W32.Korgo.U

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Discovered: June 22, 2004
Updated: February 13, 2007 12:24:31 PM
Also Known As: Worm.Win32.Padobot.l [Kaspersk, W32/Korgo.worm.u [McAfee], WORM_KORGO.U [Trend], Win32.Korgo.W [Computer Associ, W32/Korgo-Fam [Sophos]
Type: Worm
Systems Affected: Windows



W32.Korgo.U is a variant of W32.Korgo.N . This worm attempts to propagate by exploiting the Microsoft Windows LSASS Buffer Overrun Vulnerability (described in Microsoft Security Bulletin MS04-011 ) on TCP port 445. It also listens on TCP ports 113, 5111, and a random port between 256 and 8191.

Notes:

  • Definitions dated prior to June 28, 2004 detect this threat as W32.Korgo.O.
  • Symantec Security Response has developed a removal tool to clean the infections of W32.Korgo.U.


Antivirus Protection Dates

  • Initial Rapid Release version June 22, 2004
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version June 22, 2004
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date June 23, 2004

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

Discovered: June 22, 2004
Updated: February 13, 2007 12:24:31 PM
Also Known As: Worm.Win32.Padobot.l [Kaspersk, W32/Korgo.worm.u [McAfee], WORM_KORGO.U [Trend], Win32.Korgo.W [Computer Associ, W32/Korgo-Fam [Sophos]
Type: Worm
Systems Affected: Windows


When W32.Korgo.U is executed, it performs the following actions:

  1. Deletes the file, ftpupd.exe, from the folder in which the worm was executed.

  2. Creates the following mutexes to ensure that only one instance of the worm is executed on the computer:
    • u8
    • u9
    • u10
    • u11
    • u12
    • u13
    • u14
    • uterm14

  3. Creates the event object "u13x."

  4. Opens the following event objects:
    • u10x
    • u11x
    • u12x

  5. Deletes the values:

    "Windows Security Manager"
    "Disk Defragmenter"
    "System Restore Service"
    "Bot Loader"
    "SysTray"
    "WinUpdate"
    "Windows Update Service"
    "avserve.exe"
    "avserve2.exeUpdate Service"
    "MS Config v13"

    from the registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

  6. Copies itself as %System%\<random filename>.exe.


    Note:
    %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  7. Adds the values:

    "Client"="1"
    "ID"="<random value>"

    to the registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Wireless

  8. Adds the value:

    "Windows Update"="%System%\<random filename>.exe"

    to the registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

  9. Attempts to inject a function into Explorer.exe as a thread.

    If successful, this threat will continue to run in the Explorer.exe process. All the actions described in the next step will appear to be done by Explorer.exe, and the worm will not show when viewing the process list in the Windows Task Manager.

    If unsuccessful, the worm will continue to run as its own process.

  10. Creates additional threads and does the following:


    Note: While the worm creates these threads, it prevents the computer from shutting down or restarting.

    • Opens TCP ports 113, 5111, and a random port between 256 and 8191, which the worm uses to send itself.

    • Attempts to connect and update itself from one of the following HTTP servers:
      • adult-empire.com
      • asechka.r
      • citi-bank.ru
      • color-bank.ru
      • crutop.nu
      • cvv.ru
      • fethard.biz
      • filesearch.ru
      • fuck.ru
      • goldensand.ru
      • hackers.lv
      • kavkaz.ru
      • kidos-bank.ru
      • konfiskat.org
      • lovingod.host.sk
      • master-x.com
      • mazafaka.ru
      • padonki.org
      • parex-bank.ru
      • trojan.ru
      • www.redline.ru
      • xware.cjb.net

    • Attempts to exploit the LSASS Windows vulnerability on TCP port 445 (described in Microsoft Security Bulletin MS04-011), against random IP addresses. If the worm successfully finds a vulnerable computer, the computer will attempt to reconnect to the infected computer to download 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.

Discovered: June 22, 2004
Updated: February 13, 2007 12:24:31 PM
Also Known As: Worm.Win32.Padobot.l [Kaspersk, W32/Korgo.worm.u [McAfee], WORM_KORGO.U [Trend], Win32.Korgo.W [Computer Associ, W32/Korgo-Fam [Sophos]
Type: Worm
Systems Affected: Windows


Before you begin :
If you are running Windows 2000 or XP, and have not yet done so, you must patch for the vulnerability described in Microsoft Security Bulletin MS04-011 . If you do not, it is likely that your computer will continue to be re-infected.

Removal using the W32.Korgo Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Korgo.U. Use this removal tool first, as it is the easiest way to remove this threat.

Manual Removal
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. Restart the computer in Safe mode or VGA mode.
  4. Run a full system scan and delete all the files detected as W32.Korgo.U.
  5. Reverse the changes made to the registry.
For 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, re-enable 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: 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.

3. To restart the computer in Safe mode or VGA mode

Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.
  • For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
  • For Windows NT 4 users, restart the computer in VGA mode.
4. To scan for and delete the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with W32.Korgo.U, click Delete.

5. To reverse the changes made to the registry


WARNING: 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 > Run.
  2. Type regedit

    Then click OK.

  3. Navigate to the key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

  4. In the right pane, delete the value:

    "Windows Update"="%System%\<random filename>.exe"

  5. Navigate to the key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Wireless

  6. In the right pane, delete the values:

    "Client"="1" and
    "ID" = "<random value>"

  7. Exit the Registry Editor.

  8. Restart the computer in Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."