REVIEW 3 major objections 8 minor 38 references
A hardware firewall that watches a 3D printer's motors, temperatures, fans, and endstops can catch firmware attacks that alter the print or damage the machine.
Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →
T0 review · grok-4.5
2026-07-14 11:21 UTC pith:BX2TJLM7
load-bearing objection Solid, non-invasive hardware prototype that actually catches the firmware attacks it claims to catch; the trusted-G-code assumption is the real limit, not a hidden flaw. the 3 major comments →
Firewall3D: A Hardware Firewall for Defending 3D Printers Against Firmware Attacks
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Firewall3D can detect a wide range of firmware attacks that compromise print integrity, damage components, or leak intellectual property by monitoring physical-layer signals in real time and verifying that the printer's actual behavior matches the intended G-code; on mismatch it can alarm and stop the print.
What carries the argument
Firewall3D, a bump-in-the-wire hardware monitor that samples stepper-motor coil currents (decoded via atan2 into position and speed), temperature sensors, fan PWM-to-DC voltages, and endstop lines, then compares them against expected G-code values.
Load-bearing premise
The intended G-code must be known securely to Firewall3D or its host PC, and an attacker must not be able to reprogram Firewall3D itself or tamper with its communication channel.
What would settle it
Run a firmware attack that alters motion length, speed, temperature, fan duty, or endstop behavior while Firewall3D is installed; if the board fails to flag the mismatch or produces false alarms on legitimate prints across a range of feed rates and temperatures, the detection claim fails.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper presents Firewall3D, a custom “bump-in-the-wire” hardware monitor placed between a 3D printer’s motherboard and its actuators/sensors. Using an STM32-based PCB with Hall-effect current sensors, PWM-to-DC converters, buffered temperature/endstop paths, and an atan2-based decoder of dual-coil stepper currents (Algorithm 1, §4.9), it reconstructs nozzle motion, speed, temperatures, fan duty, and endstop events and compares them to an externally supplied intended G-code stream. Controlled experiments report ±0.1 mm position resolution (Table 1, Appendix Table 2), speed error under 1% on fixed-length moves (Fig. 10), and successful detection of hand-crafted motion-length, motion-speed, thermal-setpoint, fan-speed, and endstop-spoofing attacks (§6, Figs. 11–15). On anomaly the system can alarm and halt printing. Limitations (§7) explicitly assume a trusted G-code reference and an uncompromised Firewall3D/PC channel.
Significance. If the result holds under the stated threat model, this is a useful systems contribution: the first purpose-built, non-invasive hardware firewall for commodity FFF printers that closes a gap left by software-only and invasive (soldered) monitors. Strengths that should be credited include a fully realized PCB and circuits (§4.2–4.8), a concrete, reproducible position decoder (Algorithm 1), quantitative accuracy tables rather than qualitative claims, and coverage of three attack classes (motion, thermal/fan, endstop) drawn from prior firmware-attack literature. The work is timely given the growth of AM and documented firmware threats (Marlin, FLAW3D, bio-printer attacks). The main value is engineering demonstration and a clear physical-layer monitoring architecture, not a new cryptographic or formal security theorem.
