W32.HLLP.Spreda.B

SUMMARY

W32.HLLP.Spreda.B is a high-level language virus that spreads through KaZaA networks by infecting the .exe files in the KaZaA download folder. Under some conditions, W32.HLLP.Spreda.B inserts a password stealer onto the system.

NOTE: Virus definitions dated prior to September 30, 2003 may detect this worm as W32.HLLP.Savno.

Protection

• Virus Definitions (LiveUpdate™ Weekly) October 1, 2003
• Virus Definitions (Intelligent Updater) September 29, 2003

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Medium
• Modifies Files: Infects all the files in the KaZaA download folder that have a file size larger than 102,400 bytes and smaller than 10,385,024 bytes.
• Releases Confidential Info: May steal passwords.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Once W32.HLLP.Spreda.B is activated, it creates the folder %Windir%Winww.

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Note: %Windir% is a variable. The virus locates the Windows installation folder (by default, this is C:Windows or C:Winnt) and copies itself to that location.

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Infection
W32.HLLP.Spreda.B infects any .exe files it finds in the KaZaA download folder, if the files are larger than 102,400 bytes and smaller than 10,385,024 bytes.

Insertion
If the file %Windir%Winset.ini does not exist, W32.HLLP.Spreda.B does the following:

1. Creates %Windir%Winset.ini.
   
   
2. Searches for a file named <file name>.url in the folders:
   
   C:Document and Settings
   %Windir%Temporary Internet Files
   
   where <file name> includes one of the following:
   
   password
   log on
   log-on
   logon
   login
   bank
   sign-on
   sign on
   building society
   registration
   register
   lloyds
   
   And if such a file exists, it will drop the %Windir%Savenow.exe file and create the registry value:
   
   "Savenow"="%windir%savenow.exe"
   
   under the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   so that Savenow.exe is executed each time you start Windows.
   

Original host
Next, W32.HLLP.Spreda.B writes the original host to %Windir%winwwSn??.exe, where ?? is in the range 00 up to and including 50.

If fewer than 50 infected hosts have been executed, the worm will execute the original host %Windir%WinwwSn??.exe.

Savenow.exe
Savenow.exe is a password stealer that, once activated, deletes all the Sn??.exe files from: %Windir%Winww, and then searches periodically for Internet Explorer windows, where the title bar includes one of the following:

password
log on
log-on
logon
login
bank
sign-on
sign on
building society
registration
register
lloyds

If found, Savenow.exe will grab the URL displayed in that window, and then send it to an Internet site using a standard HTTP request.

Savenow.exe is detected as W32.HLLP.Spreda.B.spy.

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

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

1. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Do one of the following:
   • Windows 95/98/Me: Restart the computer in Safe mode.
   • Windows NT/2000/XP: End the Trojan process.
4. Run a full system scan, repair any files detected as W32.HLLP.Spreda.B, and then delete the files detected as W32.HLLP.Spreda.B.spy.
5. Reverse the changes that the Trojan made to the registry.
   

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

1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

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"

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.

2. 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 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).
• 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).
  
  The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. Restarting the computer in Safe mode or ending the Trojan process

Windows 95/98/Me
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, read the document, "How to start the computer in Safe Mode."

Windows NT/2000/XP
To end the Trojan process:
1. Press Ctrl+Alt+Delete once.
2. Click Task Manager.
3. Click the Processes tab.
4. Double-click the Image Name column header to alphabetically sort the processes.
5. Scroll through the list and look for Savenow.exe.
6. If you find the file, click it, and then click End Process.
7. Exit the Task Manager.
   

4. 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. Repair any files detected as W32.HLLP.Spreda.B, and then delete the files detected as W32.HLLP.Spreda.B.spy.

5. Reversing the changes made to the registry

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WARNING: Symantec strongly recommends that you back up the registry before making 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.

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1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit
   
   Then click OK. (The Registry Editor opens.)
   
   
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete the value:
   
   "Savenow"="%windir%savenow.exe"
   
   
5. Exit the Registry Editor.