A method and system for securely monitoring an operating system of a mobile wireless communication device for unauthorized modifications. A secure application is provided on universal integrated circuit card of the mobile wireless communication device. The secure application is configured to control the wireless connectivity of the mobile wireless communication device, and communicate with a wireless communications network. A monitoring application is provided in a trusted sub-processor of the processor of the mobile wireless communication device. A secure communication link is established between the secure application and the monitoring application. A heartbeat token is generated by the trusted sub-processor, based on a modification status for the operating system and at least one system variable. The secure application receives the heartbeat token, and determines that an unauthorized software modification exists based on the heartbeat token. The secure application activates at least one countermeasure when an unauthorized software modification exists.