major comments (3)
- §3 Threat Model and §4.6 / §7: The central detection claim (“physical behavior matches the intended G-code”) is load-bearing on a trusted, uncompromised G-code reference delivered to Firewall3D (or its host PC) while the printer may receive a maliciously altered command. All attack simulations in §4.6 and §6 are constructed exactly this way (original command to Firewall3D, modified command to the printer). The paper acknowledges this in §7 but does not design or evaluate a concrete secure G-code path (e.g., authenticated streaming, measured SD-card path through the host, or cryptographic binding). Without that, the system detects motherboard/firmware deviation only when the reference is already known to be correct; an attacker who can also influence the reference channel (or the host that supplies it) falls outside the demonstrated guarantee. This assumption should be elevated into the t
- §5–§6 Evaluation: Detection is shown only on short, hand-crafted G-code snippets and controlled trajectories (square paths, step temperature ramps, single-axis homing). There are no false-positive or false-negative rates on long multi-layer production prints, no characterization of threshold sensitivity under vibration, thermal drift, or filament-load variation, and no multi-printer or multi-firmware validation. Table 1 and Figs. 10–12 establish reconstruction accuracy under ideal conditions; they do not establish operational detection reliability. For a security claim that Firewall3D “can effectively detect a wide range of firmware attacks” and safely halt printing, the manuscript needs at least (i) FP statistics on several full real G-code jobs and (ii) a clear statement of detection latency and halt mechanism under continuous streaming. Without these, the “wide range / effective” clai
- §1 Related work and comparison to SCREAM [7]: The paper correctly notes that [7] is invasive (soldering between MCU and driver) while Firewall3D measures after the driver and is more portable. However, there is no side-by-side quantitative comparison of detection coverage, latency, position/speed error, or attack classes. Given that the authors themselves state [7] “achieves performance similar to our system,” a short comparison table (signals monitored, invasiveness, accuracy, attacks demonstrated) is needed so readers can judge the incremental contribution. As written, novelty relative to the closest prior hardware monitor remains under-specified.
minor comments (8)
- Abstract and §1: Market figure “exceeding $30 billion” and Apple Watch Ultra 3 example are fine for motivation but should cite the exact MarketsandMarkets / Apple sources already listed in the bibliography for reproducibility.
- §4.9 / Algorithm 1: The conversion “every ten π/4 increments = 0.1 mm” is printer-specific. State the steps/mm or microstepping configuration used, and note how recalibration would work on a different machine (currently only implied).
- §4.2 Fan circuit: PWM frequency is given as 7.8 Hz for “our 3D printer.” Confirm whether this is typical Marlin fan PWM or a board-specific setting; many boards use higher frequencies, which would require retuning the RC filter.
- Fig. 9 caption says temperature increments of 25°C while the body text (§5.2) says 50°C steps from 50°C to 200°C. Align caption and text.
- Fig. 10 caption says “motion path of length 200mm” while the surrounding text discusses 20 mm motions and Appendix Fig. 18 uses 25 mm. Clarify the length used for each speed-error plot.
- §6.4 thermal model: α ≈ 2.3 °C/s and β = 10% are reasonable but presented without uncertainty bounds or dependence on ambient temperature / PID gains. A short sensitivity note would strengthen the defense claim.
- Typos / consistency: “Firewall3d” vs “Firewall3D”; “Avgerage” in Table 1; “scenraio” in Fig. 15 caption; “commends” in Fig. 14 caption; duplicated reference [2]/[3] (same HOST 2025 bio-printer paper).
- §2.1: “logical high signal of 0 V” for released endstop is confusing; rephrase as active-low / open-collector behavior if that is the case.
Circularity Check
No significant circularity; physical-signal matching to known G-code is independent experimental validation, not a self-referential derivation.
full rationale
Firewall3D's core claim is an engineering result: a bump-in-the-wire monitor that samples stepper currents (via TMCS1107 + atan2 phase decoding + printer-specific scale of ten π/4 increments = 0.1 mm), PWM-to-DC fan/bed signals, NTC temperatures, and end-stop states, then flags mismatches against an externally supplied G-code reference. The conversion factor, heating-rate coefficient α ≈ 2.32 °C/s, and speed-timing windows are ordinary printer-specific calibrations obtained from controlled G-code runs (Tables 1–2, Figs. 8–10, 13); they are not fitted to attack outcomes and then re-labeled as predictions of those same outcomes. Attack scenarios (§6) are simulated by deliberately sending the original command to Firewall3D and a mutated command to the printer; detection is therefore a direct comparison of independent physical observables, not a tautology. Self-citations ([5], [6]) address prior side-channel or streaming work by the same authors and are not load-bearing for the Firewall3D detection logic or uniqueness claims. The trusted-monitor assumption (§7) is an explicit threat-model boundary, not circular reasoning. The paper is therefore self-contained against its own experimental benchmarks; score 1 only for the presence of non-load-bearing self-citations.
