Securing 5G Networks: Addressing Control Plane Challenges

Without question, the additional requirements that the 5G control plane supports will inject additional complexity into security enforcement. Accordingly, this was an area of interest to the sponsors of Heavy Reading’s recently completed 5G Security Market Leadership Study (MLS).

The MLS-based survey we developed with F5 Networks, Fortinet, NetNumber and Palo Alto Networks attracted 103 global respondents and included several questions related to the challenges of control plane security. These questions ranged from assessing service providers’ confidence levels in securing the 5G control plane and use case-specific challenges to determining how they would select 5G control plane security vendors.

Control Plane Security: A Special Area of Focus

The topic of control plane security has been of considerable interest for me for some time. Going back as far as seven years ago, as part of my IP Multimedia Subsystem (IMS) coverage, concerns were already noted in articles related to the potential for 4G IMS-fueled signaling storms. These signaling storm concerns ultimately did come to fruition. Fortunately, however, they were mitigated by the industry adoption of software-based control plane platforms such as Diameter signaling controllers (DSCs) that could scale and seamlessly interwork 2G protocols like SS7 and 4G Diameter-based nodes.

In parallel, there have been increasing concerns about the security of mobile networks due to vulnerabilities with the use of the SS7 and Diameter signaling protocols for the support of mobile roaming. Issues include the risks for both network overload and denial-of-service (DOS) incidents as well as the risks to individual customers of location tracking, eavesdropping, and banking fraud. As a result, the GSM Association (GSMA) recommended its mobile operator members should enhance the protection of their SS7 and Diameter interconnects with the addition of signaling firewalls.

Another control plane concern I had was that even with 4G and the very early days of network functions virtualization (NFV), there was a sense that the control plane was evolving to play a greater role in service orchestration, which injected additional security concerns. I documented this trend in a 2013 Heavy Reading report, “Service-Enabling the Control Plane: The Role of Diameter Signaling in Next-Generation Networks.”

When I caught a first glimpse in 2017 of the 5G next-generation core (NGC) architecture with a fully distributed control plane utilizing protocols such as HTTP/2 to support a service-based architecture (SBA) control plane, it was hard not to think the control plane would once again become an area of concern. An additional concern with 5G is caused by the impact of worldwide digital transformation enabled by massive amounts of sensors, connected cars, health monitors, etc. that will connect to networks. The network actions taken by all these devices will be automated and without human intervention, possibly creating or escalating security incidents.

The study input from the survey respondents validated some of these concerns. Based on the high percentage of “agree” responses, there is little doubt that the 5G control plane will be more problematic to secure on several levels, as illustrated in the figure below. For example, a high number of respondents believe 5G roaming will be more difficult to secure (70%) and more susceptible to fraud (63%). In addition, many respondents believe signaling storms will be more common both in the New Radio (NR) and NGC (65% and 60%).

Thus, security must be able to protect against multiprotocol attacks (68%), which affects the need to deploy distributed signaling firewalls (66%) that play a role in managing topology hiding challenges (61%). Security must also enable improvements in responses to threat vectors using caller ID (CLI) spoofing and robocalling (65%). Based on this input, the 5G control plane will continue to be a special area of focus in a security context.

Fraud and security vendors: criteria for selection

This shift in application interactions on the control plane and the additional complexity inherent with securing the 5G control plane will also influence the criteria for selecting fraud and security vendors. Two attributes stand out, as illustrated in the figure below. Based on “extremely important” responses, these are programmable rule sets (41%) and multi-tenant use case support (39%). The rule sets are logical on many levels since the application-specific policy is a requirement for 5G services and enforcement must take place on the control plane.

Multi-tenant use case support is important because the reality of the 5G application paradigm is that multi-tenant applications become a mandatory construct when software resources are shared among users. However, specific policies must be applied to various user profiles and slices to meet performance targets, achieve services differentiation, and perhaps most importantly, prevent fraud and security breaches.

Moreover, other attributes that complement these two vendor selection attributes, such as scale (31%), application programming interface/Representational State Transfer (API/REST) support (29%), and distributed architecture design (29%), are also important when selecting vendors. They provide the necessary level of platform flexibility and programmability to adapt to changes in security service mix. The message from this input is clear: signaling and fraud solutions must be programmable and scalable, multi-tenanted, and API-controllable to meet the real-time needs of distributed architecture configurations and avoid vendor lock-in.—Light Reading

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