1. Vulnerability Description

• If Cookie’s scope is not Fully Qualified Domain Name, attacker can use this cookie to connect to other domains, such as subdomain.
• An attacker can gain access to pages in the subdomain group by taking one cookie from anywhere.

2. Vulnerability Countermeasure

• Cookie scope must be set to Fully Qualified Domain Name.
• If there is a subdomain that is not in use, you must delete it.
• Cookie must always set the HttpOnly and Secure properties.
• Make sure that the validity period of the cookie is not set too long.