This indicates an attempt to exploit a SQL Injection vulnerability in a Joomla! Component.
The vulnerability is a result of a Joomla! Component's failure to check user supplied input before using it in an SQL query. As a result, a remote attacker can send a crafted query to execute SQL commands on a vulnerable server.
This is a generic signature against web-based SQL injections vulnerability in a Joomla! Component.
System Compromise: Remote attackers can access or modify data in the database of the affected application
Apply the latest patch to the vulnerable software if possible.