Certified: The Security+ Prepcast

In this episode, we explore one of the most overlooked yet critically important areas in cybersecurity—hardening embedded systems and Internet of Things devices. These technologies are everywhere, from smart thermostats and wearable devices to industrial control panels and medical equipment. While they add convenience and innovation, they also increase the complexity of securing modern networks. Unlike traditional computers, embedded systems and Internet of Things devices often have limited resources, long life cycles, and few built-in security features. That makes them attractive targets for attackers—and challenging for defenders.
Let’s begin by talking about embedded systems and real-time operating systems. An embedded system is a specialized computing system that performs a specific function within a larger device. Think of the control panel on a microwave or the navigation system in a car. These systems often run on a real-time operating system, which is designed to process tasks within a strict timeframe. That real-time requirement creates unique security challenges. You cannot afford delays caused by antivirus scanning or software updates that require reboots. Security measures must be lightweight, predictable, and fail-safe.
One of the most effective ways to secure embedded systems is to start at the beginning—during development. Secure boot is a key strategy. This process ensures that the system only loads firmware and software that have been digitally signed and verified. Secure boot acts like a gatekeeper. If unauthorized code tries to execute, the system halts the boot process. This protects against low-level attacks such as bootkits and malicious firmware injections. Secure boot is especially important for systems that operate unattended or in remote locations.
Another development-stage defense is firmware signing. This means every software update or firmware image is signed using cryptographic keys. When the device receives an update, it checks the signature to make sure the code came from a trusted source and has not been tampered with. This prevents attackers from installing rogue firmware or exploiting the update process to gain control of the device. In many cases, firmware signing also enables rollback protection, which blocks older, vulnerable firmware from being reinstalled.
Developers must also take care to remove debugging interfaces and test credentials before shipping devices. These features are often used during development and testing, but they represent major vulnerabilities if left in production. Unfortunately, many devices on the market today still ship with hidden administrative access or undocumented backdoors. This makes it easy for attackers to compromise them once they are deployed.
The challenge with embedded systems is that they often live for a long time and cannot be easily updated. A smart appliance or industrial controller may stay in service for ten years or more. Some systems may not even have the hardware capacity to support encryption, strong authentication, or modern update mechanisms. In these cases, network-level protections become even more important. Segmentation, access controls, and intrusion detection systems must be used to limit exposure and monitor for abuse. These systems cannot be treated as set-it-and-forget-it technology. They must be monitored and integrated into the larger security strategy.
Now let’s turn to Internet of Things devices. These are embedded systems that connect to networks, gather or transmit data, and sometimes interact with physical environments. Internet of Things devices include everything from smart light bulbs to factory sensors to medical monitors. The explosion of Internet of Things technology has created a massive attack surface, much of it unregulated and poorly secured. Many Internet of Things devices come with default usernames and passwords, hardcoded into the firmware. If these credentials are not changed, attackers can easily gain control using publicly available lists.
The first step in hardening Internet of Things devices is to change all default credentials immediately upon setup. This should be part of the initial configuration checklist for any device, regardless of whether it is for home or enterprise use. In environments with large numbers of devices, centralized identity management may be used to assign unique credentials or digital certificates to each unit. Multifactor authentication is rarely supported on Internet of Things devices themselves, but it can often be applied at the management interface to reduce the risk of unauthorized changes.
Another critical hardening step is ensuring that the device receives regular updates. Internet of Things manufacturers should provide a way to patch vulnerabilities through over-the-air updates or manual downloads. Devices that do not receive updates quickly become liabilities. When selecting Internet of Things devices, choose vendors who offer transparent support policies and a proven history of delivering timely security patches. Organizations should inventory all Internet of Things devices, track their firmware versions, and schedule periodic reviews to identify outdated or unsupported units.
For devices that cannot be updated—whether due to hardware limitations or vendor abandonment—network controls must step in. Place these devices on isolated subnets, limit their communication to only essential destinations, and monitor traffic for signs of compromise. For example, if a smart sensor designed to report temperature data suddenly starts sending large amounts of data to an unknown destination, it may be compromised. Firewalls, intrusion detection systems, and logging tools can all help detect and block this kind of behavior.
Practical hardening examples vary depending on the setting. In a home environment, Internet of Things devices should be placed on a separate Wi-Fi network from personal computers. Most modern routers support this feature, often labeled as a guest network. This separation ensures that even if an Internet of Things device is compromised, it cannot easily access sensitive personal data stored on other devices. Users should also disable features that are not needed, such as voice control or remote access, and keep a close eye on the device's permissions within any connected apps.
In an industrial context, Internet of Things hardening becomes more complex. Here, devices often control critical processes such as temperature, flow rate, or pressure. These systems may interface with supervisory control software and require real-time reliability. Hardening begins with procurement. Organizations must choose vendors that support secure protocols, provide signed firmware, and offer tools for device authentication. Once installed, devices should be placed in network zones with tightly controlled access and detailed logging. Communication should be restricted using firewalls and allow lists, ensuring that each device can only talk to approved systems. In high-risk environments, some organizations even use deception technology to lure attackers away from real assets and detect threats early.
A real-world example of successful Internet of Things hardening occurred in a smart building that used hundreds of connected thermostats and occupancy sensors. The devices were all configured with unique credentials, limited to communicating with a central controller over an encrypted channel. A firewall restricted access to that controller, and monitoring software logged every interaction. During a routine audit, the team detected an unusual login attempt from outside the approved network range. Because the system was properly hardened and logged, the attempt was blocked and investigated before damage could occur.
To review, embedded systems and Internet of Things devices present unique security challenges due to their limited resources, long service lives, and often overlooked vulnerabilities. Hardening these devices requires a combination of secure development practices, strict configuration management, and network-level protections. Whether it is verifying firmware signatures, changing default passwords, or isolating vulnerable devices, every step helps reduce the overall risk.
When studying for the Security Plus exam, focus on understanding the differences between traditional systems and embedded or Internet of Things devices. You may see scenario questions that ask you to identify which hardening step is appropriate based on the device type and environment. Be ready to explain terms like secure boot, firmware signing, and over-the-air updates. Know why Internet of Things misconfigurations are common and what steps can prevent them. And be prepared to recommend realistic mitigation strategies when software updates are not an option.
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