This indicates an attack attempt against a Cross Site Scripting vulnerability in phpinfo function of PHP.
The vulnerability is due to insufficient sanitizing of user supplied inputs when handling crafted URI. A remote attacker can exploit this to send a crafted request to a vulnerable server and execute arbitrary code within the context of the webserver.
PHP PHP 4.4.0 and earlier versions
System Compromise: Remote attackers can gain control of vulnerable systems.
Upgrade to the latest version available from the website.