W32.Chod@mm

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Discovered: March 13, 2005
Updated: February 13, 2007 12:35:19 PM
Also Known As: Win32.Nochod.{A, S} [Computer Associates], Tobecho.A [Panda Software], W32/NoChod@MM [McAfee], WORM_CHOD.{A, B} [Trend Micro]
Type: Worm
Systems Affected: Windows


W32.Chod@mm is a mass-mailing worm that also propagates using MSN Messenger. The worm has back door capabilities and can be controlled through IRC channels. It also overwrites the Hosts file and lowers security settings.



Removing entries from the Hosts file
If this threat has modified the Windows Hosts file, there are two ways to remove these entries:

  • Install and run the current version of LiveUpdate. This will remove only the entries that refer to Symantec domains.
  • Manually edit the Hosts file and remove all the entries that the worm added.

To run the current version of LiveUpdate
  1. Click download LiveUpdate.

    Note:
    If you are not reading this Web page on the computer that is getting the error notice, the address for downloading the file is:

    ftp://ftp.symantec.com/public/english_us_canada/liveupdate/lusetup.exe

    If necessary, you can type this address into the address bar of the problem computer. Changes to the Hosts file will not stop you from getting to this site.

  2. Save the file to the Windows desktop.
  3. Double-click the lusetup.exe icon on the desktop to install LiveUpdate.
  4. Run LiveUpdate.
  5. Did you see the message "LU1860: LiveUpdate has detected a potential security compromise on your computer"?
    • If you did, let LiveUpdate "Remove these entries from the hosts files" (Recommended).
      This should allow LiveUpdate to run.
    • If you did not, that was not the cause of the problem. Return to the Removal section.


To manually edit the Hosts file and remove all the entries that the worm added

Note: The location of the Hosts file may vary and some computers may not have this file. For example, if the file exists in Windows 98, it will usually be in C:\Windows; and it is located in the C:\WINNT\system32\drivers\etc folder in Windows 2000. There may also be multiple copies of this file in different locations.


Follow the instructions for your operating system:
  • Windows 95/98/Me/NT/2000
    1. Click Start, point to Find or Search, and then click Files or Folders.
    2. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
    3. In the "Named" or "Search for..." box, type:

      hosts

    4. Click Find Now or Search Now.
    5. For each Hosts file that you find, right-click the file, and then click Open With.
    6. Deselect the "Always use this program to open this program" check box.
    7. Scroll through the list of programs and double-click Notepad.
    8. When the file opens, delete all the entries the reference the Web sites listed in Step 10 of the "Technical Details" section.
    9. Close Notepad and save your changes when prompted.

  • Windows XP
    1. Click Start > Search.
    2. Click All files and folders.
    3. In the "All or part of the file name" box, type:

      hosts

    4. Verify that "Look in" is set to "Local Hard Drives" or to (C:).
    5. Click More advanced options.
    6. Check Search system folders.
    7. Check Search subfolders.
    8. Click Search.
    9. Click Find Now or Search Now.
    10. For each Hosts file that you find, right-click the file, and then click Open With.
    11. Deselect the Always use this program to open this program check box.
    12. Scroll through the list of programs and double-click Notepad.
    13. When the file opens, delete all the entries the reference the Web sites listed in Step 10 of the "Technical Details" section.
    14. Close Notepad and save your changes when prompted.


Antivirus Protection Dates

  • Initial Rapid Release version March 14, 2005
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version March 14, 2005
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date March 16, 2005

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

Writeup By: Takayoshi Nakayama

Discovered: March 13, 2005
Updated: February 13, 2007 12:35:19 PM
Also Known As: Win32.Nochod.{A, S} [Computer Associates], Tobecho.A [Panda Software], W32/NoChod@MM [McAfee], WORM_CHOD.{A, B} [Trend Micro]
Type: Worm
Systems Affected: Windows


When W32.Chod@mm is executed, it performs the following actions:

  1. Drops the following files:

    • %System%\cpu.dll
    • %System%\<random folder name>\csrss.dat
    • %System%\<random folder name>\csrss.exe
    • %System%\<random folder name>\csrss.ini

      Note: %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  2. Drops the shortcut C:\Documents and Settings\All Users\Start Menu\Programs\Startup\csrss.lnk.

