1. Symantec/
  2. Security Response/
  3. W32.Navidad

W32.Navidad

Risk Level 2: Low

Discovered:
November 3, 2000
Updated:
February 13, 2007 11:57:49 AM
Also Known As:
I-Worm.Navidad.a [Kaspersky], W32/Navidad.gen@M [McAfee], Win32.Navidad [Computer Associ, W32/Navidad [Sophos], WORM_NAVIDAD.A [Trend]
Type:
Worm
Systems Affected:
Windows

NOTE: If you are running Windows 95 or Windows 98, it is assumed that Windows is located in C:\Windows. If you are running Windows NT or Windows 2000, it is assumed that Windows is located in C:\Winnt. If Windows is installed in a different directory, make the appropriate substitutions.

This is how the worm works:
  1. When executed, the worm displays a dialog box with the cryptic letters

    UI

    and the title

    Error
  2. If you are running Windows 95 or Windows 98, the worm adds the following registry key:

    HKEY_USERS\.DEFAULT\Software\Navidad

    If you are running Windows NT or Windows 2000, the worm adds the following registry key:

    HKEY_CURRENT_USER\Software\Navidad

    This key was supposed to be used to see if the computer was already infected. However, due to bugs in the code, the registry key is not used.
  3. If you are running Windows 95 or Windows 98, the worm adds the following registry key:

    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    with the value

    Win32BaseServiceMOD=\Windows\System\Winsvrc.exe

    If you are running Windows NT or Windows 2000, the worm adds the following registry key:

    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    with the value

    Win32BaseServiceMOD=\Winnt\System32\Winsvrc.exe
  4. The worm copies itself into the Windows system folder as Winsvrc.vxd. Due to the difference in file name, the virus does not execute properly at startup. After the file has been copied, the worm modifies two additional registry keys. If you are running Windows 95 or Windows 98, the worm changes

    HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\exefile\shell\open\command
    HKEY_CLASSES_ROOT\exefile\shell\open\command

    to equal

    \Windows\System\winsvrc.exe "%1" %*"

    If you are running Windows NT or Windows 2000, the worm changes

    HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\exefile\shell\open\command
    HKEY_CLASSES_ROOT\exefile\shell\open\command

    to equal

    \Winnt\System32\winsvrc.exe "%1" %*"

    Due to the mistake in the file name, the system is unusable. Whenever an .exe file is executed, the Windows prompts you for the location of Winsvrc.exe. The net result is that no program files can be launched. This may cause system instability and you may have difficulty restarting the system.
  5. Next, the worm begins the email routine. The worm uses MAPI to send mail and works with any MAPI-compliant email client, including Microsoft Outlook. The worm checks for all messages in your Inbox and replies to those messages that have one attachment. The reply consists of the same subject line and body, but contains the worm attached as NAVIDAD.EXE.
  6. Finally, the worm places a blue eye icon in the system tray of the taskbar. When the mouse pointer is over the icon, the worm displays a yellow dialog box that states

    Lo estamos mirando... (In English: We are watching it...)

    When you click the icon, a dialog box with a button appears. The button contains the following text:

    Nunca presionar este boton (In English: Never press this button)

    If you click the button, an error box with the title

    Feliz Navidad (In English: Merry Christmas)

    displays the message

    Lamentablemente cayo en la tentacion y perdio su computadora (In English: Unfortunately you've fallen to temptation and have lost your computer)

    If you close the dialog box by clicking the X instead of clicking the button, the following message appears:

    buena eleccion (In English: Good selection)

    and exits. Despite the warning of losing the computer, no further changes are made to the system.


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: Eric Chien
Summary| Technical Details| Removal

Search Threats

Search by name
Example: W32.Beagle.AG@mm
STAR Antimalware Protection Technologies
2016 Internet Security Threat Report, Volume 21
  • Twitter
  • Facebook
  • LinkedIn
  • Google+
  • YouTube