Hacking Problem - ModSecurity: Access denied with code 503

Hacking Problem - ModSecurity: Access denied with code 503
For same days in my “error.log.2010-06-xx” file in LOGS directory I can read a few lines like this: kredit online

[Sun Jun 06 23:31:12 2010] [error] [client 72.47.211.173] تجارة الذهب
ModSecurity: Access denied with code 503 (phase 2). Pattern match “=(http|www|ftp)\:/(.+)\.(c|dat|kek|gif|jpe?g|jpeg|png|sh|txt|bmp|dat|txt|js|html?|tmp|asp)\x20?\?” at REQUEST_URI. [file “… /gotroot/xx_asl_rootkits.conf”] [line “23”] [id “390144”] [rev “2”] [msg “Command shell attack: Generic Attempt to remote include command shell”] [severity “CRITICAL”] [hostname “…”] [uri “…/resource_categories_view.php”] [unique_id “TAySMEWjqY8AAD-Dbp0AAAAI”]
צימרים בצפון

They seems to Hacker Attacks.
After reading the thread in Forum, in my .htaccess file I inserted for all IP of abuse contact (about #20):

allow from all
deny from 72.47.xx … (complete IP)
deny from 77.xx.xx…

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What else can I do?

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You can make sure that you’re running secure software. Blocking an IP address is a waste of time, as you’ve noticed. ModSecurity is plugging one hole. You should make sure that there are no other holes by updating to the latest software on your site.

And make sure your PHP scripts are not vulnerable to injection attacks, and if you don’t run these yet - chkrootkit and rkhunter