WORM_IMAUT.SME
Virus:Win32/Lopown.B (Microsoft)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This worm arrives by accessing affected shared networks. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
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. The sent messages contains a link where a copy of the malware may be downloaded.
TECHNICAL DETAILS
Arrival Details
This worm arrives by accessing affected shared networks.
It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Installation
This worm drops the following non-malicious files:
- %Windows%\wininit.ini
- %System%\Xpen.dat
- %System%\Penx.dat
(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.)
It drops the following copies of itself into the affected system:
- %System%\config\Win.exe
- %Windows%\system\Fun.exe
- %Windows%\inf\Other.exe
- %Windows%\Help\Other.exe
- %System%\WinSit.exe
- %Windows%\dc.exe
- %Windows%\SVIQ.EXE
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Windows% is the Windows folder, which is usually C:\Windows.)
It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.
It injects itself into the following processes as part of its memory residency routine:
- 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\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.
The sent messages contain the following link(s), where a copy of the malware may be downloaded:
- http://{BLOCKED}ivb.googlepages.com/ND.txt
It sends messages that contain links to sites hosting remote copies of itself using the following instant-messaging (IM) applications:
- Yahoo Messenger
NOTES:
It drops the following copy of itself into network shares:
- Fun.exe
SOLUTION
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 2
Identify and delete files detected as WORM_IMAUT.SME using either the Startup Disk or Recovery Console
Step 3
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\CurrentVersion\Run
- imscmig = %Windows%\imscmig.exe
- imscmig = %Windows%\imscmig.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
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- dc = %Windows%\dc.exe
- dc = %Windows%\dc.exe
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
- run = %System%\config\Win.exe
- run = %System%\config\Win.exe
Step 4
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out 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 =
- From: load = %Windows%\inf\Other.exe
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Shell = Explorer.exe %Windows%system32\WinSit.exe
To: Shell = Explorer.exe
- From: Shell = Explorer.exe %Windows%system32\WinSit.exe
Step 5
Search and delete these files
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_IMAUT.SME. 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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