WORM_EMBEDDED.GV
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This worm arrives by connecting affected removable drives to a system. 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 drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.
TECHNICAL DETAILS
Arrival Details
This worm arrives by connecting affected removable drives to a system.
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 file(s)/component(s):
- %Windows%\Tasks\At1.job
- %System%\28463\svchost.001
- %System%\setting.ini
- %System%\setup.ini
(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:
- %Windows%\regsvr.exe
- %System%\regsvr.exe
- %System%\svchost .exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.)
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
Msn Messsenger = "%System%\regsvr.exe"
It modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe regsvr.exe"
(Note: The default value data of the said registry entry is Explorer.exe.)
Other System Modifications
This worm adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
WorkgroupCrawler\Shares
shared = "{shared folder}\New Folder .exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NofolderOptions = "0"
Propagation
This worm searches the network for the following shared networks onto which it attempts to drop copies of itself:
- New Folder .exe
- regsvr.exe
It searches for folders in all physical and removable drives then drops copies of itself inside the folder as {folder name}.EXE.
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=regsvr.exe
Shellexecute=regsvr.exe
Shell\Open\command=regsvr.exe
Shell=Open
Download Routine
This worm connects to the following website(s) to download and execute a malicious file:
- http://{BLOCKED}o.com/setting.doc
- http://{BLOCKED}o.com/setting.doc
- http://www.{BLOCKED}o.com/setting.doc
- http://www.{BLOCKED}o.com/setting.xls
It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
As of this writing, the said sites are inaccessible.
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
Scan your computer with your Trend Micro product and note files detected as WORM_EMBEDDED.GV
Step 3
Restart in Safe Mode
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\CurrentVersion\Explorer\WorkgroupCrawler\Shares
- shared = {shared folder}\New Folder.exe
- shared = {shared folder}\New Folder.exe
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
- DisableTaskMgr = 0
- DisableTaskMgr = 0
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
- DisableRegistryTools = 1
- DisableRegistryTools = 1
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
- NofolderOptions = 0
- NofolderOptions = 0
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Msn Messsenger = %System%\regsvr.exe
- Msn Messsenger = %System%\regsvr.exe
Step 5
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Shell = Explorer.exe regsvr.exe
To: Shell = Explorer.exe
- From: Shell = Explorer.exe regsvr.exe
Step 6
Search and delete these files
Step 7
Search and delete the file detected as WORM_EMBEDDED.GV
Step 8
Search and delete AUTORUN.INF files created by WORM_EMBEDDED.GV that contain these strings
Open=regsvr.exe
Shellexecute=regsvr.exe
Shell\Open\command=regsvr.exe
Shell=Open
Step 9
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_EMBEDDED.GV. 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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