W32.HLLW.Yoof

SUMMARY

W32.HLLW.Yoof is a worm that spreads by using the KaZaA file-sharing program. It tricks KaZaA users into downloading and executing the worm.

When W32.HLLW.Yoof runs, the worm copies itself as %system%SystemConfig.exe and creates the %system%Media shared folder. It then copies itself to this folder using numerous file names, some of which are:

• Email Bomber.exe
• FileServer.exe
• Kazaa Clone.exe
• Napster Clone.exe
• Winmx.exe
• Website Hacker.exe
• Hotmail Hacker.exe
• Windows Hacker.exe

Protection

• Virus Definitions (LiveUpdate™ Weekly) August 22, 2002
• Virus Definitions (Intelligent Updater) August 22, 2002

Threat Assessment

Wild

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

Damage

• Damage Level: Low

Distribution

• Distribution Level: Medium
• Shared Drives: Attempts to spread using the shared folder that is used by the KaZaA file-sharing program.

TECHNICAL DETAILS

When it is run, W32.HLLW.Yoof does the following:

It copies itself as %system%SystemConfig.exe.

NOTE: %system% is a variable. The worm locates the System folder and copies itself to that location. By default this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).

The worm adds the value

Windows System Configure    %System%SystemConfig.exe

to these registry keys:

HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
HKEY_LOCAL_MACHINESoftwareMicrosoftWindows
CurrentVersionRunServices

so that it runs each time that you start Windows.

Some variants also download a file named C:Uninstall.exe. If the worm downloads and executes this file, it then downloads a file named C:Unwise.exe and sends an ICQ page to the virus creator.

The worm then creates the%system%Media folder. It then configures this folder to be a shared KaZaA folder by making the following registry modifications:

• It adds the values
  
  Dir0 %system%Media
  Dir1 %system%Media
  Dir2 012345:%System%Media
  Disable Sharing 0
  
  to the registry key
  
  HKEY_CURRENT_USERSoftwareKazaaLocalContent
  
• It adds the values
  
  DlDir0 012345:%system%Media
  DlDir1 %system%Media
  DlDir99 012345:%system%Media
  
  to the registry key
  
  HKEY_CURRENT_USERSoftwareKazaaTransfer
  
• It adds the value
  
  Sharedir %System%Media
  
  to the registry key:
  
  HKEY_LOCAL_MACHINESoftwareKazaaCloudload

Finally, it copies itself to %system%Media as the following files:

• Jenna Jamison Dildo Humping.exe
• Pamela Anderson And Tommy Lee Home Video.exe
• Alicia Silverstone Payboy Nude.exe
• Kama Sutra Tetris.exe
• Flash Golf.exe
• Hoes For You Solitare.exe
• Bingo.exe
• Irc Client.exe
• Mirc 7.0.exe
• Email Bomber.exe
• FileServer.exe
• Kazaa Clone.exe
• Napster Clone.exe
• Winmx.exe
• Website Hacker.exe
• Hotmail Hacker.exe
• Windows Hacker.exe
• Free Porn.exe
• Free Mpegs.exe
• Free Pics.exe
• Xbox Emulator.exe
• Britney Spears Dance Beat.exe
• Shakira Dancing.exe
• J.Lo Bikini Screensaver.exe
• Universal Game Crack.exe
• Soldier Of Fortune 2 Mutiplayer Serial Hack.exe
• Play Games Online For FREE.exe
• Win A Ps2.exe
• Win An Xbox.exe
• Ps2 Emulator.exe
• Ps2 Iso 2 Rom Converter.exe
• Xbox Iso 2 Rom Converter.exe
• The Sims Game Crack.exe
• Working Iso Burner.exe
• Winzip.exe
• Winrar.exe
• Winace.exe
• System Monitor.exe
• Warcraft 3 Battle.net Crack.exe
• DDos Client.exe

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

NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions, run a full system scan, and delete all files that are detected as W32.HLLW.Yoof.
2. Delete the values that the worm added to the registry.
   

For details on how to do this, read the following instructions.

To scan for and delete the infected files:

1. Obtain the most recent virus definitions. There are two ways to do this:
   • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
   • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.
     
     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. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
   • Norton AntiVirus consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • Symantec enterprise antivirus products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
3. Run a full system scan.
4. If any files are detected as infected by W32.HLLW.Yoof, click Delete.

To delete the values that the worm added 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 only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to each of these keys:
   
   HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindows
   CurrentVersionRunServices
   
   and in the right pane, delete the value
   
   Windows System Configure    %system%SystemConfig.exe
   
4. Navigate to the key
   
   HKEY_CURRENT_USERSoftwareKazaaLocalContent
   
5. In the right pane, delete these values:
   
   Dir0 %system%Media
   Dir1 %system%Media
   Dir2 012345:%System%Media
   Disable Sharing 0
   
6. Navigate to the key
   
   HKEY_CURRENT_USERSoftwareKazaaTransfer
   
7. In the right pane, delete these values
   
   DlDir0 012345:%system%Media
   DlDir1 %system%Media
   DlDir99 012345:%system%Media
   
8. Navigate to the key
   
   HKEY_LOCAL_MACHINESoftwareKazaaCloudload
   
9. In the right pane, delete the value
   
   Sharedir %System%Media
   
10. Exit the Registry Editor.