XSS - Session hijacking

Discussion in 'ASP .Net Security' started by Robert Slaney, Feb 5, 2009.

  1. note - using ASP.NET 2.0

    I would like to set the httponly cookie flag on the asp.net sessionid
    cookie. I know I can set this via the httpCookies element in web.config, but
    I don't want to set all cookies to have this flag.

    I have some cached static pages that use values from the cookies in
    javascript so until I can reengineer these pages to remove this I cannot set
    the web.config in this way.

    Does the default asp.net session provider have the ability to set it's
    cookie to HttpOnly ?


    Robert Slaney, Feb 5, 2009
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  2. I think that it is set already, FireBug with firecookie shows the HttpOnly
    attribute is on for ASPNET_SessionID.
    Robert Slaney, Feb 5, 2009
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  3. Robert Slaney

    Steven Cheng Guest

    Hi Rob,

    As for the SessionID cookie, it is generated internally by the default
    sessionIdManager. You can find the internal code logic through reflector.
    Here is the code snippet extract from it:

    ======default SessionIdManager class======

    private static HttpCookie CreateSessionCookie(string id)
    HttpCookie cookie = new HttpCookie(Config.CookieName, id);
    cookie.Path = "/";
    cookie.HttpOnly = true;
    return cookie;


    As you can see, it explicitly set HttpOnly to true. Also, I've tested the
    session cookie via some javascript, and the javascript code cannot retrieve
    it, that also indicate the cookie is httpOnly and protected from


    Steven Cheng

    Microsoft MSDN Online Support Lead

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    Steven Cheng, Feb 5, 2009
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