Discovered: November 07, 2008
Updated: November 07, 2008 5:16:59 PM
Also Known As: W32/AutoRun-XE [Sophos]
Type: Worm
Infection Length: 281,551 bytes
Systems Affected: Windows

W32.Gaut.A is a worm that spreads through shared, local, and removable drives. It may also spread through certain instant messaging applications.

Antivirus Protection Dates

  • Initial Rapid Release version November 07, 2008 revision 016
  • Latest Rapid Release version February 19, 2013 revision 016
  • Initial Daily Certified version November 07, 2008 revision 024
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date November 12, 2008

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Stephen Doherty

Discovered: November 07, 2008
Updated: November 07, 2008 5:16:59 PM
Also Known As: W32/AutoRun-XE [Sophos]
Type: Worm
Infection Length: 281,551 bytes
Systems Affected: Windows

When the worm executes, it creates the following files:

  • %SystemDrive%\autorun.ini
  • %SystemDrive%\chrome.exe
  • %Windows%\chrome.exe


The worm also creates the following file and increments it from the previous value:
C:\WINDOWS\Tasks\At1.job

Next, the worm creates the following registry entry so that it executes whenever Windows starts:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"Yahoo Messengger" = "C:\WINDOWS\system32\chrome.exe"

It then modifies the following registry entry so that it executes whenever Windows starts:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Shell" = "Explorer.exe chrome.exe"

The worm then creates the following registry entries:
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WorkgroupCrawler\Shares\"shared" = "\New Folder.exe"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NofolderOptions" = "1"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\"DisableTaskMgr" = "1"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\"DisableRegistryTools" = "1"


Next, it modifies the following registry entries:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\"Default_Page_URL" = "http://h1.ripway.com/poojasharma2/index.html"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\"Default_Search_URL" = "http://h1.ripway.com/poojasharma2/index.html"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\"Search Page" = "http://h1.ripway.com/poojasharma2/index.html"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\"Start Page" = "http://h1.ripway.com/poojasharma2/index.html"
  • HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\"Start Page" = "http://h1.ripway.com/poojasharma2/index.html"


The worm modifies the following registry entry by incrementing it from its previous value:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Schedule\"NextAtJobId" = "2"

Next, the worm downloads a configuration file from the following location:
[http://]h1.ripway.com

It stores the file in the following location:
%SystemDrive%\setting.ini

If the above file already exists, it copies it to the following location:
%SystemDrive%\setting.ini.old

This file is used to configure the following information:
  • Spam messages sent
  • Registry modifications
  • Update URLs for the worm


Next, the worm attempts to copy itself to all local and removable drives, except the A drive, as the following files:
%DriveLetter%\New Folder.exe

It also creates the following file so that it is executed whenever the drive is accessed:
%DriveLetter%\autorun.inf

The worm also creates the following file so that only one instance of the worm exists on the computer:
C:\disk.txt

It may also enumerate and copy itself to shared folders as the following file:
[SHARED FOLDER]\New Folder.exe

The worm then ends the following process:
game_y.exe

It also closes any windows with the following names:
  • Bkav2006
  • System Configuration
  • Registry
  • Windows Task
  • [FireLion]
  • cmd.exe


The worm searches for open applications with the following names:
  • Google Talk
  • Yahoo! Messenger


It then sends one of the following spam messages to all contacts in the application:
  • Now search your google in a HYBRID\DYNAMIC way...
  • Hey what are you doing Please test my new webcam using private application...
  • The wisest mind has something yet to learn...
  • Hey Please help me to test my new cam application...
  • ok
  • thats fine
  • Waiting for you, view my private cam via secured connection...
  • Happiness is not a destination. It is a method of life...
  • View my private cam via secured connection...
  • If you want truly to understand something, try to change it...
  • asl please
  • I am 23 Female, Delhi (India)
  • and you?


The spammed message also contains a link to the worm.

Recommendations

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.

