source: http://www.securityfocus.com/bid/14832/info

ATutor is prone to a remote information disclosure vulnerability. This issue is due to a failure in the application to perform proper access validation before granting access to privileged information.

A remote attacker can exploit this vulnerability and make repeated GET requests for the chat logs, effectively retrieving all chat archives. Information obtained may aid an attacker in further attacks. 

http://www.example.com/atutor/content/chat/2/msgs/1.message
http://www.example.com/atutor/content/chat/2/msgs/2.message
http://www.example.com/atutor/content/chat/2/msgs/3.message