PHP.Carac

When PHP.Carac is first executed, it will look for an mIRC Script.ini file in:

• C:\Mirc
• C:\Mirs32
• C:\ProgramFiles\Mirc

If it is found, additional commands will be added to the Script.ini file so that the Ms.php file is sent to others who connect to the same channel as the infected computer. Then, if the C:\Msphp\Msphp.ini exists, the following text will be appended to it every time that the virus is executed:

[MSPHP]
Microsoft PHP Support
This folder and the ms.php file into it will help your computer
and you web browser to move one step more into the world of PHP.
Microsoft wants you to enjoy the high technology available on the
net in this day, so to make this ability Microsoft developed a new
product named MSPHP that will help you and your computer to know
the PHP language.
This folder was created automaticly bu MSInternetExplorer Live Update
if you want to uninstall this options do not delete the folder or the
file because then you may cause damage to your computer just send email
to msphp@microsoft.com and we will tell you how to uninstall it.
Copyright Microsoft (c) 2001

The virus then deletes the Msdos.sys and Config.sys files and replace them with new files containing new text. It then deletes the following files:

• C:\Windows\Regedit.exe
• C:\Windows\System\Mshtml.dll
• C:\Windows\System\Wsock.vxd
• C:\Windows\System\Winspool.drv
• C:\Windows\System\Vxblock.dll

After deleting these files, the virus will search in the same folder that the virus is in for .htm, .html, and .php files. These files will be infected if the file name is not Caracula.php. The infection technique is to append a PHP include directive. This is the same technique used by PHP.Pirus. Then the virus searches in the C:\Windows\System folder for files with the .sys, .vxd, .bat, .exe, and .ocx extensions, and append the following text to them:

Are you read to slide with Caracula ??? I'm ready but you don't!!! PHP.Caracula - slide now

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