How to use the removal tools

Home Users

1.Just download the removal tool (.zip file - 3MB), double click on it, chose "Extract all files..." from the File menu, and follow the wizard's instructions. You can use any other archiver, like WinZip. This will create a folder called bd_rem_tool.

2.Inside it, find the program called "bd_rem_tool_gui.exe" (or just "bd_rem_tool_gui") and double click on it. It is very important to extract all the files from the zip archive, and not only bd_rem_tool_gui.exe, because all the other files are needed for the disinfection. Then follow the tool's instructions.

3.If you have Windows Vista with User Acccess Control enabled, or if you are running as a restricted user in Windows XP, right click the "bd_rem_tool_gui" program and choose "Run as Administrator". You will be prompted to enter credentials for an admin account.

4.We recommend a system reboot after the disinfection is complete, to restore full internet access.

5.If you don't already have permanent antivirus protection or if your current antivirus has failed you, consider using the advanced protection tool provided by BitDefender.

Network administrators

The removal kit (.exe file - 13MB)contains the BitDefender Deployment tool and a deployable removal tool to be installed on all the possibly affected computers.


1. Download and install the kit on a network computer (preferably, but not neccessarily, on a known clean one).


2. Run the DptTool from the Desktop shortcut or from the Start menu.



3. On the settings screen, set the reboot option to "Restart if needed".
Set the other options as needed.

General Options

The options in the General Options category allow you to specify the deployment behaviour on the target computers. You can check:

• Notify user before and after deploying the package - to alert the user logged on the target computers about the deployment process. Two dialogs will appear on the user's screen, before and after the deployment process.
• Do not display user interface on the target computers (recommended) To install the package silently in the background. The Windows Installer interface will not be displayed on target computers.
• Use non interactive Authentication - to provide the administrative credentials (username and password) that will be used to authenticate on the target computers.

If the computers to be scanned are set up to not respond to ping (i.e. they have very restrictive firewall policies), set the tool to NOT ping before installing, or the installation will not take place. Click Next to continue.

4.Select the computers to be scanned from the Active Directory listing provided and start the deployment. Please note that the process may take a very long time if some of the computers selected are not online and the "ping before installing" option was de-selected in the previous screen, due to timeouts. Click Start to continue.





5.The Deployment tool will now install and run the Downadup removal tool on the selected computers.


6.The tool will exit cleanly and return "job Finished" if no infection is found.If an infection is found, it will be removed and the affectted machine will be scheduled to reboot after 30 seconds. The return message will also be "Job Finished"Any other situations (target machine not online, removal tool could not be run, etc) will be reported as such.The returned messages can be sorted and saved for later use - e.g. to create a list of machines that need to be cleaned later.

Worm:W32/Downadup.AL

Disinfection

Removal Tools

F-Downadup
Specific tool with heuristics for Downadup worm variants:

• ftp://ftp.f-secure.com/anti-virus/tools/beta/f-downadup.zip

FSMRT
Non-specific detection tool, larger file size:

• ftp://ftp.f-secure.com/anti-virus/tools/beta/fsmrt.zip

Note: these are command line tools, please read the text file included in the ZIP for additional details.

Updates

These are beta tools. Use the following FTP location to determine the file dates:

• ftp://ftp.f-secure.com/anti-virus/tools/beta/

Scanning Options

Downadup makes use of random extension names in order to avoid detection.

During disinfection scanning options should be set to:

• Scan all files

Microsoft Help and Support

Knowledge Base Article 962007 provides numerous details for manual disinfection of Conficker.B (alias Downadup).

• http://support.microsoft.com/kb/962007

Additional Details

Worm:W32/Conficker.AL is a variant of Worm:W32/Downadup.A which is able to spread copies of itself over a network using three different methods: file sharing, exploitation of a vulnerability and exploitation of Windows Autorun.

In addition to attempting to connect to remote sites, Conficker.AL uses stealth techniques to hide its actions, and makes a number of changes to the Windows Registry.

More technical information is also available in the related descriptions:

• Worm:W32/Downadup.A

• Worm:W32/Downadup.gen
• Worm:W32/Downaduprun.A

Installation

Upon execution, Downadup creates copies of itself in:

• %System%\[Random].dll

• %Program Files%\Internet Explorer\[Random].dll

• %Program Files%\Movie Maker\[Random].dll

• %All Users Application Data%\[Random].dll

• %Temp%\[Random].dll

• %System%\[Random].tmp

• %Temp%\[Random].tmp

* Note: [Random] represents a randomly generated name.

