The invention relates to a system for protecting a computerized device from activities within the device bootstrap, which comprises: (a) a DC supply monitoring unit for monitoring power consumption of the DC supply of the device during bootstrap; and (b) a database for storing one or more valid bootstrap signatures, each of said valid bootstrap signatures describes a valid variation of power consumption pattern, respectively, from the DC supply of the device; wherein, during bootstrapping of the device, said DC supply monitoring unit continuously monitors the power consumption from said DC supply of the device, compares characteristics of the power consumption with said one or more valid bootstrap signatures in said database, and alerts upon detection of a mismatch.