The Internet of Things creates one of the largest cybersecurity challenges in modern computing because it connects billions of devices that were never designed with security as a priority. By the end of 2025, an estimated 21.1 billion IoT devices will be connected worldwide, and in the average enterprise network, IoT devices already account for more than 30 percent of all connected endpoints. Each one of those devices is a potential entry point for attackers.
Why IoT Devices Expand the Attack Surface
Every device connected to a network is a door that someone can try to open. Traditional networks had a manageable number of doors: computers, servers, phones. IoT has added thermostats, security cameras, medical monitors, factory sensors, smart speakers, and thousands of other device types, each running its own software and connecting to the internet in its own way. Many of these devices lack encryption and have unprotected access, which means each one widens the total attack surface an organization or household has to defend.
The problem compounds quickly. A single unsecured device on a corporate network represents a potential way in for an attacker who can then move laterally to more valuable systems. An unmonitored smart sensor in a warehouse can become a stepping stone to a company’s financial databases. The sheer volume of devices makes it difficult for security teams to even know what’s connected, let alone protect everything.
The Most Common IoT Vulnerabilities
IoT devices tend to share a predictable set of security weaknesses. The most exploited is simple: weak, guessable, or hardcoded passwords. Many devices ship with default credentials like “admin/admin” that users never change, or worse, that can’t be changed because they’re baked into the device’s software. Attackers don’t need sophisticated tools to exploit this. They just try a list of common defaults.
Beyond passwords, the most frequent vulnerabilities include:
- Insecure network services: Many devices run unnecessary services that are exposed directly to the internet, allowing remote access that was never intended.
- Unprotected data interfaces: The web dashboards, mobile apps, and cloud connections that control IoT devices often lack proper encryption or authentication, making it possible to intercept or manipulate data in transit.
- Insufficient privacy protection: Personal information stored on devices or in their connected ecosystems is often handled without adequate safeguards, leaving sensitive data exposed.
- No device management: Once deployed, many IoT devices have no system for monitoring, updating, or securely retiring them. They sit on networks for years without a single security patch.
How Attackers Actually Exploit IoT Devices
The most notorious example of IoT exploitation is the Mirai botnet, which the U.S. Cybersecurity and Infrastructure Security Agency (CISA) flagged as a major threat. Mirai worked by continuously scanning the internet for vulnerable IoT devices, then attempting to log in using a list of just 62 common default usernames and passwords. That short list was enough to compromise hundreds of thousands of devices, including cameras, routers, and digital video recorders.
Once infected, the devices weren’t damaged or wiped. They were quietly enrolled into a massive network of compromised machines, a botnet, which was then used to flood websites with so much traffic that they went offline. This type of attack, called a distributed denial-of-service (DDoS) attack, took down major websites in 2016. Variations of the Mirai malware later evolved to exploit specific software vulnerabilities in broadband routers, scanning for weaknesses in their remote management protocols.
The pattern is consistent across IoT-focused malware: find devices with default credentials or known software flaws, take control quietly, and use them as tools for larger attacks. The device owner often has no idea anything is wrong.
What IoT Devices Actually Collect
The privacy dimension of IoT cybersecurity is significant. Connected devices collect far more personal data than most people realize. Researchers categorize the identity information gathered by IoT devices into four types: things you know (your name, address, account details), things you have (credit card numbers, ID numbers), things you are (fingerprints, facial features, voice patterns), and things you do (where you go, when you’re home, your daily routines).
Smart home devices can build detailed profiles of your behavior patterns, health data, and physical location over time. When these devices are compromised, the stolen data goes well beyond a leaked email address. It can include geolocation history, biometric information, and health records. Mobile apps that control IoT devices are particularly prone to unauthorized access to sensitive data elements like personal health information.
Why IoT Devices Are So Hard to Secure
The difficulty of securing IoT devices comes down to how they’re built and how they’re sold. Most IoT hardware is designed to be cheap, low-power, and single-purpose. That means limited memory, minimal storage, and just enough processing power to do one job. There’s often no room left over for encryption, intrusion detection, or other security tools that run in the background on a laptop or smartphone.
Patching is where the problem becomes most visible. Many devices simply cannot be updated after they leave the factory. Their hardware wasn’t designed to support it, or the manufacturer never built an update mechanism. Even when over-the-air updates are technically possible, device makers are generally reluctant to provide ongoing security patching as a maintenance service. The economics don’t support it: selling a $30 sensor doesn’t generate enough revenue to fund years of software updates.
Location adds another layer of difficulty. IoT devices are often deployed in places where manual updates aren’t practical, such as sensors spread across a factory floor, agricultural fields, or remote infrastructure. Updating them requires over-the-air mechanisms, which themselves need to be secured with proper authentication. Many devices in remote environments are effectively set-and-forget, running the same software they shipped with for their entire lifespan, vulnerabilities and all.
Risks to Critical Infrastructure and Healthcare
The stakes rise dramatically when IoT devices are embedded in systems that affect physical safety. In industrial settings, compromised connected devices can lead to data corruption, stolen intellectual property, or actual physical consequences like disrupted power grids and halted manufacturing lines. CISA maintains a dedicated program for industrial control system security, specifically because cyberattacks on these systems can cause real-world damage.
Connected medical devices present some of the most alarming scenarios. Devices like smart pacemakers, insulin pumps, and glucose monitors can be targeted by attackers to steal medical records, disable the device, or use it as an entry point into hospital networks. These devices operate in life-critical contexts where even brief disruptions can endanger patients. Security researchers have rated certain tampering attack scenarios against medical devices at the highest severity level because of their potential for life-threatening consequences, even though the attacks themselves require only readily available tools.
Edge Computing Creates New Targets
Many IoT networks now use edge computing, where data is processed on local servers close to the devices instead of being sent to a distant cloud data center. This reduces latency and bandwidth costs, but it creates a new class of security targets. Edge servers continuously collect data from IoT devices for processing and storage, making them attractive to attackers looking to steal sensitive information in one place.
A compromised edge device can act as a gateway into the broader IoT network. Because edge servers sit between IoT devices and cloud infrastructure, an attacker who gains access to one can potentially reach everything connected to it. Many edge devices share the same hardware limitations as the IoT devices they serve: constrained processing power, limited memory, and difficulty running robust security software. They also frequently rely on third-party components and firmware, which means a vulnerability introduced during manufacturing can create a backdoor before the device is even deployed.
What Makes IoT Security Different
Cybersecurity for traditional computers relies on a few core assumptions: devices have enough power to run security software, they receive regular updates, and someone is actively monitoring them. IoT breaks all three. The devices are too small and cheap for robust security tools, manufacturers rarely commit to long-term support, and the sheer number of devices makes monitoring every one impractical.
The result is a security landscape where the weakest links are multiplying faster than defenses can keep up. Network visibility is the foundation of any response. If you don’t know what’s connected to your network, you can’t protect it. For home users, this means periodically checking what devices are connected to your router, changing default passwords on every device, and replacing devices that no longer receive updates. For organizations, it means investing in tools that can automatically discover and classify every IoT device on the network, segment them away from sensitive systems, and flag unusual behavior. The core challenge remains the same at every scale: billions of small, limited devices are now part of the internet, and each one needs to be treated as a potential vulnerability.