W32.HLLP.Spreda.B

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_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   so that Savenow.exe is executed each time you start Windows.
   

Original host
Next, W32.HLLP.Spreda.B writes the original host to %Windir%\winww\Sn??.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%\Winww\Sn??.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":

• Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
• 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.
• Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
• Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
• Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
• Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
• If a 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate compromised computers quickly to prevent threats from spreading further. 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.
• If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
• For further information on the terms used in this document, please refer to the Security Response glossary.

Summary