IoT adoption across enterprise environments has grown rapidly, and with it, the attack surface facing security teams.
From connected medical devices monitoring patient vitals in real time, to industrial sensors managing critical infrastructure, to smart building systems controlling access, lighting, and HVAC, the operational benefits are significant and increasingly difficult to ignore.
However, there is a more sinister underlying reality to IoT devices that goes largely unaddressed: many were built for convenience rather than security.
Because of this, connected devices rapidly expand attack surfaces, expose weak credentials, and create easy entry points for hackers into wider networks, only increasing the amount of potential damage done.
This article will provide a practical guide to the most common risks and the controls that reduce IoT vulnerabilities, including how penetration testing is an essential component of any secure IoT programme.
What are IoT Vulnerabilities?
IoT vulnerabilities are weaknesses in connected devices, their firmware, communication channels, APIs, or supporting platforms.
These issues can stem from:
- Poor configuration and open ports
- Insecure design
- Outdated software
- Weak authentication
- Limited update support
IoT risk goes beyond the device to what it connects to. Compromised devices can be entry points for attackers to access networks, data, or critical systems. The more devices connected, the worse the breach can be. Securing IoT means protecting devices, their networks, communication channels, and connected platforms together to prevent security challenges from arising.
The Impact of IoT Vulnerabilities
IoT security challenges, in turn, introduce a wide array of potential impacts to any business.
| Impact | Description |
|---|---|
| Data Exposure | Compromised IoT devices can leak sensitive business and customer data, including payment information, personal records, and operational data, often without detection until significant damage has already occurred. |
| Remote Device Takeover | Attackers can seize control of IoT endpoints remotely, manipulating device behaviour, disabling security controls, or using compromised devices as a foothold for deeper network infiltration. |
| Lateral Movement into Internal Networks | Poorly segmented IoT devices provide attackers with a pivot point to move laterally across internal networks, escalating privileges and reaching high-value systems such as POS terminals, databases, and corporate infrastructure. |
| Service Disruption | Malicious actors can exploit IoT vulnerabilities to interrupt business operations, disabling critical systems and causing severe disruptions to service delivery, payment processing, and day-to-day operational efficiency. |
| Safety or Operational Risk in Physical Environments | In environments where IoT controls physical infrastructure, such as access controls, HVAC, or industrial equipment, a breach can create direct safety risks for staff and customers, alongside significant operational and regulatory consequences. |
The Most Common IoT Vulnerabilities
To enforce best IoT security practices within your organisation, it’s important to first understand what causes vulnerabilities and leads to an initial breach in IoT environments.
Weak or default credentials
Many IoT devices ship with default usernames and weak passwords that organisations neglect to change, making it trivial for attackers to scan for exposed devices and gain immediate, unauthorised access.
Unpatched firmware and software
IoT vendors are often slow to release updates, and organisations are slower still to deploy them, leaving known vulnerabilities unaddressed and providing attackers with a reliable and well-documented path to exploitation.
Insecure network exposure
IoT devices are often placed on flat, unsegmented networks or exposed to the internet without justification, making it straightforward for attackers to move laterally between devices or pivot directly into core business systems.
Weak authentication and access control
Many IoT devices rely on weak authentication mechanisms, such as default credentials that are never changed, or basic API protections that offer little resistance to a determined attacker. Without robust access controls and proper privilege management, attackers can manipulate device settings, intercept sensitive data, or pivot deeper into the network.
In operational technology environments, where a single compromised sensor or controller can affect physical processes, the consequences of poor access control extend well beyond a conventional data breach.
Insecure APIs and communication channels
Unprotected APIs, weak encryption, or poor certificate handling can expose telemetry, commands, or credentials. This is especially important for mobile apps, dashboards, and cloud-connected device platforms.
Lack of secure update mechanisms
If devices cannot be securely updated, vulnerabilities remain for years. This is a major issue for long-lived devices in industrial or commercial environments, as outdated firmware and software vulnerabilities can be exploited by attackers to gain unauthorised access, disrupt operations, or manipulate device behaviour.
Excessive data collection and poor privacy controls
Many IoT devices collect far more data than their core function actually requires. When this excessive data collection is paired with poor privacy controls, weak encryption, or unclear retention policies, the compliance risks for businesses grow quickly.
Under frameworks such as GDPR, organisations are accountable for every piece of personal data their systems process, whether it was intentionally gathered or not.
Physical tampering and local access
IoT devices that are deployed in public locations like factory floors or shared office spaces can be physically tampered with by anyone who can access them. Attackers can reset devices to extract stored credentials, modify firmware, or even clone the device entirely.
Physical access gives attackers an often overlooked route into your broader network infrastructure, and is not a vulnerability to be ignored.
