Cybersecurity threats and their impact on barrier effectiveness in safety instrumented systems: A systematic review

Increasing connectivity between operational and information technology environments introduces adversarial disturbance pathways not represented in conventional safety instrumented system (SIS) safety and reliability assumptions. Existing studies address industrial control system vulnerabilities or extend safety analysis to cyber scenarios, but a consolidated, lifecycle-oriented understanding of how cyber attacks influence SIS safety integrity remains limited. This systematic literature review of 92 studies examines cyberattack degradation of SIS safety integrity and protection-layer effectiveness. Using a structured taxonomy, the analysis shows that cyber-induced disturbances affect SIS through interacting technical, organizational, and cognitive pathways, driven by unauthorized access, control-logic manipulation, and information-layer deception. Cybersecurity controls prevent or contain compromise, whereas the SIS responds to hazardous physical deviations; cyber compromise can invalidate assumptions about its independence, availability, or correct action without constituting a random failure mode. The evidence base relies heavily on analytical studies, with limited experimental or incident-based validation. Gaps remain in lifecycle integration, standards alignment, and socio-technical factors. These findings support empirically grounded, lifecycle-oriented methods that keep adversarial security risk distinct from probabilistic SIL verification while testing whether cyber compromise invalidates the assumptions underlying barrier effectiveness and safety integrity.