Forensic Analysis of Compromised Medical Devices

Introduction to Forensic Analysis of Compromised Medical Devices

Forensic analysis of a medical device means working backward from a failure to its cause. A continuous glucose monitor (CGM) is a small sensor under the skin that measures glucose in the surrounding fluid every few minutes and sends the result to a display device [4]. When one fails, the cause could sit in the wireless link, in the sensor's physical parts, or in the software that turns its signal into a number. Investigators split the work to match: digital forensics for the wireless link and software, material forensics for the hardware, and data forensics for the signal itself.

Digital Forensics in CGMs

The digital side of an investigation centers on the link between the sensor's transmitter and the receiver or phone that shows readings [4]. The risk is documented for wireless medical devices. In March 2020 the FDA warned that SweynTooth, a family of vulnerabilities in Bluetooth Low Energy (BLE), a short-range radio standard, could introduce risks for certain medical devices, and it has posted cybersecurity alerts for Medtronic MiniMed insulin pumps in 2019 and 2022 [1]. Outside medicine, a 2025 study ran four man-in-the-middle attacks, in which an attacker sits between two devices and relays or alters their messages, against eight BLE fitness trackers. The trackers proved partly vulnerable, and newer models were more likely to be attackable [2].

For glucose data, three attack types matter most: eavesdropping (listening in on readings), signal spoofing (sending fake readings that look real), and replay attacks (resending an old, valid message so false glucose data enters the system). A replayed or spoofed packet tends to give itself away through its sequence number or timestamp, which won't fit the order of the real stream. Analysts look for those anomalies to tell an attack apart from ordinary sensor noise. Here's what surprised us: for every case on its cybersecurity safety-communication list, the FDA says it is not aware of any patient injuries or deaths tied to a cybersecurity incident [1]. More on that list is in our article on cybersecurity in connected CGM ecosystems.

Material Forensics for Device Failure Analysis

When a sensor breaks, the evidence is the sensor itself. Retained wire is a real, published problem: a 2025 case report described a 2-year-old whose X-ray showed metal fragments consistent with retained CGM sensor wires in his thigh, and surgeons removed two shallow pieces but left two deeper ones because removing them risked injury or bleeding [3]. The authors noted that a raised nodule or lasting pain at an old insertion site should raise suspicion of retained wire, which is something to bring to your care team [3].

To find out why a wire broke, engineers use Scanning Electron Microscopy (SEM), which images a fracture surface at very high magnification. The surface can separate a break from one excessive pull during insertion or removal (tensile overload) from a crack that grew slowly under repeated bending (fatigue failure), which raises questions about design or manufacturing. We could not find a published study applying this method to explanted CGM sensors, so read it as the general engineering approach rather than an established CGM protocol.

Data Forensics for Identifying Hardware Instability

A CGM never shows you what it measures directly. The sensor measures an electrical signal proportional to glucose in the interstitial fluid, and software converts that raw signal into a glucose value through calibration [4]. Many systems also run real-time digital filters to strip out measurement noise before a number appears [4]. That smoothing helps, but it can make a struggling sensor look steady. Comparing the raw signal with the filtered output is how an analyst checks whether software was covering for unstable hardware. Our article on signal processing algorithms in CGM explains the filtering in more detail.

The body is the other suspect. Within days of insertion, proteins and inflammatory cells wrap the sensor in a layer researchers call biofouling, part of the wider foreign body response, and these tissue reactions have been linked to the short working life of implanted glucose sensors [5]. Telling slow biological drift like this apart from deliberate interference matters more now that CGM readings feed closed-loop insulin delivery systems, the "artificial pancreas" [4]. Whether to use or change such a system is a decision to make with your care team.

Conclusion

Each method answers a question the others can't: a wireless log can't show a cracked wire, and an SEM image can't show a spoofed packet. The bigger gap is public evidence. The FDA's list of cybersecurity safety communications covers insulin pumps, patient monitors and cardiac devices, but as of October 2026 it names no CGM [1], and we could not find a published forensic case study of an attack on one.