W32.Korron.B

When the worm executes, it may create the following files:

• %UserProfile%\Local Settings\Application Data\WINDOWS\CSRSS.EXE
• %UserProfile%\Local Settings\Application Data\WINDOWS\LSASS.EXE
• %UserProfile%\Local Settings\Application Data\WINDOWS\SERVICES.EXE
• %UserProfile%\Local Settings\Application Data\WINDOWS\SMSS.EXE
• %UserProfile%\Local Settings\Application Data\WINDOWS\WINLOGON.EXE
• %System%\Coollman.scr
• %System%\Driver\Printer\LX300\Ac.ico
• %System%\Driver\Printer\LX300\akses.ico
• %System%\Driver\Printer\LX300\com.ico
• %System%\Driver\Printer\LX300\CPL.ico
• %System%\Driver\Printer\LX300\doc.ico
• %System%\Driver\Printer\LX300\film.ico
• %System%\Driver\Printer\LX300\Folder.ico
• %System%\Driver\Printer\LX300\IE.ico
• %System%\Driver\Printer\LX300\jpg.ico
• %System%\Driver\Printer\LX300\panel.ico
• %System%\Driver\Printer\LX300\pdf.ico
• %System%\Driver\Printer\LX300\pps.ico
• %System%\Driver\Printer\LX300\ppt.ico
• %System%\Driver\Printer\LX300\setup.ico
• %System%\Driver\Printer\LX300\setup2.ico
• %System%\Driver\Printer\LX300\txt.ico
• %System%\Driver\Printer\LX300\winamp.ico
• %System%\Driver\Printer\LX300\winrar.ico
• %System%\Driver\Printer\LX300\winzip.ico
• %System%\Driver\Printer\LX300\xls.ico
• %System%\shell.exe
• %System%\userinit.exe,
• %SystemDrive%\49U5T1N4.exe
• %SystemDrive%\Renungan Illahi.txt
• %SystemDrive%\Renungan Illahi.txt.exe
• %SystemDrive%\Documents and Settings\All Users\Start Menu\Programs\Startup\Microsoft Office.pif
• %SystemDrive%\Documents and Settings\All Users\Start Menu\Programs\Startup\Hayalan.exe
• %SystemDrive%\Perenungan Illahi.txt

Next, the worm creates the following registry entries so that it executes whenever Windows starts:

• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\"LogonAdministrator" = "C:\Documents and Settings\Administrator\Local Settings\Application Data\WINDOWS\CSRSS.EXE"
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\"System Monitoring" = "C:\Documents and Settings\Administrator\Local Settings\Application Data\WINDOWS\LSASS.EXE"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\49U5T1N4" = "C:\WINDOWS\49U5T1N4.exe"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\MSMSGS" = "C:\Documents and Settings\Administrator\Local Settings\Application Data\WINDOWS\WINLOGON.EXE"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\ServiceAdministrator" = "C:\Documents and Settings\Administrator\Local Settings\Application Data\WINDOWS\SERVICES.EXE"

The worm then creates the following registry entries:

• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\inifile\shell\open\command\"" = ""C:\WINDOWS\system32\shell.exe" "%1" %*"
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\SystemFileProtection\"ShowPopups" = "0"
• HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Installer\"LimitSystemRestoreCheckpointing" = "1"
• HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Installer\"DisableMSI" = "1"

It creates the following registry entries to disable the Command Line prompt, the Windows Task Manager, and Registry Editor:

• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\DisableCMD" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\DisableTaskMgr" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\DisableRegistryTools" = "1"
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system\"DisableTaskMgr" = "1"
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system\"DisableRegistryTools" = "1"

It also creates the following registry entries to disable System Restore:

• HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\SystemRestore\"DisableConfig" = "1"
• HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\SystemRestore\"DisableSR" = "1"

The worm creates the following registry entries to disable certain features in Microsoft Explorer:

• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoRun" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoLogoff" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoFind" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoTrayContextMenu" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoViewContextMenu" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\"ShowSuperHidden" = "0"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoFolderOptions" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoClose" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoDesktop" = "1"
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\"NoFolderOptions" = "1"

Next, the worm modifies the following registry entries so that it executes whenever Windows starts:

• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Shell" = "Explorer.exe "C:\WINDOWS\system32\IExplorer.exe""
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Userinit" = "C:\WINDOWS\system32\userinit.exe,C:\WINDOWS\system32\IExplorer.exe"

It also modifies the following registry entries:

• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\batfile\shell\open\command\"" = ""C:\WINDOWS\system32\shell.exe" "%1" %*"
• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\comfile\shell\open\command\"" = ""C:\WINDOWS\system32\shell.exe" "%1" %*"
• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Excel.Sheet.8\"" = "Application"
• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Excel.Sheet.8\DefaultIcon\"" = "C:\WINDOWS\49U5T1N4.exe"
• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\exefile\"" = "Microsoft Corporation"
• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\piffile\shell\open\command\"" = ""C:\WINDOWS\system32\shell.exe" "%1" %*"
• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Word.Document.8\"" = "Application"
• HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Word.Document.8\DefaultIcon\"" = "C:\WINDOWS\49U5T1N4.exe"
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug\"Auto" = "1"
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug\"Debugger" = ""C:\WINDOWS\system32\Shell.exe""
• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\"AlternateShell" = "C:\WINDOWS\49U5T1N4.exe"
• HKEY_CURRENT_USER\Control Panel\Desktop\"SCRNSAVE.EXE" = "C:\WINDOWS\system32\COOLLM~1.SCR"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\"Hidden" = "1"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\"HideFileExt" = "0"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoDriveTypeAutoRun" = "0x000000B5"

The worm then scans all accessible drives on the compromised computer for files with the following extensions:

• .3gp
• .bmp
• .db
• .dbf
• .doc
• .docx
• .gif
• .htm
• .html
• .jpg
• .mdb
• .mdbx
• .mov
• .mp3
• .pdf
• .pps
• .ppt
• .pptx
• .rar
• .rm
• .rtf
• .sql
• .txt
• .wav
• .xls
• .xlsx
• .zip

The worm copies all of the files that it finds to the following location with the following file name format:
%Windir%\Approot\49U5T1N4[35 BLANK SPACES][12 RANDOM CHARACTERS].inf

It then replaces the files that it found with copies of itself and keeps the icon of the original file.

The worm may also copy itself to all local and removable drives as the following files:

• %DriveLetter%\49U5T1N4\Folder.htt
• %DriveLetter%\49U5T1N4\Folderku.exe
• %DriveLetter%\Data Penting.exe
• %DriveLetter%\Setup DirectX 9.0.exe
• %DriveLetter%\Avast Premium Full.exe
• %DriveLetter%\Desktop.ini

It may also create the following file on all local and removable drives so that it executes whenever the drive is accessed:
%DriveLetter%\Autorun.inf

Next, the worm attempts to end the following processes:

• ashmaisv.exe
• aswupdsv.exe
• avgemc.exe
• ccapps.exe
• cclaw.exe
• cyrax.exe
• dkernel.exe
• iexplorer.exe
• killvb.exe
• mcvsescn.exe
• msconfig.exe
• nipsvc.exe
• njeeves.exe
• nvcoas.exe
• pcmav.exe
• poproxy.exe
• procexp.exe
• regcleanr.exe
• regedit.exe
• riyani_jangkaru.exe
• rstrui.exe
• syslove.exe
• systray.exe
• taskmgr.exe
• thunderbird.exe
• tskmgr.exe
• xpshare.exe

It may also attempt to end any process containing the following words:

• adult
• alert
• anal
• ant
• assemb
• avast
• avg
• bit
• black
• builder
• c++
• center
• cillin
• clean
• cmd.
• command
• control
• debug
• demo
• detec
• film
• firewall
• Form1
• free
• fuck
• Gasak
• grisoft
• hack
• hijackthis
• ice
• jap
• kama
• kill
• machine
• mal
• malware
• models
• naked
• nod32
• norman
• norton
• nude
• oral
• panda
• patch
• porn
• proc
• protect
• ray
• reg
• rem
• Remov
• rest
• rootkit
• S m a d A V
• scan
• sec
• sophos
• sword
• symantec
• sysinternals
• system configuration
• task
• tool
• trojan
• tune
• tweak
• util
• vaksin
• video
• vir
• Visual Basic
• W32
• warez
• xxx

The worm may also open Notepad and start typing a message in it in the Indonesian language.

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.

Summary