Axiom & Free-Parameter Ledger
free parameters (3)
- position conversion factor (ten π/4 increments = 0.1 mm) =
0.1 mm per 10 increments
- heating-rate coefficient α ≈ 2.3 °C/s =
≈2.32 °C/s
- safety factor γ and tolerance β = 10 % =
β = 0.1 T_set
axioms (4)
- domain assumption Physical signals after the motor drivers and on the sensor lines faithfully reflect the commands actually executed by the (possibly compromised) firmware.
- ad hoc to paper The intended G-code is known to Firewall3D / the host PC and the communication channel between them is secure.
- ad hoc to paper Attacker cannot modify Firewall3D firmware or its wiring after installation.
- domain assumption Stepper motors produce approximately circular current trajectories whose phase can be recovered by atan2.
invented entities (1)
-
Firewall3D hardware platform
no independent evidence
read the original abstract
As the 3D printing market continues to grow rapidly, with an estimated value exceeding $30 billion, cybersecurity risks and attacks targeting additive manufacturing systems are also increasing. These attacks aim to sabotage printed components, steal intellectual property, or even physically damage the 3D printer itself. One major cybersecurity threat in this domain is firmware level attacks, which can be introduced through supply chain compromises, malicious firmware updates, or insider threats that deploy modified firmware to manipulate printer behavior. To defend against such threats, we propose a dedicated hardware based security solution,Firewall3D, that acts as a hardware firewall for 3D printers. Firewall3D continuously monitors physical layer signals, including stepper motor currents, end stop switches, nozzle and bed temperatures and cooling fans, to verify that the printer's physical behavior matches the intended G-code execution. Our experimental results demonstrate that Firewall3D can effectively detect a wide range of firmware attacks that could compromise print integrity, damage printer components, or leak intellectual property. Upon detecting abnormal behavior, the system can immediately trigger an alarm and halt the printing process, thereby preventing further damage and risks.
Figures
Reference graph
Works this paper leans on
-
[1]
Global 3D Printing Market Size, Share, Latest Trends & Growth Analysis, 2024-2029 — marketsandmarkets.com.https://www.marketsandmarkets.com/ Market-Reports/3d-printing-market-1276.html, [Accessed 14-07-2025]
2024
-
[2]
In: 2025 IEEEInternationalSymposiumonHardwareOrientedSecurityandTrust(HOST)
Ahsan, M., Najarro-Blancas, B., Ebode, J.T., Lewinski, N., Ahmed, I.: 3d bio- printer firmware attacks: Categorization, implementation, and impacts. In: 2025 IEEEInternationalSymposiumonHardwareOrientedSecurityandTrust(HOST). pp. 99–110. IEEE (2025)
2025
-
[3]
In: 2025 IEEEInternationalSymposiumonHardwareOrientedSecurityandTrust(HOST)
Ahsan, M., Najarro-Blancas, B., Ebode, J.T., Lewinski, N., Ahmed, I.: 3d bio- printer firmware attacks: Categorization, implementation, and impacts. In: 2025 IEEEInternationalSymposiumonHardwareOrientedSecurityandTrust(HOST). pp. 99–110 (2025).https://doi.org/10.1109/HOST64725.2025.11050047
-
[4]
Journal of Manufacturing Processes145, 211–235 (2025)
Ali, H., Cano, A., Ahmed, I.: Machine learning-based early detection of malicious g-code manipulations in 3d printing. Journal of Manufacturing Processes145, 211–235 (2025)