  3. Adds the value:

    "Csrss" = "%System%\[random folder name]\csrss.exe"

    to the registry keys:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Run

    so that W32.Chod@mm runs every time Windows starts.

  4. Adds the value:

    "Installed" = "1"

    to the registry subkeys:

    HKEY_CLASSES_ROOT\Chode
    HKEY_LOCAL_MACHINE\Software\Classes\Chode
    HKEY_CURRENT_USER\Software\Chode

    as an infection marker.

  5. Adds the values:

    "DisableRegistryTools" = "1"
    "NoAdminPage" = "1"

    to the registry subkey:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
    Policies\System

    to disable registry tools.

  6. Adds the value:

    "DisableSR" = "1"

    to the registry subkey:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\SystemRestore

    to disable system restore.
  7. Adds the values:

    "Hidden" = "2"
    "SuperHidden" = "0"
    "ShowSuperHidden" = "0"

    to the registry subkey:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced

    to hide the dropped file.

  8. Adds the following lines to the win.ini file so that the worm is executed every time Windows starts:

    "Load" = "%System%\csrss.exe"
    "Run" = "%System%\csrss.exe"

  9. Adds the values:

    "Run" = "%System%\[random folder name]\csrss.exe"
    "Load" = "%System%\[random folder name]\csrss.exe"

    to the registry subkey:

    HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows

    so that the worm is executed every time Windows starts.

  10. Deletes the values:

    "MCAgentExe"
    "ISSVC"
    "navapsvc"
    "Symantec"
    "Run\LC"
    "ccEvtMgr"
    "SNDSrvc"
    "ccProxy"
    "ccPwdSvc"
    "ccSetMgr"
    "SPBBCSvc"
    "SAVScan"
    "SBService"
    "SmcService"
    "OutpostFirewal"
    "l"
    "vsmon"
    "CAISafe"
    "net stop"
    "scconfig"
    "CleanUp"
    "MCUpdateExe"
    "VirusScan"
    "Online"
    "VSOCheckTask"
    "ccApp"
    "mcvsrte.exe"
    "Symantec NetDriver Monitor"
    "Outpost"
    "Firewall"
    "gcasServ"
    "KAVPerson"
    "al50"
    "Zone Labs Client"
    "services"
    "microsoftantispyware"
    "hijackthis"

    from the registry subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    to prevent several applications that are associated with the above registry keys from running at system startup.

  11. Modifies the Hosts file to block access to the following Web sites:

    • avp.com
    • ca.com
    • customer.symantec.com
    • dispatch.mcafee.com
    • download.mcafee.com
    • f-secure.com
    • fastclick.net
    • ftp.f-secure.com
    • ftp.sophos.com
    • grisoft.com
    • housecall.trendmicro.com
    • kaspersky.com
    • liveupdate.symantec.com
    • mast.mcafee.com
    • mcafee.com
    • merijn.org
    • my-etrust.com
    • nai.com
    • networkassociates.com
    • pandasoftware.com
    • phpbb.com
    • rads.mcafee.com
    • secure.nai.com
    • securityresponse.symantec.com
    • service1.symantec.com
    • sophos.com
    • spywareinfo.com
    • support.microsoft.com
    • symantec.com
    • trendmicro.com
    • update.symantec.com
    • updates.symantec.com
    • us.mcafee.com
    • vil.nai.com
    • viruslist.com
    • www.avp.com
    • www.awaps.net
    • www.ca.com
    • www.f-secure.com
    • www.fastclick.net
    • www.grisoft.com
    • www.kaspersky.com
    • www.mcafee.com
    • www.merijn.org
    • www.microsoft.com
    • www.my-etrust.com
    • www.nai.com
    • www.networkassociates.com
    • www.pandasoftware.com
    • www.phpbb.com
    • www.sophos.com
    • www.spywareinfo.com
    • www.symantec.com
    • www.trendmicro.com
    • www.viruslist.com
    • www.zonelabs.com
    • www3.ca.com
    • zonelabs.com

