
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_IMAUT.VN. 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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