TROJ_MEDFOS.YYJU

To restore registry values this malware/grayware modified:

1. 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.
2. In the left panel, double-click the following:
   HKEY_LOCAL_MACHINE>SYSTEM>ControlSet001>Services>6to4>Parameters
3. In the right panel, locate the registry value:
   ServiceDll = "antivirusupdate.dll"
4. Right-click on the value name and choose Modify. Change the value data of this entry to:
   ServiceDll = "{random values}"
5. In the left panel, double-click the following:
   HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Prefetcher
6. In the right panel, locate the registry value:
   TracesProcessed = "4"
7. Right-click on the value name and choose Modify. Change the value data of this entry to:
   TracesProcessed = "9"
8. Again In the right panel, locate the registry value:
   TracesSuccessful = "3"
9. Right-click on the value name and choose Modify. Change the value data of this entry to:
   TracesSuccessful = "6"
10. Again In the right panel, locate the registry value:
    LastTraceFailure = "2"
11. Right-click on the value name and choose Modify. Change the value data of this entry to:
    LastTraceFailure = "4"
12. Close Registry Editor.

To manually delete a malware/grayware file from an affected system:

• For Windows 2000, Windows XP, and Windows Server 2003:

1. Right-click Start then click Search....
2. In the File name* input box, type the following:
   
   • %System%\antivirusupdate.dll
   • %Windows%\Prefetch\CWSANDBOX.EXE-00162164.pf
3. In the Look In drop-down list, select My Computer then press Enter.
4. 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:

1. 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.
2. In the Search Computer/This PC input box, type:
   
   • %System%\antivirusupdate.dll
   • %Windows%\Prefetch\CWSANDBOX.EXE-00162164.pf
3. 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.