sharepoint 2010 session fixation/session hijaking issue

Question

One of our security consultant has highlighted a possible session fixation issue in our sharepoint 2010 based portal. and advised us to use "a combination of Session.Abandon and a self-implemented Javascript to implement SessionID’s securely". However we are simple using windows based authentication in our sharepoint 2010 portal and not handling sessions any where? How we can use this approach?