W32.Wowinzi.A

The worm may be downloaded from compromised Web sites.

Once executed, the worm copies itself as the following files:

• %System%\windows.txt
• %Windir%\Tasks\0x01xx8p.exe

The worm then creates the following files:

• %Windir%\Tasks\SysFile.brk (copy of spoolsv.exe)
• %Windir%\Tasks\spoolsv.ext (copy of spoolsv.exe)

It then modifies the following files:

• %System%\dllcache\spoolsv.exe
• %System%\spoolsv.exe

The following threats may then be dropped and executed on the compromised computer:

• %Temp%\dat[RANDOM HEX NUMBER].tmp (Hacktool.Rootkit)
• %Temp%\dat[RANDOM HEX NUMBER].tmp (Infostealer.Gampass)

The worm then copies itself to all fixed and removable drives as the following file:
%DriveLetter%\MSDOS.bat

The worm also creates the following file on all fixed and removable drives so that it executes whenever the drive is accessed:
%DriveLetter%\autorun.inf

It deletes the following file:
%System%\verclsid.exe

The worm creates the following registry entry, so that it runs every time Windows starts:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"Shell" = "%System%\Rundll32.exe %System%\shell32.dll Control_RunDLL %Temp%\dat[RANDOM HEX NUMBER].tmp"

The worm also creates the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Data\Config\"http://winzipices.cn/1.exe" = "http://winzipices.cn/1.exe"
HKEY_CURRENT_USER\_reg\"Shell" = "%System%\Rundll32.exe %System%\shell32.dll Control_RunDLL %Temp%\dat[RANDOM 4 DIGIT HEX NUMBER].tmp"
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Desktop\"RxMru" = [BINARY DATA]
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Desktop\"mrulist" =" %Temp%\dat[RANDOM 4 DIGIT HEX NUMBER].tmp"
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Desktop\"sysfile" = "%System%\1.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{E25C29AB-12B9-4523-A53C-324B5FBA648C}\InProcServer32\"(Default Value)" = "%Temp%\dat[RANDOM HEX NUMBER].tmp"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellExecuteHooks\"{E25C29AB-12B9-4523-A53C-324B5FBA648C}" = "0"

It contacts the following URL to retrieve configuration information:
[http://]winzipices.cn/confi[REMOVED]

The worm may then perform any of the following actions based on information in the configuration file:

• Download and execute a file
• Gather email addresses from files
• Attempt to infect executable files
• Copy itself to removable and network drives
• Attempts to spread through network shares
• Inject malicious code into local network user Web pages and into Web pages on the compromised computer

It then downloads and executes a copy of itself as the following executable:
[http://]winzipices.cn/[REMOVED]

Currently, the worm will post confidential information to the following remote location:
[http://]winzipices.cn/tong/post[REMOVED]

The worm opens a back door and may attempt to contact the following remote location on TCP port 1800:
61.134.37.15

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