# A Review of Industry 4.0 Manufacturing Process Security Risks
## 4 Solutions
### Side-Channel Analysis  
With the possibility that a cyber-physical attack can avoid detection within the systems network domain, the focus on industrial manufacturing security solutions should be extended to the side-channel domain. This involves the monitoring of the actual manufacturing process from an external perspective where the dynamic aspects of the manufacturing equipment are monitored and verified against an authentic and confirmed baseline. In this approach, it is possible to detect if a manufacturing process has been compromised if any step performed in the manufacturing process does not pass a verification test against the baseline. Production can then immediately be halted to investigate the deviation from the correct manufacturing procedure. This would prevent the complete manufacturing of products with compromised structural integrity, before such products enter the market if they somehow pass quality control during post-production inspections.  
The approach of side-channel analysis will require the use of various types of sensors that are finely calibrated in order to provide the most accurate measurements possible to be used for verification. A three-level approach for detecting attacks by means of side-channel analysis is presented in [55]. The first aspect in this approach is to model an attacker in the context of the industrial systems network in order to determine the possible attack vectors that an attacker could exploit. With the possible attack vectors identified, it immediately becomes clear where special attention should be paid to the security and monitoring of the production/manufacturing process. The second aspect involves the modeling of the industrial processes with specific focus on the relationship between control signals and analog emissions (such as machine noise patterns, noise levels and even ambient temperature) by the industrial equipment. Attacks on the manufacturing systems network can then be detected if there is any deviation from the simulated model. Lastly, the relationship between analog emissions and control system parameters is analyzed to provide a measurement metric against which side-channel measurements can be measured.  
Expanding on the work presented in [55], further research and development have been performed to formulate these side-channel analysis methods in [56]. According to the authors of [56], attacks that are only detected by means of side-channel analysis could be considered zero-day attacks, since there is a high probability that the attacker exploited a vulnerability unknown to security institutions. Therefore, side-channel analysis will play an important role in the detection and future prevention of cyber-physical attacks, since zero-day vulnerabilities could potentially be detected sooner during the attack lifecycle. However, some fundamental challenges are associated with side-channel analysis techniques. For example, experiments in [56] indicated that accelerometers used in spatial verification are prone to outputting very noisy data, resulting in low digital reconstruction resolution, making it difficult to inspect the real-time (and post-production) digital reconstruction of a manufacturedproduct against a modeled baseline. There are thus some fundamental challenges that still need to be addressed in developing effective side-channel analysis solutions.