2025
-
[5]
arXiv preprint arXiv:2602.02198 (2026)
Asgar, S.A.G., Reddy, N.: Quietprint: Protecting 3d printers against acoustic side- channel attacks. arXiv preprint arXiv:2602.02198 (2026)
Pith/arXiv arXiv 2026
-
[6]
arXiv preprint arXiv:2507.06421 (2025)
Asgar, S.A.G., Reddy, N., Bukkapatnam, S.T.: Never trust the manufacturer, never trust the client: A novel method for streaming stl files for secure additive manu- facturing. arXiv preprint arXiv:2507.06421 (2025)
Pith/arXiv arXiv 2025
-
[7]
In: Proceedings of the ACM Asia Conference on Computer and Communications Security
Basu Roy, P., Blocklove, J., Bhargava, M., Pearce, H., Krishnamurthy, P., Sinanoglu, O., Gupta, N., Khorrami, F., Karri, R.: Scream: Secure channels for real-time evaluation of additive manufacturing. In: Proceedings of the ACM Asia Conference on Computer and Communications Security. pp. 234–249 (2026)
2026
-
[8]
Smart and Sustainable Manufacturing Systems1(1), 142–152 (2017)
Baumann, F.W., Ludwig, T., Darwin Abele, N., Hoffmann, S., Roller, D.: Model- Data Streaming for Additive Manufacturing Securing Intellectual Property. Smart and Sustainable Manufacturing Systems1(1), 142–152 (2017)
2017
-
[9]
In: 26th USENIX Security Symposium (USENIX Security 17)
Bayens, C., Le, T., Garcia, L., Beyah, R., Javanmard, M., Zonouz, S.: See no evil, hear no evil, feel no evil, print no evil? malicious fill patterns detection in additive manufacturing. In: 26th USENIX Security Symposium (USENIX Security 17). pp. 1181–1198 (2017)
2017
-
[10]
IEEE Embedded Systems Letters14(3), 111– 114 (2021)
Beckwith, C., Naicker, H.S., Mehta, S., Udupa, V.R., Nim, N.T., Gadre, V., Pearce, H., Mac, G., Gupta, N.: Needle in a haystack: Detecting subtle malicious edits to additive manufacturing g-code files. IEEE Embedded Systems Letters14(3), 111– 114 (2021)
2021
-
[11]
arXiv preprint arXiv:2506.21897 (2025)
Chattopadhyay, T., Ceschin, F., Garza, M.E., Zyunkin, D., Chhotaray, A., Stebner, A.P., Zonouz, S., Beyah, R.: One video to steal them all: 3d-printing ip theft through optical side-channels. arXiv preprint arXiv:2506.21897 (2025)
Pith/arXiv arXiv 2025
-
[12]
Progress in materials sci- ence92, 112–224 (2018)
DebRoy, T., Wei, H.L., Zuback, J.S., Mukherjee, T., Elmer, J.W., Milewski, J.O., Beese, A.M., de Wilson-Heid, A., De, A., Zhang, W.: Additive manufacturing of metallic components–process, structure and properties. Progress in materials sci- ence92, 112–224 (2018)
2018
-
[13]
Benha Journal of Applied Sciences10(7), 9–28 (2025)
Elgez, A.G.M., Elgedawy, N.K., Nada, O.A.E.: Intellectual property protection for 3d printing products using blockchain technology in the field of industrial design. Benha Journal of Applied Sciences10(7), 9–28 (2025)
2025
-
[14]
Gao, Y., Li, B., Wang, W., Xu, W., Zhou, C., Jin, Z.: Watching and safeguarding your3dprinter:Onlineprocessmonitoringagainstcyber-physicalattacks.Proceed- ings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 2(3), 1–27 (2018) Firewall3D 23
2018
-
[15]
In: Proceedings of the 24th International Symposium on Research in Attacks, Intrusions and Defenses
Gatlin, J., Belikovetsky, S., Elovici, Y., Skjellum, A., Lubell, J., Witherell, P., Yam- polskiy, M.: Encryption is futile: Reconstructing 3d-printed models using the power side-channel. In: Proceedings of the 24th International Symposium on Research in Attacks, Intrusions and Defenses. pp. 135–147 (2021)
