LOW-MAGNITUDE INFILL STRUCTURE MANIPULATION ATTACKS ON FUSED FILAMENT FABRICATION 3D PRINTERS

As 3D printing applications in industry verticals increase, researchers have been developing new attacks on additive manufacturing processes and appropriate defense techniques. A major attack category on additive manufacturing processes is printed object sabotage. If an attack causes obvious deformations, the part will be rejected before it is used. However, the inherent layer-by-layer printing process enables malicious actors to induce hidden defects in the internal layers of finished parts. The stealthiness of an attack increases its chances of evading detection and the printed part being used in an operational environment where it can cause harm. Several detection schemes have been proposed for identifying attacks on external and internal features of printed objects, but all these schemes have detection thresholds that are well above printer accuracy. Reducing the attack magnitude to the order of printer accuracy can evade detection.This chapter describes two infill structure manipulation attacks that are easy to launch at the cyber-physical boundary and evade conventional cyber security tools by employing subtle printed part variations below the detection horizon. Specifically, the magnitudes of the variations fall within the printer resolution and trueness values, rendering it challenging for detection schemes to differentiate printed part modifications from benign printing errors. Destructive testing demonstrates that the infill structure manipulation attacks consistently reduce the strength of printed parts. This chapter also highlights the need to incorporate the physical characteristics of printed parts in attack detection.