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.
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 copies of itself into the affected system:
- %User Profile%\{random file name}.exe
- %User Profile%\Passwords.exe
- %User Profile%\Porn.exe
- %User Profile%\Secret.exe
- %User Profile%\Sexy.exe
(Note: %User Profile% is a user's profile folder, where it usually is C:\Documents and Settings\{user name} on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name} on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It drops the following files:
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
{random file name}.exe = "%User Profile%\{random file name}.exe /{random character}"
Other System Modifications
This worm adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\WindowsUpdate\
AU
NoAutoUpdate = "1"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"
(Note: The default value data of the said registry entry is 1.)
Propagation
This worm drops the following copy(ies) of itself in all removable drives:
- {drive letter}:\{random file name}.exe
- {drive letter}:\Passwords.exe
- {drive letter}:\Porn.exe
- {drive letter}:\Secret.exe
- {drive letter}:\Sexy.exe
- {drive letter}:\{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={random filename}.exe
icon={random filename}.exe,0
Download Routine
This worm accesses the following websites to download files:
- ns1.{BLOCKED}ime{number}.{variable}
where {variable} can be any of the following:
It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
NOTES:
It uses the file names of of files with the following extensions:
- .avi
- .bmp
- .doc
- .gif
- .jpe
- .jpg
- .mp3
- .mp4
- .mpg
- .pdf
- .png
- .tif
- .txt
- .wav
- .wma
- .wmv
- .xls
It then sets the attribute of the original folder to Hidden and System to trick users into thinking that the dropped copy is the legitimate folder.
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
Scan your computer with your Trend Micro product and note files detected as WORM_VOBFUS.USSG
Step 3
Restart in Safe Mode
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To restart in Safe Mode:
• For Windows 2000 users
- Restart your computer.
- Press F8 when you see the Starting Windows bar at the bottom of the screen.
- Choose the Safe Mode option from the Windows Advanced Options menu then press Enter.
• For Windows XP users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Windows Advanced Options menu does not appear, try restarting then pressing F8 several times when the POST screen appears.
- Choose the Safe Mode option from the Windows Advanced Options menu then press Enter.
• For Windows Server 2003 users
- Restart your computer.
- Press F8 after Windows starts up. If the Windows Advanced Options menu does not appear, try restarting again and pressing F8 several times afterward.
- On the Windows Advanced Option menu, use the arrow keys to select Safe Mode then press Enter.
• For Windows Vista, Windows 7, and Windows Server 2008 users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Advanced Boot Options menu does not appear, try restarting and then pressing F8 several times after the POST screen is displayed.
- On the Advanced Boot Options menu, use the arrow keys to select the Safe Mode option, and then press Enter.
• For Windows 8, Windows 8.1, and Windows Server 2012 users
- Access the Charms bar by moving your mouse pointer to the upper right corner of the screen.
- Move your mouse pointer down and click Settings>Change your PC Settings.
- In the left panel, click General.
- In the right panel, scroll down to the bottom to find the Advanced startup section, then click the Restart now button and wait for the system to restart.
- In the Advanced Startup menu, click Troubleshoot>Advanced Options>Startup Settings>Restart and wait for the system to restart.
- In the Startup Settings menu, press 4 to enable safe mode.
Step 4
Delete this registry value
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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
- {random file name} = "%User Profile%\{random file name}.exe /{random character}"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
To delete the registry value this malware/grayware created:
- Open Registry Editor.
» For Windows 2000, Windows XP, and Windows Server 2003 users, click Start>Run, type regedit in the text box provided, and then press Enter.
» For Windows Vista, Windows 7, and Windows Server 2008 users, click the Start button, type regedit in the Search input field then press Enter.
» For Windows 8, Windows 8.1, and Windows Server 2012 users, right-click on the lower-left corner of the screen, click Run, type regedit in the text box provided, and then press Enter. - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
{random file name} = "%User Profile%\{random file name}.exe /{random character}" - In the left panel, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Policies>Microsoft>Windows>WindowsUpdate>AU - In the right panel, locate and delete the entry:
NoAutoUpdate = "1" - Close Registry Editor.
Step 5
Restore these modified registry values
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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\CurrentVersion\Explorer\Advanced
- From: ShowSuperHidden = "0"
To: ShowSuperHidden = "1"
To restore registry values this malware/grayware modified:
- Open Registry Editor. To do this:
- On Windows 2000, XP, and Server 2003:
Click Start>Run, type REGEDIT in the text box provided, and then press Enter. - On Windows Vista, 7, and Server 2008:
Click the Start button, type REGEDIT in the Search input field then press Enter. - On Windows 8, 8.1, and Server 2012:
Right-click on the lower left corner of the screen and click Run, type REGEDIT in the Run input field, and then press Enter.
- In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>Advanced - In the right panel, locate the registry value:
ShowSuperHidden = "0" - Right-click on the value name and choose Modify. Change the value data of this entry to:
ShowSuperHidden = "1" - Close Registry Editor.
Step 6
Search and delete AUTORUN.INF files created by WORM_VOBFUS.USSG that contain these strings
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[autorun]
open={random filename}.exe
icon={random filename}.exe,0
To identify and delete AUTORUN.INF files created:
For Windows 2000, Windows XP, and Windows Server 2003:
- Right-click the Start button then choose Search... or Find..., depending on the version of Windows you are running.
- In the File name* input box, type:
AUTORUN.INF - In the Look in: drop-down list, select a drive, then press Enter.
- Select the file, then open using Notepad.
- Check if the following lines are present in the file:
[autorun]
open={random filename}.exe
icon={random filename}.exe,0
- If the lines are present, delete the file.
- Repeat steps 3 to 6 for the remaining AUTORUN.INF files in other remaining removable drives.
- Close Search Results.
*Note: The file name input box title varies depending on the Windows version (e.g.
Search for files or folders named or
All or part of the file name.).
For Windows Vista, Windows 7, Windows Server 2003, Windows 8, Windows 8.1, and Windows Server 2012:
- Open a Windows Explorer window.
- For Windows Vista, 7, and Server 2008 users, click Start>Computer.
- For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
- In the Search Computer/This PC input box, type:
AUTORUN.INF - Select the file, then open using Notepad.
- Check if the following lines are present in the file:
[autorun]
open={random filename}.exe
icon={random filename}.exe,0
- If the lines are present, delete the file.
- Repeat steps 3 to 5 for the remaining AUTORUN.INF files in other remaining removable drives.
- Close Search Results.
Step 7
Search and delete this file
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There may be some 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.
To manually delete a malware/grayware file from an affected system:
• For Windows 2000, Windows XP, and Windows Server 2003:
- Right-click Start then click Search....
- In the File name* input box, type the following:
- In the Look In drop-down list, select My Computer then press Enter.
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).
• For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:
- Open a Windows Explorer window.
- For Windows Vista, 7, and Server 2008 users, click Start>Computer.
- For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
- In the Search Computer/This PC input box, type:
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: Read the following Microsoft page if these steps do not work on Windows 7.
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_VOBFUS.USSG. 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.
