Authors:
Martin Salfer
and
Claudia Eckert
Affiliation:
Technische Universität München, Germany
Keyword(s):
Security Metrics, Embedded Systems, Cyber-Physical Systems, Exploit Engineering Cost Assessment.
Abstract:
Modern vehicles are controlled by an on-board network of ECUs (Electronic Control Units), which are specially
designed computers that contain tightly tailored and customized software. Especially the trends for ECU
connectivity and for semi-autonomous driver assistance functions may have an impact on passenger safety and
require thorough security assessments, yet the ECU divergence strains those assessments. We therefore propose
an easily automated, quantitative, probabilistic method and metric based on ECU development data and
software flash images for the attack surface and vulnerability assessment automation. Our method and metric
is designed for the integration into an (iterative) engineering process and the facilitation of code reviews and
other security assessments, such as penetration tests. The automotive attack surface comprises especially internal
communication interfaces, including diagnosis protocols, external and user-accessible interfaces, such
as USB sockets, as well as
low-level hardware interfaces. Some exemplary indicators for the vulnerability are
access restrictions, casing tamper-resistance, code size, previously found vulnerabilities; strictness of compilers,
frameworks and application binary interfaces; conducted security audits and deployed exploit mitigation
techniques. This paper’s main contributions are I) a method and a metric for collecting attack surface and
predicting the engineering effort for a code injection exploit from ECU development data, II) an application of
our metric and method on an example ECU and III) an integration into our graph-based security assessment.
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