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Least Privilege Separation Kernel Safety & Security for the Connected World Using a Separation Kernel to Protect against the Remote Exploitation of Unaltered Passenger Vehicles 16th June 2015 Mark Pitchford, Technical Manager, EMEA Today’s hot topic A few years ago, Lynx presentations at events such as this centred on why domain separation is key And then… http://www.wired.com/2015/07/hackers-remotely-kill-jeep-highway/ http://illmatics.com/Remote%20Car%20Hacking.pdf (c) Lynx Software Technologies. 2016. 2 Are Hypervisors a Panacea? Fast forward to today, and hypervisors are now held aloft as the solution to the challenges presented by these issues (c) Lynx Software Technologies. 2016. 3 Why a Hypervisor? Let’s start with a simpler example than a connected car Suppose we want a heart pacemaker to be able to report any irregularities back to a medical specialist. The primary role of the hypervisor here is to separate the “safe” and “unsafe” sides of the network Separation is key! (c) Lynx Software Technologies. 2016. 4 How safe is the separator? But what of the separation mechanism itself? Because this is a shared resource, it is imperative that it is as secure as possible. (c) Lynx Software Technologies. 2016. 5 Protecting against Remote Exploitation If a vehicle is to be optimally protected, the attack surface exposed to would-be aggressors needs to be minimised. – Separate high ASIL systems from those of lower criticality – Separate the TCP/IP stack away from the vulnerability of the gateway’s OS If they are to truly be separated rather than conjoined, we also need to minimize the resources – and hence the attack surface - shared between these entities (c) Lynx Software Technologies. 2016. 6 3 architectural approaches to separation in software Microkernel RTOS Type 1 Hypervisor Least Privilege Separation Kernel (c) Lynx Software Technologies. 2016. 7 Safety & Security for the Connected World Microkernel RTOS Microkernel RTOS Microkernel technology has its roots in an era predating hardware virtualization Back then, there were two privilege levels to consider – Supervisor and user privilege levels The Microkernel approach included some far sighted principles – Executed vulnerable code (such as the TCP/IP stack) in User Space, not Supervisor Space. (c) Lynx Software Technologies. 2016. 9 Virtualization in Enterprise • Then the Enterprise world brought us Hardware Virtualization… Source: IDC (c) Lynx Software Technologies. 2016. 10 Virtualization in Automotive …which has now also found a home in the Automotive sector on multi-core ARM Cortex-A based SoCs (e.g. the NXP S32V series) (c) Lynx Software Technologies. 2016. 11 Microkernel RTOS What’s an engineer to do? Ignore the additional VMM privilege level? – That would present a very vulnerable and unprotected attack surface Increase the privilege level of the microkernel and associated services? – That would see some software running at a higher privilege level than necessary Either way – not an ideal gestation (c) Lynx Software Technologies. 2016. 12 Safety & Security for the Connected World Type 1 Hypervisor Type 1 Hypervisor Consider KVM; an example from the Open Source Ecosystem which illustrates a wider issue – Kernel-based Virtual Machine (KVM) KVM is a virtualization infrastructure for the Linux kernel that turns it into a hypervisor* KVM makes use of hardware virtualization to support that hypervisor functionality *https://en.wikipedia.org/wiki/Kernel-based_virtual_machine (c) Lynx Software Technologies. 2016. 14 Type 1 Hypervisor This is a valid approach if the primary aim is to provide a hypervisor It is less attractive if the primary aim is separation KVM Linux exposes a minimum of 390 interfaces with hundreds of thousands parameter options implemented by 19.5 million lines of constantly changing code That code must be trusted to uphold VM isolation (c) Lynx Software Technologies. 2016. 15 Linux Kernel (c) Lynx Software Technologies. 2016. 16 Monolithic Hypervisor Architecture Guest OSs Services Apps API VM Monolithic Monitor Application Access Virtual I/O Policy Kernel CPU Scheduler Control Resource Mgmt Interrupt Handler I/O Stack Exception Handler Device Drivers - Storage, Network, Graphics… • “Separate the TCP/IP stack away from the vulnerability of the gateway’s OS” • Shared Resources = Large Attack Surface 17 (c) Lynx Software Technologies. 2016. Type 1 Hypervisor This underlying “helper OS” cannot and does not present – An optimal separation solution – A minimised attack surface For that, we have to return to the classroom and understand the principles of Least Privilege and Separation Kernels (c) Lynx Software Technologies. 2016. 18 Safety & Security for the Connected World The Least Privilege Separation Kernel Hypervisor Least Privilege Separation Kernel Hypervisor First mooted by John Rushby in 1981 Consists of a “combination of hardware and software that permits multiple functions to be realized on a common set of physical resources without unwanted mutual interference” Basic foundation of the Multiple Independent Levels of Security (MILS) initiative – a vision of modular building blocks for high-assurance secure systems (c) Lynx Software Technologies. 2016. 20 Least Privilege Separation Kernel Hypervisor 40-year-old concept (Saltzer and Schroeder) Per-subject and per-resource flow-control granularity – No subject needs to be given more access than that required to allow the desired flows Saltzer, J.H. and Schroeder, M.D. The Protection of Information in Operating Systems. Proceedings of the IEEE 63(9):1278-1308. 1975 (c) Lynx Software Technologies. 2016. 21 Least Privilege Separation Kernel Hypervisor SMP Safety Cert POSIX RTOS POSIX RTOS Linux Support for existing environments & applications Apps Apps Apps Apps Apps Apps Other Linux Android AUTOSAR Bare Bare Metal RTOS Metal Components LSA LSA FV/PV FV/PV FV/PV Component FV FV/PV FV Hardware (c) Lynx Software Technologies. 2016. 22 Monolithic vs Separation Kernel 23 (c) Lynx Software Technologies. 2016. Trusted Computing Base (TCB) Still a Separation kernel – NOT a cut down RTOS! (c) Lynx Software Technologies. 2016. 24 Separation Kernel based Distributed Vehicle Architecture Secure Update Gateway V2x Gateway Entertainment Gateway Firmware App App Server VM Server Server LSA. connect Tunneled Virtual Networks AUTOSAR LynxOS V2x Linux Encrypted Disk Partitions VM VM VM LSA.store VM V-NIC V-Disk V-NIC V-Disk V-NIC V-Disk Image Disk Network Manager VM Gateway VM VM Image VM Image (c) Lynx Software Technologies, 2016 25 Separation Kernel and Virtualization The combination of a separation kernel and hypervisor offers – Domain isolation, real-time determinism and high availability – Flexibility of application environments to bring legacy and modern OS environments – Bare-metal applications for safety and security The combination of a least-privilege separation kernel hypervisor and a modern multi-core processor represents the state-of- the-art to achieving separation in software (c) Lynx Software Technologies. 2016. 26 Safety & Security for the Connected World Thank You.
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