  Additive manufacturing (AM), or 3D printing, is an emerging manufacturing
technology that is expected to have far-reaching socioeconomic, environmental,
and geopolitical implications. As use of this technology increases, it will
become more common to produce functional parts, including components for
safety-critical systems. AM's dependence on computerization raises the concern
that the manufactured part's quality can be compromised by sabotage. This paper
demonstrates the validity of this concern, as we present the very first full
chain of attack involving AM, beginning with a cyber attack aimed at
compromising a benign AM component, continuing with malicious modification of a
manufactured object's blueprint, leading to the sabotage of the manufactured
functional part, and resulting in the physical destruction of a cyber-physical
system that employs this part. The contributions of this paper are as follows.
We propose a systematic approach to identify opportunities for an attack
involving AM that enables an adversary to achieve his/her goals. Then we
propose a methodology to assess the level of difficulty of an attack, thus
enabling differentiation between possible attack chains. Finally, to
demonstrate the experimental proof for the entire attack chain, we sabotage the
3D printed propeller of a quadcopter UAV, causing the quadcopter to literally
fall from the sky.
