Discovered: June 21, 2002
Updated: February 13, 2007 12:00:14 PM
Also Known As: WORM_GUBED.A, W32.Gubed@mm
Systems Affected: Windows
W32.Gubed.int is an intended mass-mailing worm that attempts to send itself to all email addresses that it finds on an infected computer. The subject of the email message is "Congratulations for your site," and the attachment is "WebMakeFullInstall.exe." The worm also drops a script that is an intended mass-mailing worm, but due to bugs in the code, the script does not perform the mass-mailing functionality.
The worm copies itself as \%System%\DebugW32.exe, copies itself five times to both the \Windows and \Windows\System folder, and creates the Start.vbs file in the Startup folder. Start.vbs attempts to overwrite .vbs files that are in the My Documents folder and its subfolders.
Antivirus Protection Dates
- Initial Rapid Release version June 24, 2002
- Latest Rapid Release version September 28, 2010 revision 054
- Initial Daily Certified version June 24, 2002
- Latest Daily Certified version September 28, 2010 revision 036
- Initial Weekly Certified release date June 26, 2002
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
When W32.Gubed.int runs, it does the following:
It searches the following files for email addresses:
It then attempts to send the following email message to all addresses that it finds:
Subject: Congratulations for your site
Congratulations for your site
This is a good tool to improve it.
The worm also drops a script that is a second, intended mass-mailing worm. It attempts to send itself to all email addresses that are in the Microsoft Outlook Address Book, but due to bugs in the code, the worm does not perform the mass-mailing function. If it were successful, the email message would have the following characteristics:
Subject: Important EMail for [recipient's name]
Message: Look at this attached file, it may be important.
W32.Gubed.int then copies itself to \%System%\DebugW32.exe. It then adds the value
to the registry key
so that the file runs when you restart Windows.
The worm also creates \%Windows%\Start Menu\Programs\StartUp\Start.vbs. This VBScript attempts to search the My Documents folder and its subfolders for files that have the .vbs extension. The worm attempts to overwrite each file with Start.vbs, but due to bugs in the code, the script does not perform this action.
Finally, the worm copies itself five times to both the \Windows and the \Windows\System folders. To do this, the worm searches for an .exe file, copies the file name, and appends "_vbpe.exe" to it. For example, if it finds Actmovie.exe, it copies itself to Actmovie.exe_vbpe.exe. It does this for five files in both folders.
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.
Update the virus definitions, run a full system scan, and delete all files that Norton AntiVirus detects as W32.Gubed.int.
- Delete the value
from the registry key
For details on how to do this, read the following instructions.
To scan with Norton AntiVirus and delete the infected files:
- 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.
- Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files.
- NAV Consumer products: Read the document How to configure Norton AntiVirus to scan all files.
- NAV Enterprise products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
- Run a full system scan.
- Delete all files that NAV detects as W32.Gubed.int.
To remove 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 only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
- Click Start, and click Run. The Run dialog box appears.
- Type regedit and then click OK. The Registry Editor opens.
- Navigate to the following key:
- In the right pane, delete the following value:
- Click Registry, and click Exit.
Writeup By: Douglas Knowles