Pen Testing IoT: Inside The Mind of an Ethical Hacker

We have spent time discussing vulnerabilities (Check it out here if you missed it) in our smart devices, such as unencrypted communication, default credentials, and outdated firmware. However, this raises an important question: how do we even find these vulnerabilities in the first place? Smart devices don’t raise their hands and admit they're insecure, so how does an attacker know which devices to compromise? The discovery process isn’t guesswork. It’s methodical, strategic, and very much hands-on. This process is known as penetration testing.

Penetration testing, also commonly referred to as ethical hacking or red teaming, is a method used by security professionals to simulate attacks and discover flaws before real attackers do. It does not always have to be a computer system, it could just as easily be a secure building. The core idea remains the same: to break in, not to cause harm, but to reveal how it could happen so that it can be prevented. In digital systems, penetration testing involves five key stages: information gathering, footprinting and scanning, vulnerability assessment, exploitation, and post-exploitation. Let's go through the processes.

The lifecycle begins with Information gathering (also known as reconnaissance), where testers gather as much publicly available information as possible about the target, often without directly interacting with it. For IoT, this may include reviewing vendor documentation or analyzing firmware versions available on the manufacturer’s website. The goal is to understand what the device is, what it’s running, and what potential weaknesses it might have before ever sending a single packet its way (a packet is a small chunk of data sent over a network, kind of like a digital envelope).

Next comes footprinting and scanning, which involves actively probing the system to identify what’s open and how it’s structured, to pinpoint vulnerable spots. A tool like Nmap (Network Mapper) is commonly used here to scan for open ports (entry points where devices communicate), the services running on these ports, and the protocols in use. In the case of smart devices, you might uncover HTTP servers or even outdated remote access services, such as Telnet, still sitting open. At this stage, testers often use tools like Wireshark, which capture and analyze the data flowing over the network, helping to spot things like unencrypted traffic that could be intercepted.

In the vulnerability assessment stage, after mapping out the system, pen testers check for known weaknesses that could be exploited. This might include missing encryption, hardcoded credentials, or weak authentication. Automated tools like OpenVAS, Nessus, or Burp Suite can help flag known vulnerabilities here, but sometimes, skilled testers could go manual.

Then comes exploitation, where testers try to break into the system using the vulnerabilities discovered in the previous stage. This could be gaining access through a default password, exploiting a firmware flaw, or abusing an insecure update. In IoT, exploitation could mean intercepting the device’s communication or bringing it to a complete stop. A common tool like Metasploit could come into play here to help automate and organize attacks.

Finally, post-exploitation. This is about understanding what an attacker could do once they’re in. Can they move laterally? Steal data? Brick the device? During this stage, testers evaluate persistence (can access be maintained?), privilege escalation (can higher system control be gained?), and identify further risks that the compromise could lead to. Most importantly, they document every step clearly so the issues can be fixed.

Ideally, penetration testing is not about causing harm; it is about understanding, testing, and strengthening security.

There are three main types of penetration testing approaches, and the choice depends on the amount of information available about the system(s). Let’s dive into them.

- Black box testing: This is the most external and realistic. In this, you go in blind, just like a real attacker would. No insider access, no information, just observation, trial and error testing, and patience to find security flaws (and maybe a little frustration when things don’t crack open right away).

- White box testing: This is full access. It involves having information about everything in the system. This includes source code, internal documentation, credentials, architecture diagram, you name it. White box digs deep, often guaranteeing the entire surface is tested.

- Grey box testing: This is a combination of white box and black box. It offers some internal knowledge and information about the system, but not all, like knowing the operating system running on the system. The remainder of the information is not provided and is meant for identification by the pen tester.

Penetration testing in IoT brings its complications because, unlike standard devices, IoT devices come in all shapes and architectures, run on minimal resources, and often lack documentation. Testing them isn’t just about scanning a network, it’s about understanding how the device works, how it communicates, and where it might break. In a recent controlled test, I looked at a small network of smart home devices. With no inside information (black box style), I found multiple vulnerabilities, exploited weak authentication protocols, unencrypted communication, and uncovered sensitive information such as hardcoded credentials sitting right there in plain sight (Curious how that played out? Check out my earlier article here for the full breakdown!).

Pen-testing isn’t just about the method, it’s also about tools. Common tools like Nmap (Network Mapper), Wireshark, Burp Suite, and Metasploit make it easier to visualize and find openings, and validate whether those openings could be turned into actual entry points. Penetration testing isn’t just about breaking things, it’s about understanding how they can break and fixing the cracks before someone else finds them. In the world of IoT, where smart devices are growing rapidly, without that knowledge, it’s only a matter of time before convenience becomes a liability.

Thanks for reading, and as always, friends, stay smart, stay secure! More soon!