  12. Ends the following processes, some of which may be security-related:

    • bbeagle.exe
    • ccapp.exe
    • ccevtmgr.exe
    • ccproxy.exe
    • ccsetmgr.exe
    • d3dupdate.exe
    • enterprise.exe
    • gcasdtserv.exe
    • gcasserv.exe
    • hijackthis.exe
    • i11r54n4.exe
    • irun4.exe
    • isafe.exe
    • issvc.exe
    • kav.exe
    • kavsvc.exe
    • mcagent.exe
    • mcdash.exe
    • mcinfo.exe
    • mcmnhdlr.exe
    • mcshield.exe
    • mcvsescn.exe
    • mcvsftsn.exe
    • mcvsshld.exe
    • mpfagent.exe
    • mpfservice.exe
    • mpftray.exe
    • msblast.exe
    • msconfig.exe
    • mscvb32.exe
    • mskagent.exe
    • mwincfg32.exe
    • navapsvc.exe
    • navapw32.exe
    • navw32.exe
    • npfmntor.exe
    • outpost.exe
    • pandaavengine.exe
    • penis32.exe
    • regedit.exe
    • smc.exe
    • sndsrvc.exe
    • spbbcsvc.exe
    • symlcsvc.exe
    • sysinfo.exe
    • sysmonxp.exe
    • teekids.exe
    • usrprmpt.exe
    • vsmon.exe
    • wincfg32.exe
    • winsys.exe

  13. May attempt to disable the following services:

    • gcasServ
    • hijackthis*
    • KAVPersonal50
    • microsoft antispyware*
    • Outpost Firewall
    • services
    • Symantec NetDriver Monitor
    • Zone Labs Client

  14. Opens a back door to a remote IRC server and allows a remote attacker to have unauthorized access to the compromised computer.

  15. Listens for commands from the attacker to perform some of the following actions:

    • Shut down and reboot the computer
    • Download and execute files
    • Perform ping, TCP, or UDP denial of service attacks
    • Get local host information
    • Spread through MSN messenger
    • Spread via email

  16. Attempts to steal passwords for any of the following applications:

    • AOL Instant Messenger (in old versions)
    • AOL Instant Messenger/Netscape 7
    • GAIM
    • ICQ Lite 4.x/2003
    • Miranda
    • MSN Messenger
    • Trillian
    • Windows Messenger (on Windows XP)
    • Yahoo Messenger (Versions 5.x and 6.x)

  17. Uses one of the following tools to steal passwords from the above application:

    • Intelligent TCPIP.SYS patcher
    • MessenPass
    • Protected Storage PassView

  18. The worm then collects email addresses from files with the following extensions:

    • .adb
    • .asp
    • .cg
    • .ctt
    • .dbx
    • .dhtm
    • .doc
    • .eml
    • .htm
    • .html
    • .msg
    • .oft
    • .php
    • .pl
    • .rtf
    • .sht
    • .shtm
    • .sql
    • .tbb
    • .txt
    • .uin
    • .vbs
    • .wab
    • .xml

      Avoids sending itself to addresses with domain names containing the following strings:

    • antivirus
    • avp
    • bitdefender
    • f-pro
    • f-secure
    • mcafee
    • messagelabs
    • Microsoft
    • spam
    • symantec

  19. Uses its own SMTP engine to send a copy of itself to the email addresses gathered.

    The email has the following characteristics:

    From:
    One of the following:

    • security@microsoft.com
    • security@trendmicro.com
    • securityresponse@symantec.com

      Subject:
      One of the following:

    • Warning - you have been infected!
    • Your computer may have been infected

      Message:

      Your message was undeliverable due to the following reason(s):
      Your message could not be delivered because the destination server was unreachable within the allowed queue period. The amount of time a message is
      queued before it is returned depends on local configuration parameters. Most likely there is a network problem that prevented delivery, but it is also possible
      that the computer is turned off, or does not have a mail system running right now. Your original message has been attached.  

