White Paper

WHITE PAPER 7 Tenets of Layered Security in Embedded Design mrcy.com 2 mrcy.com 2 Securing your system is no longer as simple as preventing entry. We have to assume that the attacker is already in. It's not a fair fight . . . When tasked with securing an embedded system, you (the defender) must be prepared to protect against every possible vulnerability. Overlook a single opening and the attacker may find it, take control, steal your secrets, and create an exploit for others to use anytime, anywhere. Worse yet, that same attacker may use an initial compromised device to pivot from one exploited subsystem to another, causing further damage to your network, mission, and reputation. This white paper covers the most important security design principles that, if adhered to, give you a fighting chance against any attacker who seeks to gain unauthorized access, reverse engineer, steal sensitive information, or otherwise tamper with your embedded system. TENET BRIEF EXPL ANATION PRODUCTS AND SERVICES Threat Modeling Define potential threats and requirements to the system. This should be the precursor to finding security solutions for the system. Individualized Security Assessment Data at Rest Protection Prevent data, including application from being modified and / or accessed offline. DM-verity, Forti/FS/AuthFS Attack Surface Reduction Minimize dependencies and trusted computer base. Establish limited, well-defined interfaces across the system. Kernel Hardening and Allowlisting Syscall Filters Secure and Immutable Configuration Establish a secure configuration for the system and the ensure this configuration cannot be modified. Secure Boot and Forti/FS/AuthFS Kernel Hardening, DM-verity Least Privilege Limit privileges for all components to only access what is necessary to perform the intended function(s). RelianceOne for Linux Policy MAC enforcement, Syscall filtering Audit and Event Logging Capture and analyze system logs for security relevant events to identify possible attacks or vulnerabilities in the system. Audit Logging Secure Updates Facilitate a mechanism to perform software / configuration updates in a secure fashion. Secure Boot The beauty of these 7 tenets is that they can be layered together into a cohesive set of countermeasures that achieve a multiplicative effect, making device exploitation significantly difficult and costly for the attacker. . "When tasked with securing an embedded system, you (the defender) must be prepared to protect against every possible vulnerability."

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