The wide variety of so-called NAC (network access control) products on the market shows a broad range of thinking about policy-based security controls and the management of the network in general, including the end-point devices that connect to the network. Some vendors enforce policies using a client agent, some enforce them in the network, and some even use peers for enforcement. Network-based enforcement itself can take many forms, including dedicated gateway, DHCP manipulation, 802.1x authentication, and port- and VLAN-based enforcement on switches.
In short, there are many ways to skin the NAC cat.
Considering Sophos’ extensive background in managing the security of host systems, you might expect its NAC solution to make use of agent-based enforcement, and you’d be right. However, Sophos also took a decidedly open path to the system, allowing for integration with environments using a wide range of anti-virus agents, 802.1x, DHCP, Cisco NAC, and VPN methods of control and enforcement.
Sophos NAC Advanced combines a Windows Server 2003-based policy management server with end-point agents, dissolvable agents, and reporting to deliver a compelling system for Windows-oriented environments. Although Sophos offers anti-virus software for Mac OS X and Linux as well as Windows, this first release of Sophos NAC Advanced is focused strictly on assessment and policy management for Windows end points.
Policy is king
As in my previous reviews of solutions from ConSentry, Enterasys, McAfee, Symantec, and Trend Micro, I looked at the Sophos product’s ability to address a set of typical enterprise policies and distinguish the ways in which the product does that. When choosing among NAC solutions, the key is to consider your requirements from within the universe of possible policies, especially in terms of the granularity of both the policies and their enforcement. You will also want to consider how (and how frequently) you want to interact with the system and whether ease of policy creation, policy modification, or reporting are your most vital requirements.
Sophos takes a hierarchical approach to policies. Using a straightforward Web-based GUI, admins create a hierarchy of profiles, with each policy comprising one or more profiles plus the defined outcome for compliant, partially compliant, and noncompliant systems. Sophos allows policies to be run in report-only, remediate, or enforcement mode. This flexibility is especially useful during the introduction of new policies into the system, and provides for a transition as you determine the compliance of the end points in your environment.
You can create profiles for the operating system (at least one of which is required for every policy), applications (including both security components such as anti-virus as well as user applications such as Internet Explorer), and patches for each of them, and assemble them into policies that outline the required OS patch level, anti-virus application and signature currency, and firewall application and settings. The policy definitions also include the resulting access available to the end point and any alerting necessary. In addition, you specify how frequently the agent on each end point will check for updates to the policy, assess and reassess the host system for compliance, and communicate with the reporting system.
This combination of pre- and post-access awareness allows the end-point agent to adjust to dynamic changes in policies as well as to changes in the host system’s compliance over time. You can also create profiles for custom applications, so if you require specific configurations of custom applications Sophos will allow you to alert and report on those characteristics.
Policy creation and modification is the most complex aspect of policy-based management. Current systems tend to provide detailed and therefore complex views of policies. This is the area ripest for significant improvement in manageability and a breakthrough in human interface design. The inclusion of one-button policies for typical requirements would be a good start.
Agent’s-eye view
As I’ve emphasized in previous reviews, the reporting subsystem of a policy-based network is critical. It is the primary avenue for understanding the current state of your end points and infrastructure, and a key to the ongoing management of the entire network. The Sophos NAC Advanced system includes a comprehensive reporting system that provides both at-a-glance and in-depth reports for the knowledge that the system holds, such as overall compliance status and granular compliance reports based on application, policy, and assessment details.
The reporting system is effective, but it relies exclusively on information provided by the agents, so it has limited visibility into network activity as a component of the reports. By integrating Sophos NAC Advanced with an IDS/IPS, Sophos could extend the reach in an important direction, enabling identification of zero-day events and unexpected network activity to trigger alerting, quarantine, and administrator action. After such a discovery, hooks into an IDS/IPS could also be used to trigger a rescan by all agents to determine characteristics of the impacted systems.
Sophos has focused on providing a system that integrates with a broad range of Windows systems and an even broader range of network elements. The solution provides assessment and remediation for non-Sophos subsystems such as third-party anti-virus agents and other security components, and it integrates into standards-based environments such as 802.1x as well as more proprietary environments such as Cisco NAC.
Sophos NAC Advanced is a solid approach to protecting Windows systems in an enterprise environment. It’s a good fit for organizations concerned mainly with the security status of Windows end points. With the growth of both Mac OS X and Linux in the enterprise, its current lack of support for these platforms may be an issue for those seeking to install policy-based networking. In addition, the product’s focus on end points without engaging network components will leave at least some information unassessed in the process of applying and enforcing policy. Organizations aiming to gain granular control over both hosts and visibility into network traffic will need to look at integrating Sophos with network-based control systems or more network-oriented alternatives such as Cisco NAC.