      Attachment:
      One of the following:

    • message.pif
    • message.scr
    • netsky_removal.exe
    • removal_tool.exe

  20. Sends a copy of itself through MSN Messenger. The message has the following characteristics:

    Message:
    One of the following:

    • lol check this out, it freaked me out :S
    • LOL! look at this, I can't explain it in words...
    • omg check this out, it's just wrong :O
    • ROFL!! you have to see this... wtf...
    • you have to see this, it's amazing!
    Attachment:
    One of the following:

    • awesome
    • gross
    • mypic
    • naked lesbian twister
    • paris hilton
    • picture
    • us together

    with one of the following extensions:

    • .exe
    • .scr


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: Takayoshi Nakayama

Discovered: March 13, 2005
Updated: February 13, 2007 12:35:19 PM
Also Known As: Win32.Nochod.{A, S} [Computer Associates], Tobecho.A [Panda Software], W32/NoChod@MM [McAfee], WORM_CHOD.{A, B} [Trend Micro]
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. Restart the computer in Safe Mode.
  3. Delete the values that were added to the registry.
  4. Reinstall your Symantec AntiVirus Product.
  5. Update the virus definitions.
  6. Run a full system scan and delete all the files detected as W32.Chod@mm.
  7. Edit the win.ini file.
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, 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 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.
Note: Step 4 should be completed while in Safe mode.


3. 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. 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 subkeys:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Run

  4. In the right pane, delete the value:

    "Csrss" = "%System%\[random folder name]\csrss.exe"

  5. Navigate to the subkey:

    HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows

  6. In the righ pane, delete the values:

    "Load" = "%System%\[random folder name]\csrss.exe"
    "Run" = "%System%\[random folder name]\csrss.exe"

  7. Navigate to the registry subkeys:

    HKEY_CLASSES_ROOT\Chode
    HKEY_LOCAL_MACHINE\Software\Classes\Chode
    HKEY_CURRENT_USER\Software\Chode

  8. In the right pane, delete the value:

    "Installed" = "1"

  9. Navigate to the registry subkey:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
    Policies\System

  10. In the right pane, delete the values:

    "DisableRegistryTools" = "1"
    "NoAdminPage" = "1"

  11. Navigate to the registry subkey:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
    Explorer\Advanced

  12. In the right pane, delete the values:

    "Hidden" = "2"
    "SuperHidden" = "0"
    "ShowSuperHidden" = "0"

  13. Exit the Registry Editor.

4. To reinstall your Symantec antivirus program
As this virus attempts to remove the files and registry subkeys that your Symantec antivirus program uses, you may need to reinstall the program. If your Symantec antivirus program is not working properly, uninstall, and then reinstall it. For instructions on how to do this, please consult the documentation that came with your Symantec product.

Restart the computer in Normal mode and proceed with section 5.


5. 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 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 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.

    Note: If you see an error, such as LU1418, when you try to run LiveUpdate and you cannot get the Web site hosting the Intelligent Updater, it is likely that the worm has modified the Hosts file. You can either download and install LiveUpdate 2.5, which can remove Symantec entries from that file, or you can edit it yourself. See the instructions for both in the "Additional Information" section below.

6. 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.Chod@mm, click Delete.

    Note:
    If your Symantec antivirus product reports that it cannot delete an infected file, Windows may be using the file. To fix 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 section 4.

7. Edit the Win.ini file
    If you are running Windows 95/98/Me, follow these steps:
    1. Click Start > Run.
    2. Type the following:

      edit c:\windows\win.ini

      and then click OK.

      (The MS-DOS Editor opens.)

      NOTE: If Windows is installed in a different location, make the appropriate path substitution.

    3. In the [windows] section of the file, look for a line similar to:

      "Run" = "%System%\csrss.exe"

    4. If this line exists, delete everything to the right of run=

    5. In the [windows] section of the file, look for a line similar to:

      "Load" = "%System%\csrss.exe"

    6. If the line exists, delete everything to the right of load=

    7. Click File > Save.

    8. Click File > Exit.


Writeup By: Takayoshi Nakayama