M December 06, 2008 Virus Alert - WORM_SILLY.DU
WORM_SILLY.DU
   
Virus type: Worm
Destructive:  No
Aliases: Generic.dx (McAfee), W32.SillyFDC (Symantec), TR/Agent.VB.API (Avira), Mal/VBWorm-C (Sophos), Worm:Win32/SillyFDC (Microsoft)
Pattern file needed: 4.789.00
Scan engine needed: 8.500
Overall risk rating: Low
Reported infections: Low
Damage Potential: Low
Distribution Potential: Medium

Description :

This worm drops copies of itself. It sets the attributes of its dropped files.

It creates registry entries to enable its automatic execution at every system startup.

It drops copies of itself in all removable drives. It drops an AUTORUN.INF file to automatically execute dropped copies when the drives are accessed.

It uses enticing file names for its dropped files to trick users into thinking that it is a legitimate application.

Solution :

Identifying the Malware Files

  1. Scan your computer with your Trend Micro antivirus product.
  2. Note the path and file name of all files detected as WORM_SILLY.DU.

Trend Micro customers need to download the latest virus pattern file before scanning their computer. Other users can use Housecall, the Trend Micro online threat scanner.

Terminating the Malware Process

Since this malware uses a file name that is also the file name of a legitimate process, it is necessary to use third party process viewers such as Process Explorer, to isolate the malware process itself.

If the process you are looking for is not in the list displayed by Process Explorer, proceed to the succeeding solution set.

  1. Download Process Explorer.
  2. Extract the contents of the compressed (ZIP) file to a location of your choice.
  3. Execute Process Explorer by double-clicking PROCEXP.EXE.
  4. In the Process Explorer window, locate the process:
    svchost.exe
  5. Right-click the malware process, and choose Properties.
  6. Check if the value for the Current Directory is the following:
    %Windows%\inf
    (Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
  7. If yes, then right-click on the malware process, and click Kill Process Tree.
  8. Close Process Explorer.

*NOTE: On computers running Windows 98 and ME, Windows Task Manager may not show certain processes. You can use a third party process viewer such as Process Explorer to terminate the malware process.

If the process you are looking for is not in the list displayed by Task Manager or Process Explorer, continue with the next solution procedure. If the malware process is in the list displayed by either Task Manager or Process Explorer, but you are unable to terminate it, restart your computer in safe mode.

Removing Autostart Entries from the Registry

This solution deletes/modifies registry keys/entries added/modified by this malware. Before performing the steps below, make sure you know how to back up the registry and how to restore it if a problem occurs. Refer to this Microsoft article for more information about modifying your computer's registry.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry:
    Systems = "%Windows%\inf\svchost.exe"
  4. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>
    Windows>CurrentVersion>Run
  5. In the right panel, locate and delete the entry:
    {6 random characters} = "%Program Files%\Uninstall Information\{5 random characters}.exe"
    (Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)
  6. Close Registry Editor.

Deleting Malware-created AUTORUN.INF/s

  1. Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
  2. In the Named input box, type:
    AUTORUN.INF
  3. In the Look In drop-down list, select a drive, then press Enter.
  4. Select the file, then open using Notepad.
  5. Check if the following lines are present in the file:
    [autorun]
    systemID={8 random characters}
    open={8 random characters}
    shell\open=??(&O)
    shell\open\command={8 random characters}
    shell\open\default=1
    shell\explore=?????(&X)
    shell\explore\Command={8 random characters}
  6. If the lines are present, delete the file.
  7. Repeat steps 3 to 6 for AUTORUN.INF files in the remaining removable drives.
  8. Close Search Results.

Important Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected computers.

Users running other Windows versions can proceed with the succeeding solution set(s).

Running Trend Micro Antivirus

If you are currently running in safe mode, please restart your computer normally before performing the following solution.

Scan your computer with Trend Micro antivirus and delete files detected as WORM_SILLY.DU. To do this, Trend Micro customers must download the latest virus pattern file and scan their computer. Other Internet users can use HouseCall, the Trend Micro online virus scanner.

Trend Micro offers best-of-breed antivirus and content-security solutions for your corporate network or home PC.


For additional information about this threat, see Technical Details.