PHP.io

SUMMARY

PHP.io is a virus that is written in the PHP scripting language. (PHP is a server-side scripting language that is used for dynamic Web page generation.) This virus only executes on computers that have PHP interpreters; it cannot be contracted simply by visiting an infected Web page.

Protection

• Virus Definitions (Intelligent Updater) February 19, 2001

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

During execution this virus creates (and overwrites if it already exists) the C:Autoexec.bat file, and then inserts the file C:WindowsSystem32io.vbs.

In both cases, because of bugs in the virus code, the inserted files do not execute; they contain corrupted versions of executable code for that file type (.bat and .vbs respectively).

If it had been written correctly, the Autoexec.bat file would have executed the io.vbs file at system startup, and the io.vbs file would have contained a copy of an active .vbs virus.

This virus will also append to all files in the current folder a PHP-scripting call to itself (the currently executing script name is used in this call). (The virus tries to filter the files to just .php, .html, and .htm files, but due to another bug, the result is all files.)

This virus also appends the string "ioioioioioioioooioioioioioiioiooioioioioioioioioioioioioioioioioioioioioioioioiioi" to all .inf files in the C:WindowsInf folder.

Next, the current script is renamed to Os67830.sys, effectively making previously inserted PHP-script calls invalid.

Finally, just before exiting, the script this virus will print the following text:

PHP.Io is an anti-virus test program that was created to make the internet more safty
and to protect you againts new php virus

Recommendations

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

To remove the virus:

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. Delete the following files:
   • The file detected as PHP.io (probably the Os67830.sys file).
   • The file detected as VBS.io.Intended (the io.vbs file).
4. Delete, and then restore from backup, all files detected as PHP.io.inc.