Bridging the Mobile Security Gap: Staring down Network Anarchy (new series)

By Mike Rothman

No rest for the weary, it seems. As soon as we wrapped up last week’s blog series we start two more. Check out Rich’s new DLP series, and today I am starting to dig into the mobile security issue. We will also start up Phase 2 of the Malware Analysis Quant series this week. But don’t cry for us, Argentina. Being this busy is a good problem to have.

We have seen plenty of vendor FUD (Fear, Uncertainty, and Doubt) about mobile security. And the concern isn’t totally misplaced. Those crazy users bring their own devices (yes, the consumerization buzzword) and connect them to your networks. They access your critical data and take that data with them. They lose their devices (or resell them, too often with data still on them), or download compromised apps from an app store, and those devices wreak havoc on your environment. It all makes your no-win your job even harder. Your increasing inability to enforce device standards or ingress paths further impairs your ability to secure the network and the information assets your organization deems important.

Let’s call this situation what is: escalating anarchy. We know that’s a harsh characterization but we don’t know what else to call it. You basically can’t dictate the devices, have little influence of the configurations, must support connections from everywhere, and need to provide access to sensitive stuff. Yep, we stare down network anarchy on a daily basis.

Before we get mired in feelings of futility, let’s get back to your charter as a network security professional. You need to make sure the right ‘people’ (which actually includes devices and applications) access the right stuff at the right times. Of course the powers that be don’t care whether you focus on devices or the network – they just want the problem addressed so they don’t have to worry about it. As long as the CEO can connect to the network and get the quarterly numbers on her iPad from a beach in the Caribbean it’s all good. What could possibly go wrong with that?

Last year we documented a number of these mobile and consumerization drivers, and some ideas on network controls to address the issues, in the paper Network Security in the Age of Any Computing. That research centered around how to put some network controls in place to provide a semblance of order. Things like network segmentation and implementing a ‘vault’ architecture to ensure devices jump through a sufficient number of hoops before accessing important stuff. But that only scratched the surface of this issue. It’s like an iceberg – about 20% of the problems in supporting these consumer-grade devices are apparent. Unfortunately there is no single answer to this issue – instead you need a number of controls to work in concert, in order to offer some modicum of mobile device control. We need to orchestrate the full force of all the controls at our disposal to bridge this mobile security gap.

In this series we will examine both device and network level tactics. Even better, we will pinpoint some of the operational difficulties inherent in making these controls work together, being sure to balance protection against usability.

Before we jump into a short analysis of device-centric controls, it’s time to thank our friends at ForeScout for sponsoring this series. Without our sponsors we’d have no way to pay for coffee, and that would be a huge problem.

Device-centric Controls

When all you have is a hammer, everything looks like a nail, right? It seems like this has been the approach to addressing the security implications of consumerization. Folks didn’t really know what to do, so they looked at mobile device management (MDM) solutions as the answer to their problems. As we wrote in last year’s Mobile Device Security paper (PDF), a device-centric security approach starts with setting policies for who can have certain devices and what they can access. Of course your ability to say ‘no’ has eroded faster than your privacy on the Internet, so you’re soon looking at specific capabilities of the MDM platform to bail you out.

Many organizations use MDM to enforce configuration policies, ensuring they can wipe devices remotely and routing traffic device traffic through a corporate VPN. This helps reduce the biggest risks. Completely effective? Not really, but you need to get through the day, and there have been few weaponized exploits targeting mobile devices, so the risk so far has been acceptable.

But relying on MDM implicitly limits your ability to ensure the right folks get to the right stuff at the right time. You know – your charter as a network security professional. For instance, by focusing on the device you have no visibility into what the user is actually surfing to. The privacy modes available on most mobile browsers make sure there are no tracks left for those who want to, uh, do research on the Internet.

Sure, you might be able to force them through a VPN, but the VPN provides a pass into your network and bypasses your perimeter defenses. Once an attacker is on the VPN with access to your network, they may as well be connected to the network port in your CEO’s office. Egress filtering, DLP, and content inspection can no longer monitor or restrict traffic to and from that mobile device.

What about making sure the mobile devices don’t get compromised? You can check for malware on mobile devices but that has never worked very well for other endpoint devices, and we see no reason to think security vendors have suddenly solved the problems they have been struggling with for decades. You can also (usually) wipe devices if and when you realize they been compromised. But there is a window when the attacker may have unfettered access to your network, which we don’t like.

Compounding these issues, focusing exclusively on devices provides no network traffic visibility. We advocate a Monitor Everything approach, which means you need watch the network for anomalous traffic, which might indicate an attacker in your midst. Device-centric solutions cannot provide that visibility.

But this is not an indictment of MDM. It’s merely a realistic assessment of the limitations of the device-only approach. We have written for years about the need for device hygiene (configuration management and patching) and the need to take devices out of service when you learn they are potentially compromised. MDM provides an essential set of security and management controls. But it’s clearly not a panacea, so you need broader capabilities to bridge this mobile security gap.

In the next post we will examine the network controls you need to look at, how they can be leveraged alongside device-centric controls, and some of the pros and cons of each.

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