A Cybersecurity Weak Link: Linux and IoT

When Linus Torvalds developed a free operating system back in 1991 in his spare time, nobody could have guessed where it would lead.

Linux is not only the backbone of the Internet and the Android operating system, it's also in domestic appliances, motor vehicles, and pretty much anything else that requires a minimal operating system to run dedicated software. The Internet of Things (IoT) is very much powered by Linux.

But when Chrysler announced a recall of 1.4 million vehicles back in 2015 after a pair of hackers demonstrated a remote hijack of a Jeep's digital systems, the risks involved with hacking IoT devices were dramatically illustrated. 

So, what does the rise of Linux and IoT mean for cybersecurity in the enterprise? Let's take a look.

Our Networks Have Changed
Today's defense solutions and products mostly address Windows-based attacks. It's the most prevalent operating system in the enterprise, and the majority of system administrators are tasked with solving the security problems it brings. 

Over time, however, the popularity of Windows in enterprise IT has weakened. A growing number of DevOps and advanced users are choosing Linux for their workstations. In parallel, the internal and external services a typical enterprise offering has moved away from Windows-based devices to Linux: Ubuntu, SUSE, and Red Hat. Linux containers have broad appeal for enterprises because they make it easier to ensure consistency across environments and multiple deployment targets such as physical servers, virtual machines, and private or public clouds. However, many Linux container deployments are focused on performance, which often comes at the expense of security.

Beyond that, every device used in the network is now connected to the same networks where all the most valuable assets reside. What used to be a simple fax machine has now become a server. Our switches and routers are moving into the backbone of our most secure networks, bringing along the potential for cyber breaches as they do so. 

Malware Authors' Heaven
Let's shift our attention from the defender to the attackers, whose strategy often is to use minimal effort for maximum impact. In many cases, keeping things simple proves to be enough. 

If you look at your network from the attacker's perspective, there are enough open doors to penetrate without the hassle of crossing the security mechanisms of the most common operating system. Of course, that doesn't mean you can relax the effort to secure your Windows devices; there are still some severe weaknesses (social engineering anyone?).

Here are a few notable breaches involving IoT or, by extension, Linux-controlled devices: 

1. Compromising a Network by Sending a Fax
Check Point researchers have revealed details of two critical remote code execution (RCE) vulnerabilities they discovered in the communication protocols used in tens of millions of fax machines globally. (A patch is available on HP's support page.)

2. The Mirai Botnet
In October 2016, the largest distributed denial-of-service attack ever was launched on service provider Dyn using an IoT botnet, which led to huge portions of the Internet going down. The Mirai botnet caused infected computers to continually search the Internet for vulnerable IoT devices such as digital cameras and DVRs, and then used known default usernames and passwords to log in and infect them with malware. 

3. 465,000 Abbott Pacemakers Vulnerable to Hacking
In the summer of 2016, the FDA and Homeland Security issued alerts about vulnerabilities in Abbott pacemakers that required a firmware update to close security holes. The unpatched firmware made it possible for an attacker to drain the pacemaker battery or exfiltrate user medical data. (The firmware was updated a year later.)

Regaining Control
As there are many different IoT devices and inherent vulnerabilities, patching can be overwhelming. That said, you can't protect what you can't see, so start with the basics: map out what you have and gain visibility into traffic, including the growing blind spot of encrypted traffic. This will allow you to introduce IoT security into your already existing security program. 

The next step is to ensure no default authentication is set for any of your devices and to start patching. Patching can't fix everything, but it can discourage any attackers probing your network. 

On the Linux side, there are enterprise-grade solutions available, some of which are more intrusive than others: they'll cover your assets at the cost of kernel intrusion. Other Linux-based solutions focus on visibility and monitoring "userland" behavior and processes. This allows you to keep more control, but also can result in easier bypasses for malware.

Conclusion
Although preparation is the key to addressing IoT and Linux cyberattacks, there is still much else that can be done. On the IoT side, device manufacturers need to develop a common set of security mechanisms and standards. Until that time, the best approach is to reduce the attack surface to a bare minimum: retire old devices, patch all devices that are a must, and use vendors that invest in security and enforce authentication wherever possible. On the Linux side, the situation is somewhat better, as software solutions and the main vendors continue to invest in securing the operating systems. However, there's no doubt that malware authors will persist in exploring and exploiting weaknesses in the OS and software whenever and wherever they find them.

While defenders need to seal every gap and plug every hole, an attacker just needs one way in. In some cases, that could come from your Linux and IoT. An IoT revolution is occurring, and the speed of change is bringing with it multiple security implications, some of which may be as yet unknown. The enterprise needs to be ready, and it needs to be vigilant.

Related Content:

Black Hat Europe returns to London Dec. 3-6, 2018, with hands-on technical Trainings, cutting-edge Briefings, Arsenal open-source tool demonstrations, top-tier security solutions, and service providers in the Business Hall. Click for information on the conference and to register.