W32.HLLW.Gaobot.P

SUMMARY

W32.HLLW.Gaobot.P is a worm that attempts to spread itself to the network shares. This threat also allows for a hacker to remotely access an infected computer through IRC.

W32.HLLW.Gaobot.P is compressed with UPX.

Protection

• Virus Definitions (LiveUpdate™ Weekly) April 9, 2003
• Virus Definitions (Intelligent Updater) April 4, 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
• Degrades Performance: Contains functionality to copy itself to remote computers, which may cause a network slowdown
• Compromises Security Settings: Allows unauthorized actions on your computer

Distribution

• Distribution Level: Medium
• Ports: Randomly changed
• Shared Drives: Attempts to copy itself to all the network shares

TECHNICAL DETAILS

When W32.HLLW.Gaobot.P runs, it does the following:

1. Copies itself as:
   • %System%Svchosl.exe
   • %System%Winhlpp32.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).
     
     
2. Adds the string value:
   
   "Config Loader"="svchosl.exe"
   
   to these registry keys:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersion
   RunServices
   
   so that the worm runs when you start Windows.
   
3. Creates the registry keys:
   
   HKEY_LOCAL_MACHINESoftwareMSSQLServerClientSuperSocketNetLib
   HKEY_LOCAL_MACHINESoftwareMicrosoftClientSuperSocketNetLib
   
   and adds this string value to the keys:
   
   "ProtocolOrder"="tcp"
   
4. Creates the registry keys:
   
   HKEY_LOCAL_MACHINESoftwareMSSQLServerClientConnectTo
   HKEY_LOCAL_MACHINESoftwareMicrosoftMSSQLServerClientConnectTo
   
   and adds this string value to the key:
   
   "DSQUERY"="DBNETLIB"
   
5. Drops the file, %System%Psexec.exe, which is 122,880 bytes in length. This is the Sysinternals remote execution utility.
   
6. Adds itself as a service with the name, "PSINFSVC" or "PsInfo Servic."
   
7. Opens a randomly changed TCP port to connect to the hacker.
   
8. Contains its own IRC client, allowing it to connect to an IRC channel that the worm predefines. Using the IRC channel, the worm listens for the commands from the hacker, who may perform any of the following actions:
   • Manages the installation of the worm
   • Dynamically updates the installed worm
   • Downloads and executes the files, which the hacker selects
   • Steals the compromised system information
   • Steals the CD-keys of some electronic games
   • Sends the worm to other IRC users
   • Launches flooding attacks
   • Opens/Closes the CD-ROM drive
   • Scans for and attempts to log in to the Microsoft SQL Servers
     
     
9. Probes the IPC$ shares using trivial user/password combinations. The worm uses Psexec.exe to copy itself as %Windir%System32Winhlpp32.exe to the shares and executes this copy in the remote computers. This action will only succeed if an open IPC$ exists.
   
   NOTE: %Windir% is a variable. The worm locates the Windows installation folder of the remote system and copies itself to the folder system32 under this location. By default, %Windir% is C:Windows or C:Winnt.
   
10. Creates a named Pipe \.pipepsexecsvc and redirects the information from the pipe to the command psexec.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

The following 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.Gaobot.P.
3. Restart the computer in Safe mode.
4. Reverse the changes made to the registry.
   

For specific details on each of these steps, 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 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. 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.Gaobot.P, click Delete.

3. Restarting the computer in Safe mode
All the Windows 32-bit operating systems, except Windows NT, can be restarted in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."


4. Reversing the changes made to the registry


CAUTION: Symantec strongly recommends backing 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 each of the keys:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersion
   RunServices
   
4. In the right pane, delete this value:
   
   "Config Loader"="svchosl.exe"
   
5. Navigate to these keys and delete them:
   
   HKEY_LOCAL_MACHINESoftwareMSSQLServerClient
   HKEY_LOCAL_MACHINESoftwareMicrosoftClient
   HKEY_LOCAL_MACHINESoftwareMicrosoftMSSQLServerClientConnectTo
   
6. Exit the Registry Editor.