Why Microsoft Windows is a bad idea for medical devices

I’m getting some push back on LinkedIn on my articles on banning Microsoft Windows from medical devices that are installed in hospitals – read more about why Windows is a bad idea for medical devices here and here.

Scott Caldwell tells us that the FDA doesn’t rule “out” or “in” any particular technology, including Windows Embedded.

Having said that, Microsoft has very clear language in their EULA regarding the use of Windows Embedded products:

“The Products are not fault-tolerant and are not designed, manufactured or intended for any use requiring fail-safe performance in which the failure of a Product could lead to death, serious personal injury, severe physical or environmental damage (“High Risk Activities”).”

Medical device vendors  that  use Windows operating systems for less critical devices, or for the user interface are actually increasing the threat surface for a hospital, since any Windows host can be a carrier of malware that can take down the entire hospital network, regardless of it’s primary mission function, be it user-friend UI at a nursing station or intensive care monitor at the bedside.

Medical device vendors that use Microsoft IT systems management “best-practices” often  take the approach of “bolting-on” third party solutions for anti-virus and software distribution instead of developing robust, secure software, “from the ground up” with a secure design, threat analysis, software security assessment and secure software implementation.

Installing third-party security solutions that need to be updated in the field, may be inapplicable to an embedded medical device as the MDA (Medical Device Amendments of 1976) clearly states:

These devices may enter the market only if the FDA reviews their design, labeling, and manufacturing specifications and determines that those specifications provide a reasonable assurance of safety and effectiveness. Manufacturers may not make changes to such devices that would affect safety or effectiveness unless they first seek and obtain permission from the FDA.

It’s common knowledge that medical device technicians use USB flash drives and notebook computers to update medical devices in the hospital. Given that USB devices and Windows computers are notoriously vulnerable to viruses and malware, there is a reasonable threat that a field update may infect the Windows-based medical device. If the medical device is isolated from the rest of hospital network, then the damage is  localized, but if the medical device is networked to an entire segment, then all other Windows based computers on that segment may be infected as well – propagating to the rest of the hospital in a cascade attack.

It’s better to get the software security right than to try and bolt in security after the implementation.Imagine that you had to buy the brakes for a new car and install them yourself after you got that bright new Lexus.

It is not unusual for medical device vendors to fall victim to the same Microsoft marketing messages used with enterprise IT customers – “lower development costs, and faster time to market” when in fact, Windows is so complex and vulnerable that the smallest issue may take a vendor months to solve. For example – try and get Windows XP to load the wireless driver without the shell.   Things that may take months to research and resolve in Windows are often easily solved in Linux with some expertise and a few days work. That’s why you have professional medical device  software security specialists like Software Associates.

With Windows, you get an application up and running quickly, but it is never as reliable and secure as you need.

With Linux, you need expertise to get up and running, and once it works, it will be as reliable and secure as you want.

Yves Rutschle says that outlawing Microsoft Windows from medical devices in hospitatls  sounds too vendor-dependant to be healthy (sic) (Seems to me that this would make the medical device industry LESS vendor-dependent, not more vendor-dependent, considering the number of embedded Linux options out there.)

Yves suggests that instead, the FDA should create a “proper medical device certification cycle. If you lack of inspiration, ask the FAA how they do it, and maybe make the manufacturers financially responsible for any software failure impact, including death of a patient“. (The FDA does not certify medical devices, they grant pre-market approval).

I like a free market approach but consider this:

(Held)The MDA’s pre-emption clause bars common-law claims challenging the safety or effectiveness of a medical device marketed in a form that received premarket approval from the FDA. Pp. 8–17.

Maybe the FDA should learn from the FAA but in the meantime, it seems to me if the FDA pre-market validation process had an item requiring a suitable operating system EULA, that would pretty much solve the problem.

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