[thelist] restricting an account to one device

Ken Schaefer ken at adOpenStatic.com
Fri Jan 10 10:59:51 UTC 2020

To prevent multiple sign-ins, you need to maintain an active session database on the server side.

At the very least, on every login, you check to see if there's an existing active session for that user, and you sign-out any other session (or prevent the new session). This doesn't prevent credential sharing, but it does prevent simultaneous logins. If you are able, check on every page request, rather than just login.

The hoops you are going through below is a different measure. This is likely a risk-based authentication system, where various parameters about your usage patten (browser, mobile device ID, IP address) are used to gauge how likely you are to be who you say you are.

FWIW, I work in IAM architecture at a fairly large bank. There are many ways to, figuratively, skin the cat. The above is the basic way of doing it.


-----Original Message-----
From: thelist <thelist-bounces at lists.evolt.org> On Behalf Of Bob Meetin
Sent: Friday, 10 January 2020 2:26 PM
To: thelist at lists.evolt.org
Subject: [thelist] restricting an account to one device


Since thelist is alive, here's a question that I was thinking to post on stackoverflow but feels more like feedback material.

I have a project, a customer with a paid membership system. The customer wants the security set up so tight that there is no possibility of simultaneous logins - he has referenced online banking systems as a model several times. Curious, I just ran some tests with my online banking thru Chase. I opened up 2 different browsers, one Firefox and the other Chrome.

 1. I signed in with Firefox - entered username and password. It
    recognized me from home so no extra hoops.
 2. I then signed in with Chrome - after entering the username and
    password, it prompted me for hoops as it did not recognize the
    device. I had to go through 3 hoops screens including obtaining a
    code through email (or sms) before I could log in. This worked. Okay.
 3. Just to see I then tried signing in with my phone. I had to go
    through the same hoops as with Chrome but got signed in successfully.

Observation? I was able to sign in with 3 different devices at the same time, simultaneously. The sessions timeout automatically after about
5-10 minutes, but the bank system allows many simultaneous sessions, different devices.

When signed in there is an option to view recent signin history, called AccountSafe. In my case it shows 3 different devices (not really devices but what they call devices). There is one for each desktop browser and another for my phone browser. They are identified as:

Linux x86_64
Linux x86_64
LInux (my android phone)

Recording OS information in itself does not seem like enough to lock down device access. I have a little function for grabbing some information like the following from visitors:

IP address
OS: Linus, Android, etc
Browser: Chrome, Firefox, etc
Device: PC, mobile
Extended OS info: X11; Ubuntu; Linux x86_64; rv:71.0

Next I rebooted my router to get a new IP address and deleted all cookies and session info. This did nothing to restore jumping through hoops of having to reauthenticate. The bank system still recognizes the three devices and prompts for simple username/password access.

Q1) What is the bank doing, recording to allow only those particular devices that I have authenticated. My understanding is that MAC address is not viable.

I am pretty sure I that I can set up a function using either sessions or cookies to detect if someone is currently signed in (maybe using browsing history, etc) and prevent a second person from signing in with the same account unless they go through authentication hoops. Not sure.

Q2) How would you approach preventing multiple simultaneous logins? 
Preferred method?

The goal is to prevent account sharing.



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