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Tuesday, May 7, 2013

Bypassing Geo-locked BYOD Applications


By Gunter Ollmann, @gollmann

In the wake of increasingly lenient BYOD policies within large corporations, there’s been a growing emphasis upon restricting access to business applications (and data) to specific geographic locations. Over the last 18 months more than a dozen start-ups in North America alone have sprung up seeking to offer novel security solutions in this space – essentially looking to provide mechanisms for locking application usage to a specific location or distance from an office, and ensuring that key data or functionality becomes inaccessible outside these prescribed zones.

These “Geo-locking” technologies are in hot demand as organizations try desperately to regain control of their networks, applications and data.


Over the past 9 months I've been asked by clients and potential investors alike for advice on the various technologies and the companies behind them. There’s quite a spectrum of available options in the geo-locking space; each start-up has a different take on the situation and has proposed (or developed) a unique way in tackling the problem. Unfortunately, in the race to secure a position in this evolving security market, much of the literature being thrust at potential customers is heavy in FUD and light in technical detail.

It may be because marketing departments are riding roughshod over the technical folks in order to establish these new companies, but in several of the solutions being proposed I've had concerns over the scope of the security element being offered. It’s not because the approaches being marketed aren't useful or won’t work, it’s more because they've defined the problem they’re aiming to solve so narrowly that they've developed what I could only describe as tunnel-vision to the spectrum of threat organizations are likely to face in the BYOD realm. 

In the meantime I wanted to offer this quick primer on the evolving security space that has become BYOD geo-locking.

Geo-locking BYOD
The general premise behind the current generation of geo-locking technologies is that each BYOD gadget will connect wirelessly to the corporate network and interface with critical applications. When the device is moved away from the location, those applications and data should no longer be accessible.

There are a number of approaches, but the most popular strategies can be categorized as follows:
  1. Thick-client – A full-featured application is downloaded to the BYOD gadget and typically monitors physical location elements using telemetry from GPS or the wireless carrier directly. If the location isn’t “approved” the application prevents access to any data stored locally on the device.
  2. Thin-client – a small application or driver is installed on the BYOD gadget to interface with the operating system and retrieve location information (e.g. GPS position, wireless carrier information, IP address, etc.). This application then incorporates this location information in to requests to access applications or data stored on remote systems – either through another on-device application or over a Web interface.
  3. Share-my-location – Many mobile operating systems include opt-in functionality to “share my location” via their built-in web browser. Embedded within the page request is a short geo-location description.
  4. Signal proximity – The downloaded application or driver will only interface with remote systems and data if the wireless channel being connected to by the device is approved. This is typically tied to WiFi and nanocell routers with unique identifiers and has a maximum range limited to the power of the transmitter (e.g. 50-100 meters).
The critical problem with the first three geo-locking techniques can be summed up simply as “any device can be made to lie about its location”.

The majority of start-ups have simply assumed that the geo-location information coming from the device is correct – and have not included any means of securing the integrity of that device’s location information. A few have even tried to tell customers (and investors) that it’s impossible for a device to lie about its GPS location or a location calculated off cell-tower triangulation. I suppose it should not be a surprise though – we’ve spent two decades trying to educate Web application developers to not trust client-side input validation and yet they still fall for web browser manipulations.

A quick search for “fake location” on the Apple and Android stores will reveal the prevalence and accessibility of GPS fakery. Any other data being reported from the gadget – IP address, network MAC address, cell-tower connectivity, etc. – can similarly be manipulated. In addition to manipulation of the BYOD gadget directly, alternative vectors that make use of private VPNs and local network jump points may be sufficient to bypass thin-client and “share-my-location” geo-locking application approaches.

That doesn't mean that these geo-locking technologies should be considered unicorn pelts, but it does mean that organization’s seeking to deploy these technologies need to invest some time in determining the category of threat (and opponent) they’re prepared to combat.

If the worst case scenario is of a nurse losing a hospital iPad and that an inept thief may try to access patient records from another part of the city, then many of the geo-locking approaches will work quite well. However, if the scenario is that of a tech-savvy reporter paying the nurse to access the hospital iPad and is prepared in install a few small applications that manipulate the geo-location information in order to remotely access celebrity patient records… well, then you’ll need a different class of defense.

Given the rapid evolution of BYOD geo-locking applications and the number of new businesses offering security solutions in this space, my advice is two-fold – determine the worst case scenarios you’re trying to protect against, and thoroughly assess the technology prior to investment. Don’t be surprised if the marketing claims being made by many of these start-ups are a generation or two ahead of what the product is capable of performing today.

Having already assessed or reviewed the approaches of several start-ups in this particular BYOD security realm, I believe some degree of skepticism and caution is warranted.

-- Gunter Ollmann, CTO IOActive

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