W32.Coflop@mm

SUMMARY

W32.Coflop@mm is a mass-mailing worm that uses MAPI to send itself to all the contacts in the Microsoft Outlook Address Book. The worm also attempts to spread itself through the KaZaA file-sharing networks and the floppy disk. The email has the following characteristics:

Subject: Back Up your Data to Floppy Today!
Message:
This program will allow you to back up 3 Times as much data to your floppy
disk! Up to 9MB!!! (compared to 2mb disks) so back up your system today with this free software.
Attachment: Sol.exe

This threat is written in the Microsoft Visual Basic programming language.

Protection

• Virus Definitions (LiveUpdate™ Weekly) January 8, 2003
• Virus Definitions (Intelligent Updater) January 7, 2003

TECHNICAL DETAILS

When W32.Coflop@mm runs, it does the following:

1. Displays a fake message:
   
   
   
   
2. Copies itself as:
   • C:WindowsRegedit.exe
   • C:WindowsSystem32Sol.exe
   • C:WindowsSystem32Solbackup.exe
   • D:Setup.exe - The attributes of this file are set to Hidden and Read_only
   • A:CopyFloppy.exe
     
     
3. Creates a file, D:Cf.reg, which contains the section:
   
   [autorun]
   open = setup.exe
   icon = setup.exe
   
4. Overwrites the following files with the string "copyfloppy":
   • C:WindowsUninst.exe
   • C:WindowsSt5unst.exe
   • C:WindowsTwunk_32.exe
   • C:WindowsClock.avi
     
     
5. Uses MAPI to send itself to all the contacts in Microsoft Outlook Address Book. The email has the following characteristics:
   
   Subject: Back Up your Data to Floppy Today!
   Message:
   This program will allow you to back up 3 Times as much data to your floppy
   disk! Up to 9MB!!! (compared to 2mb disks) so back up your system today with this free software.
   Attachment: Sol.exe
   
6. If the system date is Jan. 2, Feb. 3, Mar. 4, Apr. 5, May 6, Jun. 7, Jul. 8, Aug. 9, Sep. 10, Oct. 11, Nov. 12, or Dec. 13, the worm does the following:
   • Displays the following message:
     
     
     
     
   • Copies itself as:
     c:CopyFloppy(1).exe
     c:CopyFloppy(2).exe
     c:CopyFloppy(3).exe
     c:CopyFloppy(4).exe
     c:CopyFloppy(5).exe
     c:CopyFloppy(6).exe
     c:CopyFloppy(7).exe
     c:CopyFloppy(8).exe
     c:CopyFloppy(9).exe
     c:CopyFloppy(10).exe
     c:CopyFloppy(11).exe
     c:CopyFloppy(12).exe
     c:CopyFloppy(13).exe
     c:CopyFloppy(14).exe
     c:CopyFloppy(15).exe
     c:CopyFloppy(16).exe
     c:CopyFloppy.exe
     
     
   • Adds the value:
     
     CopyFloppy c:Program FilesInstall.exe
     
     to the registry key:
     
     HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
     
     NOTE: Due to a bug, the worm does not copy itself as C:Program FilesInstall.exe. Therefore, the worm does not run when you restart Windows.
     
     
   • Adds the value:
     
     DownloadDir C:
     
     to the registry key:
     
     HKEY_CURRENT_USERSoftwareKaZaaLocalContent

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

REMOVAL

These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions.
2. Restart the computer in Safe mode.
3. Run a full system scan and delete all the files detected as W32.Coflop@mm.
4. Restore the following files overwritten by the worm from the backup, if necessary:
   • C:WindowsUninst.exe
   • C:WindowsSt5unst.exe
   • C:WindowsTwunk_32.exe
   • C:WindowsClock.av
   • C:WindowsRegedit.exe
5. Reverse the changes that the worm added to the registry.
   

For specific details on each of these procedures, read the following instructions.

1. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:

• Running LiveUpdate, which is the easiest way to obtain the virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate), in the "Protection" section, at the top of this writeup.
• Downloading the definitions using the Intelligent Updater. The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater), in the "Protection" section, at the top of this writeup.
  
  The Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

2. Restarting the computer in Safe mode

Restart the computer in Safe mode. All the Windows 32-bit operating systems, except for Windows NT, can be restarted in Safe mode. For instructions on how to do this, read the document, "How to start the computer in Safe Mode."

3. Scanning for and deleting the infected files

1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
   • For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
   • For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec Corporate antivirus product is set to scan All Files."
2. Run a full system scan.
3. If any files are detected as infected with W32.Coflop@mm, click Delete.

4. Restoring overwritten files
The following documents provide general instructions on how to extract files. This information is provided for your convenience. The exact steps may slightly vary depending on the configuration of your operation system, the location of the files, and so on. For additional information, read the Help files, contact Microsoft, or refer to the following Windows documentation:

• The Microsoft Knowledge Base article, "How to Extract Original Compressed Windows Files," Article ID Q129605, has detailed information for Windows 95/98/Me.
• "How to extract files in Windows 98 and Windows Me"
• "How to extract files using Windows 2000 or Windows NT 4.0"
• "How to restore system files in Windows XP"

5. Reversing the changes made to the registry

CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit, and then click OK. (The Registry Editor opens.)
3. Navigate to the following key:
   
   HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the value:
   
   CopyFloppy
   
5. Navigate to the following key:
   
   HKEY_CURRENT_USERSoftwareKaZaaLocalContent
   
6. In the right pane, delete the value:
   
   DownloadDir
   
7. Click Registry, and click Exit.