Blipcare Wifi blood pressure monitor BP700 10.1 devices allow memory corruption that…

Summary

Blipcare Wifi blood pressure monitor BP700 10.1 devices allow memory corruption that results in Denial of Service. When connected to the "Blip" open wireless connection provided by the device, if a large string is sent as a part of the HTTP request in any part of the HTTP headers, the device could become completely unresponsive. Presumably this happens as the memory footprint provided to this device is very small. According to the specs from Rezolt, the Wi-Fi module only has 256k of memory. As a result, an incorrect string copy operation using either memcpy, strcpy, or any of their other variants could result in filling up the memory space allocated to the function executing and this would result in memory corruption. To test the theory, one can modify the demo application provided by the Cypress WICED SDK and introduce an incorrect "memcpy" operation and use the compiled application on the evaluation board provided by Cypress semiconductors with exactly the same Wi-Fi SOC. The results were identical where the device would completely stop responding to any of the ping or web requests.