Read MCU embedded firmware is a complicate technology and data romance can be one of the main technologies. The general process of data remanence is through keeping the security key inside the processor in the state of static RAM, the component will power off whenever the MCU read set up and component being manipulated, and the content inside the RAM will get lost, which can protect the security key from being stolen by MCU read. As we all know once the temperature around the MCU is below minus 20 degree, the content inside the RAM will be frozen. Lots of the MCUs will defined the terms as a read temperature whenever the surround temperature below this point. We have done some related experiments about the connection and relations among the security key and data keeping capability inside modern MCU with the temperature outside. Our experiment has proved that the traditional thoughts about the MCU read is no more effective. Even in the high temperature, the data remanence is still a problem even in the high temperature. The data remanence of MCU read has effect not only on the SRAM, but also the DRAM, UV EPROM, EEPROM and flash.

As a result of that, the remaining information can still be obtained from the already erased MCU after read which will bring a lot of security issue with the facility.