Data and configuration settings within an ICS may be compromised by all human access from other zones that is not controlled (or are inadequately controlled) by internal on-site personnel. In particular, personnel from external maintenance providers, integrators, and manufacturers may have the necessary specialised knowledge of the equipment being maintained, but insufficient knowledge of secure remote OT maintenance.

If the processes and contents of OT remote maintenance sessions cannot be adequately controlled by the operator, it may not be possible to detect and trace potentially high-risk configuration errors and unintentional or intentional misconduct by maintenance personnel quickly enough. This can lead to failures or manipulations of real-time data streams or the unnoticed spread of malware throughout the OT at hand. Ultimately, this can result in damage to life and limb of the operating personnel on site, high financial losses due to production downtime, and even the destruction of entire plants. The disclosure of trade secrets is also possible. In addition, the integrity of manufactured products can be compromised (e.g. by manipulating formulas to produce defective goods that may be difficult to detect). A failure to detect defective products can damage an organisation's reputation.

One example could involve decentralised OT remote maintenance components within facilities that are implemented as a complete system by the manufacturer (package units). These remote maintenance access points are often designed to allow the manufacturer to access the system at any time. If this happens without coordination with the operator's personnel, it can lead to hazardous situations in the current production process, for example.