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Category 1
Discovered on: January 24, 2001
Last Updated on: April 15, 2002 04:51:34 PM

PHP.Sysbat is a Trojan horse, not a virus. Trojan horses do not replicate. PHP.Sysbat only executes on computers with PHP interpreters. (PHP is a server-side, cross-platform, HTML-embedded scripting language.) It cannot be contracted by simply visiting an infected Web page.

PHP.Sysbat modifies the Autoexec.bat file so that the next time the computer is restarted, the command to format the hard drive is executed. The Trojan will also append text to C:\Config.sys and to other files with the .sys extension that are located in the C:\Windows\Command folder. Finally, the Trojan tries to delete C:\Windows\System\Wsock32.dll.

Type: Trojan Horse
Infection Length: 1951

  • Virus Definitions (Intelligent Updater)
  • January 25, 2001

    threat assessment


    Threat Metrics

    Low Medium Low





    technical details

    When executed, the PHP.Sysbat Trojan does the following:

    1. It checks to see if the Config.sys file has been modified. If it has not been modified, the text

      Xmorfic,, Second PHP VIRUS

      is added to the end of the file. (The x's represent a specific Web address).
    2. It checks to see if the Autoexec.bat file has been modified. If it has not been modified, the text

      ctty nul
      format c: /autotest /q /u

      is added to the Autoexec.bat file. This will format the drive C the next time the computer is restarted.
    3. It appends the following text to all .sys files that are located in the C:\Windows\Command folder:

    4. It then attempts to delete the C:\Windows\System\Wsock32.dll file.
    5. Finally, the Trojan displays the text

      This program performed an illegal operation


    Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

    • Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
    • If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
    • 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.
    • Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
    • Isolate infected computers quickly to prevent further compromising your organization. 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.

    removal instructions

    To remove this Trojan:

    1. Run LiveUpdate to make sure that you have the most recent virus definitions.
    2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
    3. If any files are detected as infected by PHP.Sysbat, you need to delete them.
    4. Remove the following text from the Autoexec.bat file:

      ctty nul
      format c: /autotest /q /u

      CAUTION: Do not restart the computer until you have removed this text.
    5. Restore from backup or reinstall all .sys files that were infected by the Trojan.
    6. Replace the Wsock32.dll file, if necessary.

    Write-up by: Eric Chien