W32.HLLW.GOP.G@mm

SUMMARY

W32.HLLW.GOP.G@mm is a mass-mailing worm that copies itself to the hard drive as %System%WindowsAgent.exe. It also searches the network drives and copies itself to RecycledNotdelw.i.n.v.e.r.y.i.f.y.exe on any mapped drive on which it can find an operating system. Then, W32.HLLW.GOP.G@mm modifies the Win.ini file to run the worm at startup.

Protection

• Virus Definitions (LiveUpdate™ Weekly) January 22, 2003
• Virus Definitions (Intelligent Updater) January 17, 2003

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
• Large Scale E-mailing: Sends itself to all the email recipients found on an infected machine
• Releases Confidential Info: Steals the OICQ passwords

Distribution

• Distribution Level: High
• Subject of Email: One of many Chinese and English subject lines
• Name of Attachment: Varies with double extension
• Size of Attachment: 44,033 bytes
• Shared Drives: Searches for the shared system drives and copies itself to the Recycled folder

TECHNICAL DETAILS

When W32.HLLW.GOP.G@mm is executed, it does the following:

1. Copies itself as %System%WindowsAgent.exe.
   
   NOTE: %System% is a variable. The Trojan 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. Creates the Drocerrbk.sys file, in which it stores stolen passwords.
   
3. Adds the value:
   
   WindowsAgent   %System%WindowsAgent.exe
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
4. Performs its mass-mailing routine. Mostly, the email message it sends will contain a subject and message in Chinese. The attachment will be a .bmp, .rtf, .doc, .txt, .gif, .jpeg, or .jpg file, which is taken from your computer.
   
   To the original file name, the worm adds a second file extension, either .exe or .lnk. For example, if the original file name is Birthday pic.bmp, the name of the attachment will be Birthday pic.bmp.exe or Birthday pic.bmp.lnk.
   
   The worm searches for email addresses in .htm and .html files, and in many different email mailbox files. After gathering all the email addresses the worm can find, it uses its own SMTP engine to send an email message that can be executed (on unpatched systems) when it is read by the recipient.
   
   NOTE: The worm takes advantage of the IFRAME vulnerability that allows Microsoft Outlook to automatically execute attachments. Information on this vulnerability can be found at: http://www.microsoft.com/windows/ie/downloads/critical/q290108/default.asp.
   
5. Searches the network drives and copies itself to RecycledNotdelw.i.n.v.e.r.y.i.f.y.exe on any mapped drive on which it can find an operating system. Then, the worm sets that particular file to run at startup, by modifying the Win.ini file.

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.GOP.G@mm.
   Delete the Drocerrbk.sys file.
3. Delete the value:
   
   WindowsAgent   %System%WindowsAgent.exe
   
   from the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   

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 the 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), in the "Protection" section, at the top of this writeup.
• 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), in the "Protection" section, at the top of this writeup.
  
  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.GOP.G@mm, click Delete.
4. Follow the instructions for your operating system:
   • Windows 95/98/Me/NT/2000
     • Click Start, point to Find or Search, and then click Files or Folders.
     • Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
     • In the "Named" or "Search for..." box, type, or copy and paste, the file name: Drocerrbk.sys.
     • Click Find Now or Search Now.
     • Delete the displayed files.

• Windows XP
  • Click Start, and then click Search.
  • Click All files and folders.
  • In the "All or part of the file name" box, type, or copy and paste, the file name: Drocerrbk.sys.
  • Verify that "Look in" is set to "Local Hard Drives" or to (C:).
  • Click "More advanced options."
  • Check "Search system folders."
  • Check "Search subfolders."
  • Click Search.
  • Delete the displayed files.

3. Deleting the value from 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 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: WindowsAgent.
   
5. Exit the Registry Editor.