RE: Single terminal login

["Michael Silk" <silkm () hushmail com>]

Steve,

 An idea comes to mind ...

 I don't know what language you're using, but in java
 or .net it is easy to implement a static list of all
 the current "logged in" users.

 You can, at "logging in" point, create a "user" type object,
 with "lastActivity" field, add it to the list, and update 
 this object, not a database or LDAP, with the time of access.

 You can then also have a server thread that sits in the
 background "logging out" these objects after some time period.

 The time period will be easy to figure out based on the type
 of application you use.

-- Michael


-----Original Message-----
From: stevenr () mastek com [mailto:stevenr () mastek com]
Sent: Tuesday, 17 February 2004 12:58 PM
To: urbn () visi com
Cc: webappsec () securityfocus com
Subject: RE: Single terminal login


Hi
 
Updating the timestamp in the DB is a general workaround, but as I mentioned
in my first post, if I update the DB for every page accessed, it will
be a very expensive method for a high volume site.
 
Also, what Matt suggested about closing the prev session with every new
login does make sense, but that would mean that a user would get in every
time, invalidating the prev session. To give a background, I need to
implement the Single Terminal Login concept to avoid password sharing
among users, which is playing havoc with my audit trails. This method
would work towards solving that, but the user will not realise that someone
else is logged in from his/her account previously, possibly meaning a
stolen password etc. 
 
Regards
Steve 
 

        -----Original Message----- 
        From: urbn () visi com [mailto:urbn () visi com] 
        Sent: Tue 2/17/2004 1:07 AM 
        To: Steven Rebello 
        Cc: webappsec () securityfocus com 
        Subject: Re: Single terminal login
        
        

         One factor you didn't mention is server resources issues, do you mind
these
        
         sessions staying in memory for... hours?
        
         What I have done in the past is store user information in a database,
 and
         include a record that tracks the last time the database was accessed
(each
         time
         a page is accessed or refreshed) a script is run to update this field.
        
         2 main fields, a filed that stores if they are logged in, and a field
that
         stores a time (last time page access). 
        
         When the user tries to login, if this field is less then say 5 minutes
old
         (preset time), they can not login.  After five minutes, if they are
listed as
        
         Logged in, they receive a warning they did not log off correctly and
must
        type
         in their password again.
        
         Don't really know if that was what you are looking for, because you
run into
        
         issues with sessions being killed once the browser is closed, timeout
issues
         on
         the server side, and many more issues.
        
        
        > Quoting Matt Wirges <wirges () purdue edu>:
        >
        > > stevenr () mastek com wrote:
        > > > Hi
        > > >
        > > > I have worked with web based applications since quite some time.
One
        > issue
        > > to which I have not found a satisfactory answer yet is that of a
problem
        > with
        > > Single Terminal Login in a web based application.
        > > >
        > > > By Single Terminal Login, I mean that if one user logs into a
web
        > > application (say JSP based), s/he should not be able to login from
        > another
        > > machine or even another browser from the same machine. This can
be
        > achieved
        > > easily by setting a "logged in" flag on the server side using a
DB or
        > LDAP
        > > etc. When the user clicks on the Logout link, the flag is reset
and only
        > then
        > > the user can login from another browser/window. Now the hitch. If
the
        > user
        > > closes the browser directly, or the power goes out, or browser hangs
and
        > has
        > > to be killed, the flag remains as "logged in". In short user cannot
login
        > > into the system again. The one workaround used commonly, is setting
a
        > timeout
        > > after which the user can login again, where a "last active time"
is
        > > maintained for each user. Every login request is cross-checked against
        > this
        > > time and if the difference is greater than some threshold value,
 the user
        > is
        > > able to login again.  But this means that everytime the user does
        > something
        > > the "last active
        > > time" will have to be updated, which will be expensive in a high
traffic
        > > site. Also, the threshold value is always a hot topic of debate
:-)
        > > >
        > > > Does anyone know a better or a different approach to this? Would
be
        > helpful
        > > if someone knows some site/papers for this. Have googled but havent
come
        > > across any myself.
        > > >
        > > > - Steve
        > > >
        > > > "He who laughs last probably made a backup..."
        > > >
        > > >
        > > >
        > > > MASTEK
        > > > "Making a valuable difference"
        > > > Mastek in NASSCOM's 'India Top 20' Software Service Exporters
List.
        > > > In the US, we're called MAJESCO
        > > >
        > > >
        > >
        >
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        > > > Opinions expressed in this e-mail are those of the individual
and not
        > that
        > > of Mastek Limited, unless specifically indicated to that effect.
Mastek
        > > Limited does not accept any responsibility or liability for it.
This
        > e-mail
        > > and attachments (if any) transmitted with it are confidential and/or
        > > privileged and solely for the use of the intended person or entity
to
        > which
        > > it is addressed. Any review, re-transmission, dissemination or other
use
        > of
        > > or taking of any action in reliance upon this information by persons
or
        > > entities other than the intended recipient is prohibited. This e-
mail and
        > its
        > > attachments have been scanned for the presence of computer viruses.
It is
        > the
        > > responsibility of the recipient to run the virus check on e-mails
and
        > > attachments before opening them. If you have received this e-mail
in
        > error,
        > > kindly delete this e-mail from all computers.
        > > >
        > >
        >
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        > > >
        > >
        > > Steve,
        > >
        > >    What we've done in the past on a few applications is simply close
the
        > > old session the next time the user logs in.  For example, one of
the
        > > applications I worked on is a web interface for incident response.
 One
        > > of its features is time tracking to see how long a responder has
worked
        > > on an incident.  So if the responder closes his web browser or his
        > > session expires, i.e. he doesn't log out via the application, the
        > > session remains active in the session table until the next time
he logs
        > > in.  When the user logs in again, the system asks him to enter the
time
        > > when he last used it and then closes the session updating it with
his
        > > logout time and initiates the new session.
        > >
        > > In other applications I've simply just auto-closed the session when
a
        > > new login is detected.
        > >
        > >
        > > -matt
        > >
        > > --
        > > Matthew Wirges
        > > IT Security and Policy Analyst
        > > Security and Policy
        > > Information Technology at Purdue
        > > wirges () purdue edu :: (765)49-62307
        > > www.itap.purdue.edu/security
        > >
        >
        >
        >
        
        
        



MASTEK
"Making a valuable difference"
Mastek in NASSCOM's 'India Top 20' Software Service Exporters List.
In the US, we're called MAJESCO

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Opinions expressed in this e-mail are those of the individual and not
that of Mastek Limited, unless specifically indicated to that effect.
Mastek Limited does not accept any responsibility or liability for it.
This e-mail and attachments (if any) transmitted with it are confidential
and/or privileged and solely for the use of the intended person or entity
to which it is addressed. Any review, re-transmission, dissemination
or other use of or taking of any action in reliance upon this information
by persons or entities other than the intended recipient is prohibited.
This e-mail and its attachments have been scanned for the presence of
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