Writeup By: Stephen Doherty

Discovered: November 07, 2008
Updated: November 07, 2008 5:16:59 PM
Also Known As: W32/AutoRun-XE [Sophos]
Type: Worm
Infection Length: 281,551 bytes
Systems Affected: Windows

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Disable System Restore (Windows Me/XP).
  2. Update the virus definitions.
  3. Run a full system scan.
  4. Delete any values added to the registry.
  5. Extract and restore Windows files.
  6. Restore the default settings in Internet Explorer.
  7. Reset the Internet Explorer home page.

For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable System Restore by following the instructions in the aforementioned documents.

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article: Antivirus Tools Cannot Clean Infected Files in the _Restore Folder (Article ID: Q263455).

2. To update 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.

    If you use Norton AntiVirus 2006, Symantec AntiVirus Corporate Edition 10.0, or newer products, LiveUpdate definitions are updated daily. These products include newer technology.

    If you use Norton AntiVirus 2005, Symantec AntiVirus Corporate Edition 9.0, or earlier products, LiveUpdate definitions are updated weekly. The exception is major outbreaks, when definitions are updated more often.


  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted daily. You should download the definitions from the Symantec Security Response Web site and manually install them.

The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions . For detailed instructions read the document: How to update virus definition files using the Intelligent Updater .

3. To run a full system scan
  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, follow the instructions displayed by your antivirus program.
Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do this, run the scan in Safe mode. For instructions, read the document, How to start the computer in Safe Mode . Once you have restarted in Safe mode, run the scan again.
After the files are deleted, restart the computer in Normal mode and proceed with the next section.

Warning messages may be displayed when the computer is restarted, since the threat may not be fully removed at this point. You can ignore these messages and click OK. These messages will not appear when the computer is restarted after the removal instructions have been fully completed. The messages displayed may be similar to the following:

Title: [FILE PATH]
Message body: Windows cannot find [FILE NAME]. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.

4. To delete the value from the registry
Important: 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 subkeys only. For instructions refer to the document: How to make a backup of the Windows registry .
  1. Click Start > Run.
  2. Type regedit
  3. Click OK.

    Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.

  4. Navigate to and delete the following registry entries:

    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"Yahoo Messengger" = "C:\WINDOWS\system32\chrome.exe"
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WorkgroupCrawler\Shares\"shared" = "\New Folder.exe"
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NofolderOptions" = "1"
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\"DisableTaskMgr" = "1"
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\"DisableRegistryTools" = "1"

  5. Restore the following registry entries to their previous values, if required:

    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Shell" = "Explorer.exe chrome.exe"
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\"Default_Page_URL" = "http://h1.ripway.com/poojasharma2/index.html"
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\"Default_Search_URL" = "http://h1.ripway.com/poojasharma2/index.html"
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\"Search Page" = "http://h1.ripway.com/poojasharma2/index.html"
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\"Start Page" = "http://h1.ripway.com/poojasharma2/index.html"
    • HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\"Start Page" = "http://h1.ripway.com/poojasharma2/index.html"
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Schedule\"NextAtJobId" = "2"

  6. Exit the Registry Editor.

    Note: If the risk creates or modifies registry subkeys or entries under HKEY_CURRENT_USER, it is possible that it created them for every user on the compromised computer. To ensure that all registry subkeys or entries are removed or restored, log on using each user account and check for any HKEY_CURRENT_USER items listed above.
5. To extract and restore Windows files
The following documents provide general instructions on how to extract files. This information is provided for your convenience. The exact steps may vary slightly depending on the configuration of your operation system, the location of the files, and so on. For additional information, read the Help files, contact Microsoft, or refer to the following Windows documentation:
6. To restore the default settings in Internet Explorer
  1. Click Start > Settings > Control Panel
  2. Select Internet Options
  3. Select the Programs tab
  4. Click Reset Web Settings
  5. Click OK
  6. Exit the Control Panel
7. To reset the Internet Explorer home page
  1. Start Microsoft Internet Explorer.
  2. Connect to the Internet, and then go to the page that you want to set as your home page.
  3. Click Tools > Internet Options.
  4. In the Home page section of the General tab, click Use Current > OK.
For additional information, or if this procedure does not work, read the Microsoft Knowledge Base article: Home Page Setting Changes Unexpectedly, or You Cannot Change Your Home Page Setting , Article ID 320159.

Writeup By: Stephen Doherty