Each file's timestamp is amended to match the timestamp of the %System%\kernel32.dll file. The worm then creates autorun entries in the registry, which ensure that a copy of the worm is executed at every system startup.

The worm then attach itself to the following processes:

• svchost.exe

• explorer.exe

• services.exe

Activity

The worm disables a number of system features, in order to facilitate its activities. It disables the following Windows services:

• Windows Automatic Update Service (wuauserv)

• Background Intelligent Transfer Service (BITS)

• Windows Security Center Service (wscsvc)

• Windows Defender Service (WinDefend)

• Windows Error Reporting Service (ERSvc)

• Windows Error Reporting Service (WerSvc)

In addition to disabling these services, it checks to see whether it is running on a Windows Vista machine; if so, it also runs the following command to disable Windows Vista TCP/IP auto-tuning:

• netsh interface tcp set global autotuning=disabled

The worm also hooks the following API's in order to block access when the user attempts to access a long list of domains:

• DNS_Query_A

• DNS_Query_UTF8

• DNS_Query_W

• Query_Main

• sendto

W32.Downadup Removal Tool

• summary

Download Removal Tool|Printer Friendly Page|Feedback

Discovered:

January 13, 2009

Type:

Removal Information

http://www.symantec.com/business/security_response/writeup.jsp?docid=2009-011316-0247-99

This tool is designed to remove the infections of:

• W32.Downadup
• W32.Downadup.B
• W32.Downadup.C

Important:

• If you are on a network or have a full-time connection to the Internet, such as a DSL or cable modem, disconnect the computer from the network and Internet. Disable or password-protect file sharing, or set the shared files to Read Only, before reconnecting the computers to the network or to the Internet. Because this worm spreads by using shared folders on networked computers, to ensure that the worm does not reinfect the computer after it has been removed, Symantec suggests sharing with Read Only access or by using password protection.
  
  For instructions on how to do this, refer to your Windows documentation, or the document: How to configure shared Windows folders for maximum network protection.
  
  For further information on the vulnerability and patches to resolve it please refer to the following document:
  Microsoft Windows Server Service RPC Handling Remote Code Execution Vulnerability
  
  
  
• If you are removing an infection from a network, first make sure that all the shares are disabled or set to Read Only.
  
  
• This tool is not designed to run on Novell NetWare servers. To remove this threat from a NetWare server, first make sure that you have the current virus definitions, and then run a full system scan with the Symantec antivirus product.
  
  

How to download and run the tool

Important: You must have administrative rights to run this tool on Windows NT 4.0, Windows 2000, or Windows XP.

Note for network administrators: If you are running MS Exchange 2000 Server, we recommend that you exclude the M drive from the scan by running the tool from a command line, with the Exclude switch. For more information, read the Microsoft knowledge base article: XADM: Do Not Back Up or Scan Exchange 2000 Drive M (Article 298924).

Follow these steps to download and run the tool:

1. Download the D.exe file from: http://www.symantec.com/content/en/us/global/removal_tool/threat_writeups/D.exe.
2. Save the file to a convenient location, such as your Windows desktop.
3. Optional: To check the authenticity of the digital signature, refer to the "Digital signature" section later in this writeup.
   
   Note: If you are sure that you are downloading this tool from the Security Response Web site, you can skip this step. If you are not sure, or are a network administrator and need to authenticate the files before deployment, follow the steps in the "Digital signature" section before proceeding with step 4.
   
   
4. Close all the running programs.
5. If you are on a network or if you have a full-time connection to the Internet, disconnect the computer from the network and the Internet.
6. If you are running Windows Me or XP, turn off System Restore. For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
   
   How to disable or enable Windows Me System Restore
   
   How to turn off or turn on Windows XP System Restore
   
   
7. Locate the file that you just downloaded.
8. Double-click the D.exe file to start the removal tool.
9. Click Start to begin the process, and then allow the tool to run.
   
   NOTE: If you have any problems when you run the tool, or it does nor appear to remove the threat, restart the computer in Safe mode and run the tool again.
   
   
10. Restart the computer.
11. Run the removal tool again to ensure that the system is clean.
12. If you are running Windows Me/XP, then reenable System Restore.
13. If you are on a network or if you have a full-time connection to the Internet, reconnect the computer to the network or to the Internet connection.
14. Run LiveUpdate to make sure that you are using the most current virus definitions.
    

