W32.HLLW.Winur

SUMMARY

W32.HLLW.Winur is a worm that uses the KaZaA and WinMX file-sharing programs to spread itself. This worm can also perform Distributed Denial of Service (DDoS) attacks.

W32.HLLW.Winur is written in Microsoft Visual Basic, version 6.

Protection

• Virus Definitions (LiveUpdate™ Weekly) February 5, 2003
• Virus Definitions (Intelligent Updater) February 3, 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: Low

Distribution

• Distribution Level: Medium
• Shared Drives: Attempts to spread via KaZaA and WinMX file-sharing programs

TECHNICAL DETAILS

When W32.HLLW.Winur is executed, it does the following:

1. Copies itself as these two files:
   • C:klez_removal.exe
   • A:Important - read this.doc <62 spaces> .exe
     
     NOTE: There are 62 blank spaces between the first extension (.doc) and the second extension (.exe) to make you think that the file is a Microsoft Word document when it is actually an executable file.
     
     
2. Creates the hidden folder, C:Winrun.
   
   
3. Copies itself to the C:Winrun folder as the following files:
   • .exe
   • Adobe Photoshop cracker.exe
   • Age of Empire crack.exe
   • Age of Mythology cracker.exe
   • All Microsoft games cracker.exe
   • Anastacia game.exe
   • AOL hacker.exe
   • AOL password stealer.exe
   • Britney spears game.exe
   • Bugbear remover.exe
   • Christina Aguilera game.exe
   • Die another Day DVD full.exe
   • Die another day flash movie(1).exe
   • Die another day flash movie.exe
   • Dvd ripper.exe
   • EA games Keygen.exe
   • Esafe desktop protection crack.exe
   • Frontpage cracker.exe
   • Hotmail account hacker in 30 minutes.exe
   • Hotmail hacker.exe
   • Hotmailhacker v1.0.exe
   • ICQ hacker.exe
   • ICQ password stealer.exe
   • Jack the ripper v1.0.exe
   • Jackie chan dvd collection.exe
   • James Bond game - Die another day.exe
   • John the ripper v1.0.exe
   • Justin Timberlake Debute movie.exe
   • kazaa.exe
   • kazaa.url.exe
   • Klez fixtool.exe
   • Lord of the rings VCD.exe
   • Love calculator.exe
   • Mcafee virusscanner crack.exe
   • Microangelo cracker.exe
   • Most important hacker tool ever!.exe
   • msconfig.exe
   • MSN Messenger commercial cracker.exe
   • MSN Password stealer.exe
   • MXlinx 0.30 crack.exe
   • Nikki cox game and movie.exe
   • Norton antivirus cracker.exe
   • Office XP license cracker.exe
   • pornmovie (hardcore sex adult asian).exe
   • Red Alert cracker - All versions.exe
   • Rollercoaster tycoon cracker.exe
   • Shriek DVD crack patch.exe
   • Stop the war (intro).exe
   • Super 2000key keygen.exe
   • Theme park world cracker.exe
   • UnIcOrn Gift.exe
   • Warcraft 3 cracker.exe
   • Website hacker v1.0.exe
   • Windows Me crack.exe
   • Windows XP license cracker.exe
   • Yaha Fixtool.exe
     
     
4. Adds the value:
   
   msconfig C:winrunmsconfig.exe
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   so that the worm runs when you start Windows.
   
   
5. Adds the value:
   
   winrun c:winrunmsconfig.exe
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersion
   RunServices
   
   so that the worm runs when you start Windows.
   
   
6. Adds the value:
   
   "IMWarning"="(M)Warning: The person who you are talking to is infected with a virus. Send him the removal tool that can be found in C:klez_removal.exe(M)"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftMessengerServicePolicies
   
   This generates a warning message in MSN Messenger encouraging the user, with the infected system, to send a copy of the worm to his/her contacts.
   
   
7. Decreases the security level of the KaZaA file-sharing software (if you have the software installed), by adding or modifying the following values:
   • ScanFolder 0x00000001
     
     in these registry keys:
     
     HKEY_CURRENT_USERSoftwareKAZAA\Advanced
     HKEY_USERS.DEFAULTSoftwareKAZAAAdvanced
     
   • IgnoreAll 0x00000001
     
     in these registry keys:
     
     HKEY_CURRENT_USERSoftwareKAZAAInstantMessaging
     HKEY_USERS.DEFAULTSoftwareKAZAAInstantMessaging
     
   • AutoConnected 0x00000001
     
     in these registry keys:
     
     HKEY_CURRENT_USERSoftwareKAZAAUserDetails
     HKEY_USERS.DEFAULTSoftwareKAZAAUserDetails
     
   • FolderWarning 0x00000000
     
     in these registry keys:
     
     HKEY_CURRENT_USERSoftwareKAZAASettings
     HKEY_USERS.DEFAULTSoftwareKAZAASettings
     
   • The following values:
     
     dir0 13263:C:Winrun
     DisableSharing 0x00000000
     
     in these registry keys:
     
     HKEY_CURRENT_USERSoftwareKAZAALocalContent
     HKEY_CURRENT_USERSoftwareKAZAALocalContent
     
   • The following values:
     
     adult_filter_level 0x00000000
     bogus_filter 0x00000000
     fiwewall_fileter 0x00000000
     virus_filter 0x00000000
     
     in these registry keys:
     
     HKEY_CURRENT_USERSoftwareKAZAAResultsFilter
     HKEY_USERS.DEFAULTSoftwareKAZAAResultsFilter
     
   • Quarantine %Windows%\%StartupPath%
     
     in these registry keys:
     
     HKEY_CURRENT_USERSoftwareKAZAASettings
     HKEY_USERS.DEFAULTSoftwareKAZAASettings
     
     
8. Creates the following files:
   • C:Autostart.bat
   • C:Ntwrk32.dll
     
     NOTE: These files are not malicious, and thus Symantec antivirus products do not detect them as such. You should manually delete them if found.
     
     
9. Attempts to perform a DDoS attack on three specific Web sites.

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. Run a full system scan and delete all the files detected as W32.HLLW.Winur. Manually delete C:Autostart.bat and C:Ntwrk32.dll if they exist.
3. Reverse the changes that the worm made 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 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.

2. 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.HLLW.Winur, click Delete.
4. Using Windows Explorer, look for the files, C:Autostart.bat and C:Ntwrk32.dll. Delete them if found.

3. Reversing the changes made to the registry

CAUTION: 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.

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 key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete the value:
   
   msconfig C:winrunmsconfig.exe
   
   
5. Navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows
   CurrentVersionRunServices
   
   
6. In the right pane, delete the value:
   
   winrun c:winrunmsconfig.exe
   
   
7. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftMessengerServicePolicies
   
   
8. In the right pane, delete the value:
   
   "IMWarning"="(M)Warning: The person who you are talking to is infected with a virus. Send him the removal tool that can be found in C:klez_removal.exe(M)"
   
   
9. If you have KaZaA installed, restore the security settings that you normally use. See step 7 in the "Technical Details" section for a list of modified keys.
   (You may be able to restore many of these settings within the KaZaA program. Refer to your KaZaA documentation for additional information, or contact KaZaA technical support.)
   
   
10. Exit the Registry Editor.