Organizations face an ever-expanding attack surface and a host of cyberthreats. Yet, most organizations have limited resources and lack effective solutions to fully understand and address their network security risks. This forces security leaders to find more efficient ways to analyze network security, identify risks and prioritize remediation. This is where reachability analysis and risk-based prioritization become crucial tools for optimizing cybersecurity strategies. 

Understanding reachability in the context of corporate risk is increasingly important for enterprises, as it can significantly influence their risk management strategies. To protect critical data and infrastructure from unauthorized access, organizations often implement firewalls and multiple layers of security. However, business objectives and the complexity of the security architecture necessitate that some of these assets are more reachable than others. This access hierarchy is known as reachability.  

Understanding Reachability 

Reachability refers to the accessibility vulnerabilities within a network. In traditional vulnerability management, the security team scans every port on every server or network device to identify vulnerabilities. This produces lists of thousands of potential issues ‒ daily. However, only a small percentage of these vulnerabilities are ever actually exploited.  

The challenge for the security team is determining which vulnerabilities pose the greatest risks to prioritize where they spend their time and limited resources. Filtering vulnerabilities by severity provides some help, but typically, the number of critical and high–severity vulnerabilities is still so high that it‘s challenging to determine a starting point. This is where the notion of “possibly affected devices” becomes pertinent.  

Some vulnerabilities can impact a device only if specific configurations are present, a specific feature is turned on, or they are deployed in a specific manner. Also, many vulnerable devices and applications are protected within the infrastructure by firewalls, application gateways and other security controls. By analyzing reachability, security teams can identify and address the true vulnerabilities that pose the greatest risk rather than chasing every possible weakness. 

Reachability-Driven Threat Exposure 

Rather than treating all vulnerabilities as equal, reachability-driven threat exposure takes into account the context of each vulnerability to determine what level of threat it presents. Key factors include: 

• The importance and criticality of the affected asset 

• Its location within the network architecture  

• Existing security controls and layers of protection 

• Potential attack paths to reach the vulnerable system 

By incorporating this contextual awareness, organizations can move beyond basic vulnerability management to true threat assessment. This allows for more informed prioritization of remediation efforts. 

Implementing Reachability Analysis 

Despite the benefits, most organizations lack the tools and processes to analyze reachability across their infrastructure. Most are limited to a few common approaches with known downsides. External vulnerability scanners provide limited visibility into internal networks. Penetration testing typically focuses on external attack surfaces. And, manual analysis is incredibly time-consuming and error-prone.  

Achieving comprehensive reachability analysis is challenging, especially for large environments with tens of thousands of assets, as it’s difficult to compute all the states that a system might reach during operation. Also, as networks and systems are dynamic, with routers, firewalls and other components changing, it’s nearly impossible to analyze all the potential paths packets can traverse. Other challenges include gaps in visibility, cost and changing network configurations. And these challenges become exponentially more complex in hybrid, multi-cloud environments.  

Emerging Solutions 

To address these challenges, organizations should leverage network digital twin technology. A sophisticated network digital twin collects L2-L7 state and configuration data across all network devices (load balancers, routers, firewalls and switches). This data is then used to create an accurate topology (on-prem and multi-cloud), calculate all possible paths within the network, analyze detailed behavioral information and make network configuration and behavior searchable and verifiable. 

Creating an accurate digital replica of an organization’s network infrastructure allows for automated analysis of potential attack paths and reachability between assets. This comprehensive visibility is needed for effective threat exposure management, revealing the full topology and their relationships and potential vulnerabilities in context. By combining this network-wide visibility with vulnerability data, organizations can leverage digital twin technology to achieve a true reachability-driven approach to threat assessment and prioritization. 

Benefits of Reachability-Based Prioritization 

Implementing reachability analysis offers several key benefits: 

• Efficiency –  Resources are dedicated to addressing the most critical vulnerabilities, not analyzing mountains of data. 

• Reduced alert fatigue – By prioritizing vulnerabilities, the security can focus on high-priority threats. 

• Improved decision-making – Understanding reachability allows for a more informed remediation response. 

• Optimized processes – Governance provides a more accurate picture of actual risk. 

Overall, reachability-based prioritization enables organizations to identify and address the most pressing vulnerabilities, narrowing the focus and resources required to improve the network security posture. 

Conclusion 

Reachability-driven threat exposure offers an effective way to understand what vulnerabilities exist and how accessible and exploitable they are to attackers. This enables organizations to make smarter, more informed decisions about how to protect their network. Technologies like a network digital twin are making comprehensive reachability analysis possible. As the threat landscape continues to evolve, incorporating reachability into risk assessment and prioritization processes will be crucial for organizations aiming to stay ahead of cyberthreats.