W32.Lokkest.A@mm

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Discovered: January 04, 2007
Updated: January 05, 2007 10:56:11 AM
Type: Worm
Systems Affected: Windows

W32.Lokkest.A@mm is a mass-mailing worm that gathers email addresses from the compromised computer.

Antivirus Protection Dates

  • Initial Rapid Release version January 05, 2007
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version January 05, 2007
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date January 10, 2007

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

Writeup By: Kaoru Hayashi

Discovered: January 04, 2007
Updated: January 05, 2007 10:56:11 AM
Type: Worm
Systems Affected: Windows

W32.Lokkest.A@mm is a mass-mailing worm that gathers email addresses from the compromised computer.

Once executed, the worm creates the following file:
%System%\dllcache\mutex.exe

The worm creates the following registry subkeys:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_WINDOWS_MUTEX_OBJECT
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Windows Mutex Object
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_WINDOWS_MUTEX_OBJECT
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Windows Mutex Object

The worm then modifies the following registry entries to prevent NULL session enumeration of the host and to disable DCOM:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\"restrictanonymous" = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole\"EnableDCOM" = "N"

The worm also modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\"lmcompatibilitylevel" = "1"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\"Start" = "4"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wuauserv\"Start" = "4"

The worm modifies the following registry entry to bypass the Windows Firewall:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List\"%System%\dllcache\mutex.exe" = "%System%\dllcache\mutex.exe:*:Enabled:Windows Mutex Object"

The worm creates a service with the following characteristics:
Service Name: Windows Mutex Object

Next, the worm gathers email addresses from files with the following extensions:
.jsp
.php
.txt
.asp
.shtm
.htm

The worm uses its own SMTP engine to send a copy of itself to the gathered email addresses. The email has the following characteristics:

Subject:
One of the following:
hey remember me?
You have 1 day left
Re: Details
Your IP was logged
Re: Thank you

Message body:
One of the following:
just look it
Details are in the attached document. You need Microsoft Office to open it.
Information about you
Something about you
Take it, and mail me back to tell what you think about it!

Attachment:
One of the following with .scr extension:
picture2393.jpg
maildocument.doc
document.doc
log.txt
my_picture.jpg
picture_pack.rar
maildocument.rar
document.rar
logfile.rar
zipfile.rar

The worm spreads through Yahoo! Messenger, AOL Instant Messenger, MSN Messenger and ICQ.

The worm also spreads to SQL server and network shares protected by weak passwords, and by exploiting the following vulnerabilities:
Symantec Client Security and Symantec AntiVirus Elevation of Privilege (BID 18107)
The RealVNC Remote Authentication Bypass Vulnerability (BID 17978)
The Microsoft Windows Server Service Remote Buffer Overflow Vulnerability (BID 19409)
The Microsoft ASN.1 Library Multiple Stack-Based Buffer Overflow Vulnerabilities (BID 9743)

The worm attempts to stop the following services:
Panda Antivirus
Norton AntiVirus Auto Protect Service
Mcshield

The worm closes windows that contain the following strings:
Ad-aware
spyware
hijack
kav
norton
mcafee
f-pro
lockdown
firewall
blackice
avg
vsmon
zonea
spybot
nod32
reged
avp
troja
viru
anti

The worm attempts to connect to the IRC server link.hottest.es and start an IRC bot. This allows a remote attacker to have unauthorized access to the compromised computer and perform the following actions:
Log keystrokes
Sniff packets
Download and execute files
Act as a proxy server
Steal MSN Messenger password

The worm attempts to modify the TCPIP.SYS driver on Windows XP SP2 in the following folders:
%System%\drivers\TCPIP.SYS
%System%\dllcache\TCPIP.SYS
%Windir%\ServicePackFiles\i386\TCPIP.SYS

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: January 04, 2007
Updated: January 05, 2007 10:56:11 AM
Type: Worm
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.
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. To determine whether definitions for this threat are available by the Intelligent Updater, refer to Virus Definitions (Intelligent Updater).

    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.
  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 subkeys:

    HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_WINDOWS_MUTEX_OBJECT
    HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Windows Mutex Object
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_WINDOWS_MUTEX_OBJECT
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Windows Mutex Object

  5. Navigate to the subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List\

  6. In the right pane, delete the value:

    "%System%\dllcache\mutex.exe" = "%System%\dllcache\mutex.exe:*:Enabled:Windows Mutex Object"

  7. Navigate to the following subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

  8. In the right page, restore the following entry to its previous setting:

    "restrictanonymous" = "1"

  9. Navigate to the following subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole

  10. In the right page, restore the following entry to its previous setting:

    "EnableDCOM" = "N"

  11. Navigate to the following subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

  12. In the right page, restore the following entry to its previous setting:

    "lmcompatibilitylevel" = "1"

  13. Navigate to the following subkeys:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wuauserv

  14. In the right page, restore the following entry to its previous setting:

    "Start" = "4"

  15. Exit the Registry Editor.

Writeup By: Kaoru Hayashi