public class RedirectUserToChangedPassword : HttpRequestProcessor
{
    private TimeSpan TimeSpanToExpirePassword { get; set; }
    private string ChangePasswordPageUrl { get; set; }

    public override void Process(HttpRequestArgs args)
    {
        if (((Sitecore.Context.PageMode.IsNormal || Sitecore.Context.PageMode.IsPreview)
                && Sitecore.Context.Site != null
                //custom method: IsContentSite
                && Sitecore.Context.Site.IsContentSite())
            || Sitecore.Context.User == null
            || Sitecore.Context.User.IsAdministrator
            || args.Url == null
            || String.Equals(args.Url.FilePath, ChangePasswordPageUrl, StringComparison.CurrentCultureIgnoreCase))
            return;

        var membershipUser = Membership.GetUser(Sitecore.Context.User.Name, false);

        if (!HasPasswordExpired(membershipUser))
            return;

        var queryString = new NameValueCollection();
        queryString.Add(Constants.Sitecore.ChangePassword.OriginalUrlKey, args.Url.FilePathWithQueryString);

        //custom method: ToQueryString
        WebUtil.Redirect(ChangePasswordPageUrl + (ChangePasswordPageUrl.Contains("?") ? "&" : "?") + queryString.ToQueryString());
    }

    private bool HasPasswordExpired(MembershipUser user)
    {
        return user.LastPasswordChangedDate.Add(TimeSpanToExpirePassword) <= DateTime.Now;
    }
}

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
    <sitecore>
      <pipelines>
        <httpRequestBegin>
          <processor type="MyDll.CustomSitecore.Pipelines.HttpRequest.RedirectUserToChangedPassword, MyDll"
                     patch:after="*[@type='Sitecore.Pipelines.HttpRequest.UserResolver, Sitecore.Kernel']">
            <TimeSpanToExpirePassword>00:00:01:00</TimeSpanToExpirePassword>
            <ChangePasswordPageUrl>/sitecore/shell/Applications/Security/ChangePassword/customchangepassword.aspx</ChangePasswordPageUrl>
          </processor>
        </httpRequestBegin>
      </pipelines>
    </sitecore>
  </configuration>

public class ChangePasswordPage : Sitecore.Shell.Applications.Security.ChangePassword.ChangePasswordPage
{
    protected override void OnLoad(EventArgs e)
    {
        base.OnLoad(e);
        ChangePassword.ContinueButtonClick += ChangePassword_ContinueButtonClick;
    }

    private void ChangePassword_ContinueButtonClick(object sender, EventArgs e)
    {
        Sitecore.Diagnostics.Assert.ArgumentNotNull(sender, "sender");
        Sitecore.Diagnostics.Assert.ArgumentNotNull(e, "e");

        var originalUrl = Request.QueryString[Constants.Sitecore.ChangePassword.OriginalUrlKey];
        if (!originalUrl.IsNullOrEmpty())
        {
            WebUtil.Redirect(originalUrl);
        }
        else if (Sitecore.Context.User != null)
        {
            WebUtil.Redirect(Sitecore.Context.User.Profile.StartUrl);
        }
        else
        {
            WebUtil.RedirectToLoginPage();
        }
    }
}