How attackers exploit IoT vulnerabilities
Hackers have a variety of methods that they can utilise to target IoT devices and gain access to sensitive data. Understanding how IoT vulnerabilities are exploited allows security teams to proactively defend against cyber threats and enforce best practices.
The most common attack paths security teams should be aware of include:
- Scanning for exposed devices
- Guessing or cracking default credentials
- Exploiting outdated firmware
- Pivoting from an IoT device into a corporate network
- Using compromised devices to access cloud dashboards or APIs
Beware of Botnets: When Your Own Devices Become Weapons
Compromised IoT devices are frequently recruited into botnets, where attackers use them to carry out large-scale attacks such as distributed denial-of-service campaigns, credential stuffing, or spam operations.
Because IoT devices typically run continuously with minimal monitoring, they can be used this way for extended periods without anyone noticing, placing strain on your network and implicating your organisation in malicious activity originating from your own infrastructure.
In most instances, IoT compromise is a stepping stone, not the end goal.
Attackers can manipulate access to vulnerable IoT devices to move deeper into an organisation’s network, using them as a foundation to reach higher-value targets such as financial systems, customer information, and critical infrastructure.
How to Secure Against IoT Vulnerabilities
Securing against IoT vulnerabilities effectively goes beyond just one or two reactive steps. In fact, it is a combination of proactive security techniques and continuous monitoring that provides businesses with the best defences against IoT security risks. Here are some essential measures to prioritise to safeguard your business:
Change default login credentials immediately
- Require unique, strong passwords for every device and admin account.
- Ensure default device credentials provided during setup are changed before deployment.
- Where possible, use MFA for dashboards and management portals. Strong authentication procedures are key to protecting user accounts.
Keep firmware and software updated
- Maintain a patching process for devices, gateways, and companion applications.
- Track vendor support lifecycles so end-of-life devices are removed or replaced.
Segment IoT devices from critical systems
- Place devices on separate networks or VLANs and restrict what they can access.
- Apply the principle of least privilege to traffic flows, restricting access to anyone who does not strictly need it.
Secure APIs and remote access
- Use authentication, encryption, key management, and access logging for all device platforms.
- Review exposed endpoints regularly.
Encrypt data in transit and at rest
- Protect telemetry, credentials, and sensitive device data using strong encryption
- Avoid sending sensitive information over untrusted channels
Disable unnecessary services and features
- Reduce the attack surface by turning off unused ports, services, and remote functions.
- The fewer exposed features, the fewer ways in.
Monitor for unusual behaviour
- Look for strange traffic patterns, unknown devices, suspicious activity, anomalous behaviour, configuration changes, and unexpected outbound connections.
- Detection matters, because many IoT devices are difficult to harden completely.
- Automated scanners can support real-time monitoring of your IoT environments, alerting you to any unusual activity and empowering you to respond to potential threats more effectively.
Build security into procurement
- Choose vendors that offer secure-by-design devices, automatic update support, and clear documentation. Regularly implement new software patches and firmware updates.
- Remember: security should be a buying requirement, not an afterthought.
The Role of Penetration Testing in IoT Security
By simulating real-world cyberattacks, IoT pentesting helps verify whether vulnerabilities in your IoT devices are exploitable and brings to light any prevalent security issues that require remediation.
Penetration testing goes beyond simply detecting anomalous behaviour to investigate a range of issues across the device, covering your IoT firmware, app, API, network, and cloud layers.
When to invest in pentesting?
Knowing when to invest in IoT penetration testing is just as important as the testing itself. Security teams should prioritise an assessment when rolling out a new IoT deployment, after a major firmware or cloud platform update, ahead of a compliance audit, or following an incident or suspicious device behaviour.
Each of these moments represents a point where your attack surface has changed, or your existing controls aren’t verified.
Treating these as routine processes, rather than reactive afterthoughts, is what separates a managed IoT security posture from an exposed one.
How Can OnSecurity’s Pentesting Help?
Web Applications
Web application testing identifies vulnerabilities such as SQL injection, broken authentication, and cross-site scripting before attackers can exploit them, helping organisations secure customer-facing and internal platforms.
Mobile Apps
Mobile app pentesting uncovers insecure data storage, weak authentication, and unprotected API endpoints that could expose sensitive customer or payment data to unauthorised access in your IoT applications.
Cloud Environments
Cloud security testing assesses misconfigurations, overly permissive access controls, and exposed storage buckets, giving organisations a clear picture of their cloud risk exposure and potential sources of data breaches.
Network Infrastructure
Network penetration testing identifies weaknesses in firewalls, routers, and VPN gateways that could allow attackers to gain direct access to internal systems and sensitive data.
External Attack Surface
External attack surface assessments map all internet-facing assets and public networks, identifying forgotten infrastructure, exposed subdomains, and unmonitored entry points before attackers can exploit them.
Uphold the highest security standards and protect your IoT devices today with OnSecurity’s platform-led penetration testing services.
