如果我們不關閉 cgi.fix_pathinfo，伺服器是否仍然容易受到攻擊？

nginx安裝自帶的/etc/nginx/sites-available/default文件有以下內容：

# You may add here your
# server {
#   ...
# }
# statements for each of your virtual hosts to this file

##
# You should look at the following URL's in order to grasp a solid understanding
# of Nginx configuration files in order to fully unleash the power of Nginx.
# http://wiki.nginx.org/Pitfalls
# http://wiki.nginx.org/QuickStart
# http://wiki.nginx.org/Configuration
#
# Generally, you will want to move this file somewhere, and start with a clean
# file but keep this around for reference. Or just disable in sites-enabled.
#
# Please see /usr/share/doc/nginx-doc/examples/ for more detailed examples.
##

server {
   listen 80 default_server;
   listen [::]:80 default_server ipv6only=on;

   root /usr/share/nginx/html;
   index index.html index.htm;

   # Make site accessible from http://localhost/
   server_name localhost;

   location / {
       # First attempt to serve request as file, then
       # as directory, then fall back to displaying a 404.
       try_files $uri $uri/ =404;
       # Uncomment to enable naxsi on this location
       # include /etc/nginx/naxsi.rules
   }

   # Only for nginx-naxsi used with nginx-naxsi-ui : process denied requests
   #location /RequestDenied {
   #   proxy_pass http://127.0.0.1:8080;    
   #}

   #error_page 404 /404.html;

   # redirect server error pages to the static page /50x.html
   #
   #error_page 500 502 503 504 /50x.html;
   #location = /50x.html {
   #   root /usr/share/nginx/html;
   #}

   # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
   #
   #location ~ \.php$ {
   #   fastcgi_split_path_info ^(.+\.php)(/.+)$;
   #   # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini
   #
   #   # With php5-cgi alone:
   #   fastcgi_pass 127.0.0.1:9000;
   #   # With php5-fpm:
   #   fastcgi_pass unix:/var/run/php5-fpm.sock;
   #   fastcgi_index index.php;
   #   include fastcgi_params;
   #}

   # deny access to .htaccess files, if Apache's document root
   # concurs with nginx's one
   #
   #location ~ /\.ht {
   #   deny all;
   #}
}


# another virtual host using mix of IP-, name-, and port-based configuration
#
#server {
#   listen 8000;
#   listen somename:8080;
#   server_name somename alias another.alias;
#   root html;
#   index index.html index.htm;
#
#   location / {
#       try_files $uri $uri/ =404;
#   }
#}


# HTTPS server
#
#server {
#   listen 443;
#   server_name localhost;
#
#   root html;
#   index index.html index.htm;
#
#   ssl on;
#   ssl_certificate cert.pem;
#   ssl_certificate_key cert.key;
#
#   ssl_session_timeout 5m;
#
#   ssl_protocols SSLv3 TLSv1 TLSv1.1 TLSv1.2;
#   ssl_ciphers "HIGH:!aNULL:!MD5 or HIGH:!aNULL:!MD5:!3DES";
#   ssl_prefer_server_ciphers on;
#
#   location / {
#       try_files $uri $uri/ =404;
#   }
#}

你可以看到有一條註​​釋“你應該有”cgi.fix_pathinfo = 0; 在 php.ini" 中。在它上面，我們還有這一行：

fastcgi_split_path_info ^(.+\.php)(/.+)$;

根據 Nginx, PHP & fastcgi_split_path_info 上的安全問題，我們可以通過關閉或使用.cgi.fix_pathinfo``fastcgi_split_path_info

既然它已經使用fastcgi_split_path_info指令來應對這種漏洞，為什麼它仍然說我們應該關閉cgi.fix_pathinfo？如果我們不這樣做，我們的伺服器是否容易受到攻擊？

關於 PHP-FPM 配置的 Nginx wiki頁面建議打開cgi.fix_pathinfo。注意使用的正則表達式：

fastcgi_split_path_info ^(.+?\.php)(/.*)$;

該頁面還提供了一個測試，您可以訪問下面列出的不同 URL，並檢查 REQUEST_URI、SCRIPT_NAME、PATH_INFO 和 PHP_SELF 的正確值。

/test.php
/test.php/
/test.php/foo
/test.php/foo/bar.php
/test.php/foo/bar.php?v=1 

test.php 只包含<?php var_export($_SERVER)?>. 這有助於確定您的設置是否安全。在所有 URL 上，您的 SCRIPT_NAME 應該是test.php。在任何情況下，您都不應該在那裡看到bar.php。

引用自：https://serverfault.com/questions/623999