Dynamic-thermal and localized filament-kinetic attacks on fused filament fabrication based 3D printing process

3D printing materializes physical objects through sequentially depositing thin layers. The layer-by-layer stacking involves controlling 3D printing parameters (e.g., fan speed, nozzle temperature, printing bed temperature, and filament extrusion rate) to ensure conformity to a CAD (Computer-aided Design) model. Attackers target the parameters during a printing process to sabotage the printing object. This paper presents four new sabotage attacks on the fused filament fabrication (FFF)-based 3D printing process: (1) cavity through filament-kinetics, (2) density variation through filament state, (3) density variation through filament speed, and (4) dynamicthermal manipulation. These attacks produce an insignificant attack footprint on a finished printed object by targeting localized regions or using small changes in temperature profile, making them hard to detect. Specifically, the first three attacks manipulate filament-kinetics to change the print density or create a cavity in a small localized region, while the fourth attack makes slight changes to the nozzle temperature to manipulate thermal stress in a printing object without creating any visual deformation. Mechanical (tensile and three-point bending) tests carried out on the objects under attack demonstrate that these attacks with insignificant attack footprints can still change the physical properties (e.g., stress and strain) of the printed objects.