A smart city runs on always-on connectivity with traffic signals, utilities, and public services that rely on sensors and data to stay responsive. The catch is that every connected device, app and vendor integration adds another doorway into the environment, creating a large attack surface that’s always changing.
Unlike a typical enterprise network, smart city systems use legacy infrastructure with new Internet of Things (IoT) and operational technology, often spread across departments and third parties. That mix makes it harder to keep security consistent and respond quickly enough to prevent breaches.
What Is a Smart City Attack Surface?
An attack surface is the sum of all potential entry points an attacker could exploit. These areas can include devices, software, accounts, networks, APIs and even misconfigured cloud services. In a smart city, that “front door” is only one system. It’s everything from traffic management platforms and public Wi-Fi to IoT sensors, cameras, connected building systems and the vendors that maintain them.
Smart cities differ due to the volume and variety of connected technologies. For context, IoT analytics estimated that there were 18.5 billion connected IoT devices in 2024, with growth continuing at 14% in 2025. As a result, cities are operating in a world where connected endpoints are ubiquitous.
Add in digital and physical convergence, and it becomes much harder to track what’s exposed at any given moment.
Top Challenges of Managing the Attack Surface
Managing a smart city’s attack surface is more than a matter of “more devices, more risk” — it’s the reality that these environments are distributed, constantly shifting, and often shared across departments and third parties. Before reducing exposure, it helps to understand the specific challenges that make smart city security difficult.
1. Massive Scale and Diversity
Smart cities operate on a scale that most traditional organizations never encounter. Thousands or even millions of connected endpoints from different vendors must coexist, often running on various standards and life cycles. Legacy infrastructure — such as traffic control systems or utility hardware — frequently operates alongside newer IoT platforms, making it difficult to achieve centralized visibility and consistent security controls. As cities expand, keeping an accurate, up-to-date inventory of what’s connected becomes a challenge in itself.
2. Physical-Digital Convergence
In smart cities, cyber risk grows beyond data breaches. A compromised system can directly affect physical operations, leading to traffic disruptions, power outages or water system failures. This convergence raises the stakes for defenders, since an attack may impact public safety or critical services. Incident response also becomes more complex when teams must coordinate with operational and emergency services.
3. Complex Supply Chains and Third-Party Risk
Cities heavily depend on outside vendors to deploy and manage their smart infrastructure. Each provider brings its own security practices, update schedules and risk posture. According to a 2024 ENISA threat landscape report, supply chain attacks remain one of the fastest-growing threat vectors across critical infrastructure sectors, so third-party weaknesses can quickly become citywide problems. Enforcing consistent security standards across vendors is often easier said than done.
4. Shadow IT and Unmanaged Assets
Individual departments may deploy smart solutions independently, sometimes without informing central IT teams. These unmanaged assets can create blind spots, leaving systems unmonitored and unpatched. Over time, shadow IT significantly expands the attack surface without anyone fully realizing the extent of its impact.
5. Data Privacy and Governance
Smart cities collect enormous amounts of sensitive information, making privacy and governance a major concern. This challenge is then amplified by urban population growth. According to research, over 50% of the global population already lives in cities and is likely to exceed 66% by 2050. Securing and governing the personal data of billions of urban residents while meeting regulatory expectations is a monumental and ongoing task.
How to Secure a Smart City
Securing a smart city starts with accepting that the attack surface will never be fully static. With that in mind, these strategies focus on improving visibility, reducing risk and building resilience across complex, interconnected systems.
Gain Total Visibility With Attack Surface Mapping
Protecting what you can’t see is impossible. Secure a smart city by building a complete, continuously updated inventory of all connected assets. Attack surface mapping helps security teams identify exposed systems and forgotten assets before attackers do. In an environment that’s always changing, visibility has to be ongoing.
Adopt a Zero-Trust Mindset
Smart cities should assume that no user, device or application is automatically trustworthy. A zero-trust approach enforces strict identity verification and access controls at every connection point, regardless of whether the traffic originates from within or outside the network. This limits lateral movement if a system is compromised and helps contain incidents before they spread across departments or critical services.
Foster Public-Private Partnerships
Cities do have a way to tackle cybersecurity with partnerships. They should collaborate with cybersecurity vendors, utilities and even neighboring municipalities. Such alliances allow teams to share threat intelligence, lessons learned and best practices. They can also improve detection capabilities and help cities respond faster to emerging threats that may affect shared infrastructure or technologies.
Conduct Regular Audits and Penetration Testing
Proactive testing is essential for uncovering weaknesses before attackers exploit them. Regular security audits and penetration tests help identify vulnerabilities across networks, devices and applications, including those introduced by new deployments or updates. Testing for smart cities should account for both IT and operational technology to reflect real-world risk.
Prioritize Security in Procurement
Security should be built in before technology is ever deployed. Cities can reduce risk by requiring vendors to meet clear cybersecurity standards during the procurement and contract negotiation process. This approach is mirrored at the national level. For example, the U.S. government’s IoT Cybersecurity Improvement Act of 2020 established minimum security requirements for IoT devices used by federal agencies. By setting similar expectations up front, cities can prevent insecure technology from expanding their attack surface in the first place.
Building a Safer Smart City Attack Surface
Smart cities deliver real benefits, but the same connectivity that makes them efficient also creates more opportunities for attackers. By understanding where risk concentrates, city leaders can make more informed security decisions without hindering innovation.