2021
-
[16]
Gibson, I., Rosen, D.W., Stucker, B., Khorasani, M., Rosen, D., Stucker, B., Kho- rasani, M.: Additive manufacturing technologies, vol. 17. Springer (2021)
2021
-
[17]
In: International Con- ference on Security and Privacy in Cyber-Physical Systems and Smart Vehicles
Jamarani, A., Tu, Y., Hei, X.: Practitioner paper: Decoding intellectual property: Acoustic and magnetic side-channel attack on a 3d printer. In: International Con- ference on Security and Privacy in Cyber-Physical Systems and Smart Vehicles. pp. 54–74. Springer (2025)
2025
-
[18]
In: Security and Privacy in Cyber-Physical Systems and Smart Vehicles: Second EAI International Conference, SmartSP 2024, New Orleans, LA, USA, November 7–8, 2024, Proceedings
Jamaranil, A., Tu, Y., Heil, X.: Practitioner paper: Decoding intellectual prop- erty: Acoustic and magnetic. In: Security and Privacy in Cyber-Physical Systems and Smart Vehicles: Second EAI International Conference, SmartSP 2024, New Orleans, LA, USA, November 7–8, 2024, Proceedings. vol. 622, p. 54. Springer Nature (2025)
2024
-
[19]
Com- puters in Industry173, 104395 (2025)
Kumar, M., Epiphaniou, G., Maple, C.: Securing additive manufacturing with blockchain-based cryptographic anchoring and dual-lock integrity auditing. Com- puters in Industry173, 104395 (2025)
2025
-
[20]
Journal of Manufacturing Processes145, 274–285 (2025)
Mishra, A.K., Goh, S.Y., Ganapathysubramanian, B., Krishnamurthy, A.: Real time 3d reconstruction for enhanced cybersecurity of additive manufacturing pro- cesses. Journal of Manufacturing Processes145, 274–285 (2025)
2025
-
[21]
In: 2016 Resilience Week (RWS)
Moore, S., Armstrong, P., McDonald, T., Yampolskiy, M.: Vulnerability analysis of desktop 3d printer software. In: 2016 Resilience Week (RWS). pp. 46–51. IEEE (2016)
2016
-
[22]
Moore, S.B., Glisson, W.B., Yampolskiy, M.: Implications of malicious 3d printer firmware (2017)
2017
-
[23]
Engineering Research Express 6(2), 025404 (2024)
Moulika, G., Palanisamy, P.: Optimizing extreme manufacturing framework: a se- cure and efficient 3d printing integration framework. Engineering Research Express 6(2), 025404 (2024)
2024
-
[24]
Pearce, H., Yanamandra, K., Gupta, N., Karri, R.: Flaw3d: A trojan-based cyber attack on the physical outcomes of additive manufacturing. IEEE/ASME Trans- actions on Mechatronics27(6), 5361–5370 (2022).https://doi.org/10.1109/ TMECH.2022.3179713
arXiv 2022
-
[25]
In: International Conference on Availability, Reliability and Security
Puch, N., Dopfer, S., Birkel, L.: Securing the additive manufacturing process chain. In: International Conference on Availability, Reliability and Security. pp. 340–358. Springer (2025)
2025
-
[26]
In: 18th USENIX WOOT Conference on Offensive Technologies (WOOT 24)
Rais, M.H., Ahsan, M., Ahmed, I.:{SOK}: 3d printer firmware attacks on fused fil- ament fabrication. In: 18th USENIX WOOT Conference on Offensive Technologies (WOOT 24). pp. 263–282 (2024)
2024
-
[27]
In: International Conference on Critical Infrastructure Protection
Rais, M.H., Ahsan, M., Sharma, V., Barua, R., Prins, R., Ahmed, I.: Low- magnitude infill structure manipulation attacks on fused filament fabrication 3d printers. In: International Conference on Critical Infrastructure Protection. pp. 205–232. Springer (2022)
2022
-
[28]
Additive Manufac- turing46, 102200 (2021)
