Security Settings for nginx anti-SQL injection and file injection

server {[...]     ## Block SQL injections    set $block_sql_injections 0;    if ($query_string ~ "union.*select.*\(") {        set $block_sql_injections 1;    }    if ($query_string ~ "union.*all.*select.*") {        set $block_sql_injections 1;    }    if ($query_string ~ "concat.*\(") {        set $block_sql_injections 1;    }    if ($block_sql_injections = 1) {        return 403;    }     ## Block file injections    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 403;    }     ## Block common exploits    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 403;    }     ## Block spam    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|blue\spill|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 403;    }     ## Block user agents    set $block_user_agents 0;     # Don't disable wget if you need it to run cron jobs!    #if ($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 403;    }}