Security Tips: How to Effectively Defend PHP Trojan Attacks_PHP Tutorial

1. 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

In this way, if the script wants to read files other than /usr/local/apache/htdocs, it will not be allowed. If the error display is turned on, 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

Wait.

　2. Prevent php Trojan from executing webshell

Turn on safe_mode,

Setting

Disable_functions= passthru, exec, shell_exec, system

You can choose one of the two, or you can choose both

　3. Prevent php Trojan from reading and writing file directories

Disable_functions= passthru, exec, shell_exec, system

Add PHP file processing function at the end

Mainly include

　fopen, mkdir, rmdir, chmod, unlink, dir

　fopen, fread, fclose, fwrite, file_exists

　closedir, is_dir, readdir.opendir

fileperms.copy, unlink, delfile

It 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 the apache is built on the windos platform, we need to pay attention to one thing. By default, apache runs with system permissions, which is scary and makes people feel uncomfortable. Then we should lower the permissions of apache.

net user apache fuckmicrosoft /add

net localgroup users apache /del

OK. We have created a user apche that does not belong to any group.

We open the computer manager, select services, click on the properties of the apache service, we select log on, select this account, we fill in the account and password created above, restart the apache service, ok, apache runs under low privileges .

In fact, we can also set the permissions of each folder so that the apache user can only perform what we want it to do, and create a separate read-write user for each directory. This is also a popular configuration method used by many virtual host providers. However, this method is overkill when used to prevent this.