W32.HLLP.Emesix

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Discovered: March 18, 2003
Updated: February 13, 2007 11:44:34 AM
Type: Virus
Systems Affected: Windows


W32.HLLP.Emesix is a prepended virus that infects the W32 executable files. This virus attempts to quit the programs that have the string "virus"and "Registry Editor." W32.HLLP.Emesix also deletes some system files.

Antivirus Protection Dates

  • Initial Rapid Release version March 18, 2003
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version March 18, 2003
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date March 19, 2003

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

Writeup By: Kaoru Hayashi

Discovered: March 18, 2003
Updated: February 13, 2007 11:44:34 AM
Type: Virus
Systems Affected: Windows


When W32.HLLP.Emesix is executed, it performs the following actions:

  1. Prepends itself to (attaches itself to the beginning of) W32 executable files. It does not infect more than six files in the same folder. W32.HLLP.Emesix also does not infect the files under the System, System32, and Program Files folders.
  2. Drops the file, %Windows%\Explorer6.exe, and adds the value:

    explorer %Windows%\explorer6

    to the registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    NOTE: %Windir% is a variable. The virus locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.
  3. Attempts to quit any program with the string "VIRUS" or "Registry Editor" in its window.
  4. Attempts to delete the following files:
    • C:\Io.sys
    • C:\Autoexec.bat
    • C:\Config.sys
    • C:\Boot.ini


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: Kaoru Hayashi

Discovered: March 18, 2003
Updated: February 13, 2007 11:44:34 AM
Type: Virus
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. Update the virus definitions.
  2. Run a full system scan and delete all the files detected as W32.HLLP.Emesix.
  3. Delete the value that was added to the registry.
  4. Restore the deleted files from a clean backup.
For specific details on each of these steps, 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 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 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.
  2. Run a full system scan.
  3. If any files are detected as infected with W32.HLLP.Emesix, click Delete.

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

    Then click OK. (The Registry Editor opens.)
  3. Navigate to the key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, delete the value: explorer
  5. Exit the Registry Editor.

4. Restoring the deleted files
Recover the following files from a clean backup:
    • C:\Io.sys
    • C:\Autoexec.bat
    • C:\Config.sys
    • C:\Boot.ini
NOTE: Contact your computer vendor for help with restoring the system files, if necessary.

Writeup By: Kaoru Hayashi