W32.Chod.D

1. Copies itself as the following:
   
   %System%\[RANDOM FOLDER NAME]\csrss.exe
   
   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 following files:
   
   
   • %System%\[RANDOM FOLDER NAME]\csrss.dat
   • %System%\[RANDOM FOLDER NAME]\csrss.ini
     
     
3. Creates the following shortcut to itself so that it executes every time Windows starts:
   
   %UserProfile%\Start Menu\Programs\Startup\csrss.lnk
   
   Note: %UserProfile% is a variable that refers to the current user's profile folder. By default, this is C:\Documents and Settings\[CURRENT USER] (Windows NT/2000/XP).
   
   
4. Adds the values:
   
   "Hidden" = "2"
   "SuperHidden" = "0"
   "ShowSuperHidden" = "0"
   
   to the registry subkey:
   
   HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
   Explorer\Advanced
   
   so that Windows Explorer will not show Hidden and System files.
   
   
5. Adds the values:
   
   "DisableRegistryTools" = "1"
   "NoAdminPage" = "1"
   
   to the registry subkey:
   
   HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
   Policies\System
   
   to disable the Registry Editor on the Remote administration tab in the Password Properties dialog box.
   
   
6. Adds the value:
   
   "Installed" = "1"
   
   to the registry subkeys:
   
   HKEY_CURRENT_USER\Software\Chode
   HKEY_CLASSES_ROOT\Chode
   
   
7. Adds the value:
   
   "csrss" = ""
   
   to the registry subkeys:
   
   HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   
8. Adds the following lines to the file %Windir%\win.ini on computers running Windows 95/98/ME:
   
   run = %System%\[RANDOM FOLDER NAME]\csrss.exe
   load = %System%\[RANDOM FOLDER NAME]\csrss.exe
   
   Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.
   
   
9. Adds the values:
   
   "Load" = "%System%\[RANDOM FOLDER NAME]\csrss.exe"
   "Run" = "%System%\[RANDOM FOLDER NAME]\csrss.exe"
   
   to the registry subkey:
   
   HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
   
   
10. Stops the following security-related services:
    
    
    • ccEvtMgr
    • SNDSrvc
    • ccProxy
    • ccPwdSvc
    • ccSetMgr
    • SPBBCSvc
    • SAVScan
    • SBService
    • SmcService
    • OutpostFirewall
    • vsmon
    • CAISafe
    • PcCtlCom
    • TmPfw
      
      
11. Attempts to disable the Windows Firewall and the Windows Security Center.
    
    
12. Ends the following processes, which may be related to other threats or security-related programs:
    
    
    • msconfig.exe
    • kav.exe
    • kavsvc.exe
    • mcvsshld.exe
    • mcagent.exe
    • mcvsrte.exe
    • mcshield.exe
    • mcvsftsn.exe
    • mcdash.exe
    • mcvsescn.exe
    • mcinfo.exe
    • mpfagent.exe
    • mpftray.exe
    • mpfservice.exe
    • mskagent.exe
    • mcmnhdlr.exe
    • sndsrvc.exe
    • usrprmpt.exe
    • ccapp.exe
    • ccevtmgr.exe
    • spbbcsvc.exe
    • ccsetmgr.exe
    • symlcsvc.exe
    • npfmntor.exe
    • navapsvc.exe
    • issvc.exe
    • ccproxy.exe
    • navapw32.exe
    • navw32.exe
    • smc.exe
    • outpost.exe
    • zlclient.exe
    • vsmon.exe
    • isafe.exe
    • pandaavengine.exe
    • msblast.exe
    • penis32.exe
    • teekids.exe
    • bbeagle.exe
    • d3dupdate.exe
    • sysmonxp.exe
    • i11r54n4.exe
    • irun4.exe
    • mscvb32.exe
    • sysinfo.exe
    • mwincfg32.exe
    • wincfg32.exe
    • winsys.exe
    • zapro.exe
    • winupd.exe
    • enterprise.exe
    • regedit.exe
    • hijackthis.exe
    • gcasdtserv.exe
    • gcasserv.exe
    • pcctlcom.exe
    • tmntsrv.exe
    • tmproxy.exe
    • pccguide.exe
    • tmpfw.exe
    • pcclient.exe
      