Rais, M.H., Li, Y., Ahmed, I.: Dynamic-thermal and localized filament-kinetic attacks on fused filament fabrication based 3d printing process. Additive Manufac- turing46, 102200 (2021)
2021
-
[29]
https://www.apple.com/newsroom/2025/11/mapping-the-future- with-3d-printed-titanium-apple-watch-cases (2025), [Accessed: 14-07-2025] 24 SA
Redding, S., Rothberg, N.: Mapping the future with 3d-printed titanium ap- ple watch cases. https://www.apple.com/newsroom/2025/11/mapping-the-future- with-3d-printed-titanium-apple-watch-cases (2025), [Accessed: 14-07-2025] 24 SA. Ghazi Asgar and N.Reddy
2025
-
[30]
In: 34th USENIX Security Symposium (USENIX Security 25)
Rossel, J., Mladenov, V., Wördenweber, N., Somorovsky, J.: Security implications of malicious{G-Codes}in 3d printing. In: 34th USENIX Security Symposium (USENIX Security 25). pp. 1867–1885 (2025)
2025
-
[31]
International Journal of Computer Integrated Manufacturing pp
Shomenov, K., Ali, M.H., Jyeniskhan, N., Al-Ashaab, A., Shehab, E.: Cost-effective sensor-based digital twin for fused deposition modeling 3d printers. International Journal of Computer Integrated Manufacturing pp. 1–20 (2025)
2025
-
[32]
In: Proceedings of the 2016 ACM SIGSAC Conference on Computer and Commu- nications Security
Song, C., Lin, F., Ba, Z., Ren, K., Zhou, C., Xu, W.: My smartphone knows what you print: Exploring smartphone-based side-channel attacks against 3d printers. In: Proceedings of the 2016 ACM SIGSAC Conference on Computer and Commu- nications Security. pp. 895–907 (2016)
2016
-
[33]
Jour- nal of Materials Chemistry A13(16), 11804–11816 (2025)
Sonigara, K.K., Vaghasiya, J.V., Mayorga-Martinez, C.C., Pumera, M.: Point-of- use upcycling of 3d printing waste for developing 3d-printed zn–i 2 batteries. Jour- nal of Materials Chemistry A13(16), 11804–11816 (2025)
2025
-
[34]
Applied Sciences11(11), 5305 (2021)
Stańczak, A., Kubiak, I., Przybysz, A., Witenberg, A.: The possibility to recreate the shapes of objects on the basis of printer vibration in the additive printing process. Applied Sciences11(11), 5305 (2021)
2021
-
[35]
International Journal of Science and Research Archive14(2), 638–645 (2025)
Thakare, S.B., Poddar, S.: Secure mechanical design and manufacturing: Pre- venting ip theft via cybersecurity. International Journal of Science and Research Archive14(2), 638–645 (2025)
2025
-
[36]
Bukkapatnam, S.T.: Cybersecurity assur- ance in the emerging manufacturing-as-a-service (MaaS) paradigm: A lesson from the video streaming industry
Tiwari, A., Narasimha Reddy, A.L., S. Bukkapatnam, S.T.: Cybersecurity assur- ance in the emerging manufacturing-as-a-service (MaaS) paradigm: A lesson from the video streaming industry. Smart and Sustainable Manufacturing Systems4(3), 324–329 (2020)
2020
-
[37]
Materials today21(1), 22–37 (2018)
Tofail, S.A.M., Koumoulos, E.P., Bandyopadhyay, A., Bose, S., O’Donoghue, L., Charitidis, C.: Additive manufacturing: scientific and technological challenges, market uptake and opportunities. Materials today21(1), 22–37 (2018)
2018
-
[38]
Yuan, J., Zhou, Y., Chen, G., Xiao, K., Lu, J.: Materials vs digits: A review of embedded anti-counterfeiting fingerprints in three-dimensional printing. Materials Science and Engineering: R: Reports160, 100836 (2024) Firewall3D 25 Appendix Detecting start/stop motion Listing 1.1 demonstrates the hardware pin toggling mechanism that signals the completion...
2024
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.