When the tool has finished running, you will see a message indicating whether the threat has infected the computer. The tool displays results similar to the following:

• Total number of the scanned files
• Number of deleted files
• Number of repaired files
• Number of terminated viral processes
• Number of fixed registry entries
  

What the tool does
The Removal Tool does the following:

• Terminates the associated processes
• Deletes the associated files
• Deletes the registry values added by the threat
  

Switches
The following switches are designed for use by network administrators:
/HELP, /H, /?
Displays the help message.
/NOFIXREG
Disables the registry repair (We do not recommend using this switch).
/SILENT, /S
Enables the silent mode.
/LOG=[PATH NAME]
Creates a log file where [PATH NAME] is the location in which to store the tool's output. By default, this switch creates the log file, FixDwndp.log, in the same folder from which the removal tool was executed.
/MAPPED
Scans the mapped network drives. (We do not recommend using this switch. See the following Note.)
/START
Forces the tool to immediately start scanning.
/EXCLUDE=[PATH]
Excludes the specified [PATH] from scanning. (We do not recommend using this switch. See the following Note.)
/NOCANCEL
Disables the cancel feature of the removal tool.
/NOFILESCAN
Prevents the scanning of the file system.
/NOVULNCHECK
Disables checking for unpatched files.

Important: Using the /MAPPED switch does not ensure the complete removal of the virus on the remote computer, because:

• The scanning of mapped drives scans only the mapped folders. This may not include all the folders on the remote computer, which can lead to missed detections.
• If a viral file is detected on the mapped drive, the removal will fail if a program on the remote computer uses this file.
  

Therefore, you should run the tool on every computer.

The /EXCLUDE switch will only work with one path, not multiple. An alternative is the /NOFILESCAN switch followed by a manual scan with AntiVirus. This will let the tool alter the registry. Then, scan the computer with AntiVirus with current virus definitions. With these steps, you should be able to clean the file system.

The following is an example command line that can be used to exclude a single drive:

"C:\Documents and Settings\user1\Desktop\D.exe" /EXCLUDE=M:\ /LOG=c:\FixDwndp.txt

Alternatively, the command line below will skip scanning the file system, but will repair the registry modifications. Then, run a regular scan of the system with proper exclusions:

"C:\Documents and Settings\user1\Desktop\D.exe" /NOFILESCAN /LOG=c:\FixDwndp.txt

Note: You can give the log file any name and save it to any location.

Digital signature
For security purposes, the removal tool is digitally signed. Symantec recommends that you use only copies of the removal tool that have been directly downloaded from the Symantec Security Response Web site.

If you are not sure, or are a network administrator and need to authenticate files before deployment, you should check the authenticity of the digital signature.

Follow these steps:

1. Go to http://www.wmsoftware.com/free.htm.
2. Download and save the Chktrust.exe file to the same folder in which you saved the removal tool.
   
   Note: Most of the following steps are done at a command prompt. If you downloaded the removal tool to the Windows desktop, it will be easier if you first move the tool to the root of the C drive. Then save the Chktrust.exe file to the root of C as well.
   
   (Step 3 to assume that both the removal tool and Chktrust.exe are in the root of the C drive.)
   
   
3. Click Start > Run.
4. Type one of the following:
   
   Windows 95/98/Me:
   command
   
   Windows NT/2000/XP:
   cmd
   
   
5. Click OK.
6. In the command window, type the following, pressing Enter after typing each line:
   
   cd\
   cd downloads
   chktrust -i D.exe
   
   
7. You should see one of the following messages, depending on your operating system:
   
   Windows XP SP2:
   The Trust Validation Utility window will appear.
   
   Under Publisher, click the Symantec Corporation link. The Digital Signature Details appears.
   Verify the contents of the following fields to ensure that the tool is authentic:
   
   Name: Symantec Corporation
   Signing Time: 05/02/2009 08:25:37 AM
   
   All other operating systems:
   You should see the following message:
   
   Do you want to install and run "D.exe" signed on May 2, 2009 8:25:37 AM and distributed by Symantec Corporation?
   
   Notes:
   The date and time in the digital signature above are based on Pacific time. They will be adjusted your computer's time zone and Regional Options settings.
   
   If you are using Daylight Saving time, the displayed time will be exactly one hour earlier.
   
   If this dialog box does not appear, there are two possible reasons:
   
   The tool is not from Symantec: Unless you are sure that the tool is legitimate and that you downloaded it from the legitimate Symantec Web site, you should not run it.
   
   The tool is from Symantec and is legitimate: However, your operating system was previously instructed to always trust content from Symantec. For information on this and on how to view the confirmation dialog again, read the document: How to restore the Publisher Authenticity confirmation dialog box.
   
   
8. Click Yes or Run to close the dialog box.
9. Type exit, and then press Enter. (This will close the MS-DOS session.)