      
13. Attempts to delete entries from the following registry subkeys to disable several security-related programs:
    
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\CleanUp
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\MCAgentExe
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\MCUpdateExe
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\VirusScan
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Online
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\VSOCheckTask
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\ccApp
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Symantec
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\NetDriver
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Monitor
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\SmcService
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Outpost
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Firewall
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\gcasServ
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\pccguide.exe
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\KAVPersonal50
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Zone Labs Client
    
    
14. Adds the following lines to the hosts file to prevent access to various security-related Web sites:
    
    127.0.0.1 avp.com
    127.0.0.1 www.avp.com
    127.0.0.1 ca.com
    127.0.0.1 dispatch.mcafee.com
    127.0.0.1 download.mcafee.com
    127.0.0.1 f-secure.com
    127.0.0.1 fastclick.net
    127.0.0.1 ftp.f-secure.com
    127.0.0.1 ftp.sophos.com
    127.0.0.1 liveupdate.symantec.com
    127.0.0.1 customer.symantec.com
    127.0.0.1 rads.mcafee.com
    127.0.0.1 mast.mcafee.com
    127.0.0.1 mcafee.com
    127.0.0.1 my-etrust.com
    127.0.0.1 nai.com
    127.0.0.1 networkassociates.com
    127.0.0.1 secure.nai.com
    127.0.0.1 securityresponse.symantec.com
    127.0.0.1 service1.symantec.com
    127.0.0.1 sophos.com
    127.0.0.1 support.microsoft.com
    127.0.0.1 symantec.com
    127.0.0.1 update.symantec.com
    127.0.0.1 updates.symantec.com
    127.0.0.1 us.mcafee.com
    127.0.0.1 vil.nai.com
    127.0.0.1 viruslist.com
    127.0.0.1 www.viruslist.com
    127.0.0.1 www.awaps.net
    127.0.0.1 www.ca.com
    127.0.0.1 www.f-secure.com
    127.0.0.1 www.fastclick.net
    127.0.0.1 www.mcafee.com
    127.0.0.1 www.microsoft.com
    127.0.0.1 www.my-etrust.com
    127.0.0.1 www.nai.com
    127.0.0.1 www.networkassociates.com
    127.0.0.1 www.sophos.com
    127.0.0.1 www.symantec.com
    127.0.0.1 www3.ca.com
    127.0.0.1 www.grisoft.com
    127.0.0.1 grisoft.com
    127.0.0.1 housecall.trendmicro.com
    127.0.0.1 trendmicro.com
    127.0.0.1 www.trendmicro.com
    127.0.0.1 www.pandasoftware.com
    127.0.0.1 pandasoftware.com
    127.0.0.1 kaspersky.com
    127.0.0.1 www.kaspersky.com
    127.0.0.1 www.zonelabs.com
    127.0.0.1 zonelabs.com
    127.0.0.1 www.spywareinfo.com
    127.0.0.1 spywareinfo.com
    127.0.0.1 www.merijn.org
    127.0.0.1 merijn.org
    
    
15. Opens a back door on the compromised computer by connecting to an IRC channel on one of the following domains:
    
    
    • [http://]update.ch0de.info/[REMOVED]
    • [http://]bk.vbulettin.com/[REMOVED]
    • [http://]bk.ch0dewaffles.info/[REMOVED]
    • [http://]superaids.zapto.org/[REMOVED]
      
      
16. Allows a remote attacker to perform the following actions on the compromised computer:
    
    
    • Run a shell command
    • End processes
    • Download and delete files
    • Install an IRC daemon
    • Download updates to the worm
    • Spread through MSN Messenger
    • Patch the system driver TCPIP.SYS to allow many simultaneous connections
    • Shutdown and restart the compromised computer
    • Run a hacktool
    • Steal passwords
    • Perform denial of service attacks
      
      
17. Spreads through MSN Messenger by sending the following message to all MSN contacts gathered from the compromised computer:
    
    hey, is this you?
    [http://]www.vbulettin.com/[REMOVED]msn.php?email=[RANDOM EMAIL ADDRESS]  
    
    Note: If a recipient clicks on the above link a copy of the worm will be downloaded onto the recipient's computer.
    

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.