Rapid adoption of cloud services by companies of all sizes is enabling many business benefits, most notably improved agility and lower IT infrastructure costs. However, as IT environments become more heterogeneous and geographically distributed in nature, many organizations are seeing their security attack surface multiply exponentially. This challenge is compounded by the accelerating rate of IT infrastructure change as more organizations embrace DevOps-style application deployment approaches and more extensive infrastructure automation.
Longstanding security practices such as system hardening, proactive vulnerability management, strong access controls, and network segmentation continue to play valuable roles in security teams’ attack surface reduction efforts. However, these measures alone are no longer sufficient in hybrid cloud environments for several reasons.
The first is that while these practices remain relevant, they do little to counteract the significant attack surface growth that cloud adoption and new application deployment models like containers are introducing. In addition, it is difficult to implement these practices consistently across a hybrid cloud infrastructure, as they are often tied to a specific on-premises or cloud environment. Lastly, as application deployment models become more distributed and dynamic, it is exposing organizations to greater risk of unsanctioned lateral movement. As the volume of east/west traffic grows, network-based segmentation alone is too coarse to prevent attackers from exploiting open ports and services to expand their attack footprint and find exploitable vulnerabilities.
These realities are leading many security executives and industry experts to embrace micro-segmentation as a strategic priority. Implementing a holistic micro-segmentation approach that includes visualization capabilities and process-level policy controls is the most effective way to reduce attack surface as the cloud transforms IT infrastructure. Moreover, because micro-segmentation is performed at the workload level rather than at the infrastructure level, it can be implemented consistently throughout a hybrid cloud infrastructure and adapt seamlessly as environments change or workloads relocate.
Visualizing the Attack Surface
One of the most beneficial steps that security teams can take to reduce their attack surface is to gain a deeper understanding of how their application infrastructure functions and how it is evolving over time. By understanding the attack surface in detail, security teams can be much more effective at implementing new controls to reduce its size.
Using a micro-segmentation solution to visualize the environment makes it easier for security teams identify any indicators of compromise and assess their current state of potential exposure. This process should include visualizing individual applications (and their dependencies), systems, networks, and flows to clearly define expected behavior and identify areas where additional controls can be applied to reduce attack surface.
Attack Surface Reduction with Micro-Segmentation
As more application workloads shift to public cloud and hybrid-cloud architectures, one area where existing attack surface reduction efforts often fall short is lateral movement detection and prevention. More distributed application architectures are significantly increasing the volume of “east/west” traffic in many data center and cloud environments. While much of this traffic is legitimate, trusted assets that are capable of communicating broadly within these environments are attractive targets for attackers. They are also much more accessible as the traditional concept of a network perimeter becomes less relevant.
When an asset is compromised, the first step that attackers often take is to probe and profile the environment around the compromised asset, seek out higher-value targets, and attempt to blend lateral movement in with legitimate application and network activity.
Micro-segmentation solutions can help defend against this type of attack by giving security teams the ability to create granular policies that:
Enforce general corporate security policies and best practices throughout the infrastructure
These measures and others like them slow or block attackers’ efforts to move laterally. When implemented effectively, micro-segmentation applies the principle of least privilege more broadly throughout the infrastructure, even as it extends from the data center to one or more cloud platforms.
This focus on preventing lateral movement through in-depth governance of applications and flows reduces the available attack surface even as IT infrastructure grows and diversifies.
Beyond the Network Attack Surface
Successful use of micro-segmentation to reduce attack surface requires both Layer 4 and Layer 7 process-level controls. Process-level control allows security teams to truly align their security policies with specific application logic and regulatory requirements rather than viewing them purely through an infrastructure lens.
This application awareness is a key enabler of the attack surface reduction benefits of micro-segmentation. Granular policies that whitelist very specific process-level flows are much more effective at reducing attack surface than Layer 4 controls, which savvy attackers can circumvent by exploiting systems with trusted IP addresses and/or blending attacks in over allowed ports.
Granular Layer 7 policy controls make it more possible for organizations to achieve a zero-trust architecture where only the application activity and flows represent known sanctioned behavior are allowed to function unimpeded in the trusted environment.
The Importance of a Multi-OS, Multi-Environment Approach
As the transition to hybrid cloud environments accelerates, it is easy for organizations to overlook the extent to which this change magnifies the size of their attack surface. New physical environments, platforms, and application deployment methods create many new areas of potential exposure.
In addition to providing more granular control, another benefit that micro-segmentation provides to organizations seeking to reduce attack surface is that it achieves a unified security model that spans multiple operating systems and deployment environments. When policies are focused on specific process and flows rather than infrastructure components, they can be applied across any mix of on-premises and cloud-hosted resources and even remain consistent when a specific workload moves between the data center and one or more cloud platforms. This is a major advantage over point security products that are tied to a specific environment or platform, as it enables attack surface to be minimized even as the environment becomes larger and more heterogeneous.
When selecting a micro-segmentation platform, it is important to validate that the solution works seamlessly across your entire infrastructure without any environment- or platform-specific dependencies. This includes validation that the level of control is consistent between Windows and Linux and that there is no dependence on built-in operating system firewalls, which do not offer the necessarily flexibility and granularity.
While the transformation to cloud or hybrid-cloud IT infrastructure does have the potential to introduce new security risks, a well-managed micro-segmentation approach that is highly granular, de-coupled from the underlying infrastructure, and application aware can actually reduce the attack surface even more as more infrastructure diversity and complexity is introduced.