​US puts medical device patching under the microscope

The US Food and Drug Administration (FDA) says medical device makers should take note of bug reports from external researchers and respond to security risks in a timely fashion.

The regulator published new guidelines on Wednesday detailing that manufacturers should “monitor, identify and address cybersecurity vulnerabilities and exploits” affecting medical devices that have been released to market.

The FDA has already published pre-market cyber security guidelines for network-connected medical devices and has now added non-enforceable recommendations for what manufactures should do post-market.

Network-enabled medical devices, such as some implantable defibrillators and pacemakers are, like other non-medical devices, a potential target for hackers. Medical devices differ in that they may serve a life-sustaining function and the FDA wants to ensure manufacturers have adequate processes in place to prevent and respond to weaknesses that could be exploited by attackers and lead to a malfunction of a device’s “essential clinical performance”.

The guidelines introduce tools and concepts familiar to most IT security professionals, such as the Common Vulnerability Scoring System (CVSS), which reflects on a scale of one to 10 the severity of any given flaw, based on whether it can be exploited remotely or locally, how complex an attack would need to be, and whether user interaction is required for exploitation.

It also divides medical device security into “controlled” and “uncontrolled” risks, with the latter referring to when there is an unacceptable risk that the device’s essential clinical performance could be compromised due to insufficient risk mitigations.

Reporting requirements are also addressed. The FDA generally will not need to approve software updates for devices and encourages “timely” cybersecurity risk management for marketed devices. However, it notes that manufacturers of devices that require pre-market approval should disclose the flaw in an annual report.

One example of a controlled risk is where a flaw leads to a component becoming infected by malware. So long as the “essential clinical performance” was not affected, it would not need to immediately report the weakness. However, if it was a high risk “Class III” device, the manufacturer would need to disclose details in an annual report.

Manufacturers are encouraged to report uncontrolled risks, however the FDA will not enforce reporting requirements so long as the manufacturer meets three conditions: no death is associated with the vulnerability; the manufacturer patches the issue within 30 days of learning of it and notifies users; and the manufacturer is participating in an information sharing an analysis organisation (ISAO).

Read more: Oracle to pour 155 fixes on top of Microsoft and Flash Patch Tuesday

One such ISAO is the US National Health Information Sharing & Analysis Center, which the FDA’s Center for Devices and Radiological Health has locked in an agreement with to encourage others to share information about medical device security and health IT infrastructure.

“All medical devices that use software and are connected to hospital and health care organizations’ networks have vulnerabilities—some we can proactively protect against, while others require vigilant monitoring and timely remediation,” said Dr Suzanne Schwartz, acting director of emergency preparedness/operations and medical countermeasures in the FDA’s Center for Devices and Radiological Health.

“The FDA is encouraging medical device manufacturers to take a proactive approach to cybersecurity management of their medical devices,” she added.

Kevin Fu, a US security researcher and one of the first experts to probe medical devices for security flaws, commended the FDA's post-market guidelines. He noted that the recommendations were difficult because they had more to do with people than technology.

But while remotely exploitable vulnerabilities are generally considered more severe than locally exploitable ones, Fu criticised the agency for limiting its analysis of infection vectors to networked devices rather than the "outcomes" of those infections.

"The final post-market guidance will need to more deliberately draw attention to outcomes of compromise and risks of vulnerabilities rather than the constantly evolving modality of delivery of exploits. After all, when we talk about surveilling for the spread of flu, we don't limit discussions to spread by cough versus spread by sneeze. Should the document list networked and connected devices as examples of infection vectors? Yes. Should it mention only networked and connected devices? No. Outcomes, not modalities."

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Tags medical devicesFDAcyber securityCSO AustraliaCommon Vulnerability Scoring System (CVSS)Food and Drug Administration (FDA)National Health Information Sharing & Analysis Center

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