nginx服务器防sql注入与溢出(一)

代码不可能是全完美的，动态网页在实用中难免会遇到sql注入的攻击。而通过nginx的配置过滤，可以很好的避免被攻击的可能。SQL注入攻击一般问号后面的请求参数，在nginx里用$query_string表示 。

一、特殊字符过滤

例如URL /plus/list.php?tid=19&mid=22′ ，后面带的单引号为非法的注入常用字符。而想避免这类攻击，可以通过下面的判断进行过滤。

if ( $query_string ~* ".*[;'<>].*" ) {
return 404;
}

二、sql语句过滤

if (request_uri ~* "(cost()|(concat()") {
                 return 444;
         }
         if (request_uri ~* "[+|(%20)]union[+|(%20)]") {
                 return 444;
         }
         if (request_uri ~* "[+|(%20)]and[+|(%20)]") {
                 return 444;
         }
         if (request_uri ~* "[+|(%20)]select[+|(%20)]") {
                 return 444;
         }

三、文件注入禁止

set block_file_injections 0;
if (query_string ~ “[a-zA-Z0-9_]=http://”) {
set block_file_injections 1;
}
if (query_string ~ “[a-zA-Z0-9_]=(..//?)+”) {
set block_file_injections 1;
}
if (query_string ~ “[a-zA-Z0-9_]=/([a-z0-9_.]//?)+”) {
set block_file_injections 1;
}
if (block_file_injections = 1) {
return 444;
}

四、溢出攻击过滤

set block_common_exploits 0;
if (query_string ~ “(<|%3C).*script.*(>|%3E)”) {
set block_common_exploits 1;
}
if (query_string ~ “GLOBALS(=|[|%[0-9A-Z]{0,2})”) {
set block_common_exploits 1;
}
if (query_string ~ “_REQUEST(=|[|%[0-9A-Z]{0,2})”) {
set block_common_exploits 1;
}
if (query_string ~ “proc/self/environ”) {
set block_common_exploits 1;
}
if (query_string ~ “mosConfig_[a-zA-Z_]{1,21}(=|%3D)”) {
set block_common_exploits 1;
}
if (query_string ~ “base64_(en|de)code(.*)”) {
set block_common_exploits 1;
}
if (block_common_exploits = 1) {
return 444;
}

五、spam字段过滤

set block_spam 0;
if (query_string ~ “b(ultram|unicauca|valium|viagra|vicodin|xanax|ypxaieo)b”) {
set block_spam 1;
}
if (query_string ~ “b(erections|hoodia|huronriveracres|impotence|levitra|libido)b”) {
set block_spam 1;
}
if (query_string ~ “b(ambien|bluespill|cialis|cocaine|ejaculation|erectile)b”) {
set block_spam 1;
}
if (query_string ~ “b(lipitor|phentermin|pro[sz]ac|sandyauer|tramadol|troyhamby)b”) {
set block_spam 1;
}
if (block_spam = 1) {
return 444;
}

六、user-agents头过滤

set block_user_agents 0;
if (http_user_agent ~ “Wget”) {
 set block_user_agents 1;
}
# Disable Akeeba Remote Control 2.5 and earlier
if (http_user_agent ~ “Indy Library”) {
set block_user_agents 1;
}
# Common bandwidth hoggers and hacking tools.
if (http_user_agent ~ “libwww-perl”) {
set block_user_agents 1;
}
if (http_user_agent ~ “GetRight”) {
set block_user_agents 1;
}
if (http_user_agent ~ “GetWeb!”) {
set block_user_agents 1;
}
if (http_user_agent ~ “Go!Zilla”) {
set block_user_agents 1;
}
if (http_user_agent ~ “Download Demon”) {
set block_user_agents 1;
}
if (http_user_agent ~ “Go-Ahead-Got-It”) {
set block_user_agents 1;
}
if (http_user_agent ~ “TurnitinBot”) {
set block_user_agents 1;
}
if (http_user_agent ~ “GrabNet”) {
set block_user_agents 1;
}
if (block_user_agents = 1) {
return 444;
}
}

注：之所以返回444,是因为其完全不回应客户端，比403或404等更加非常节省系统资源。