Alarm suppression is the deliberate hiding, muting, delaying, or disabling of alerts so operators do not see conditions that should trigger a warning. In operational technology, this can affect SCADA, HMI, or other monitoring layers that are supposed to tell staff when pressure, flow, temperature, or device state becomes unsafe.
It matters because alarms are part of the control system’s safety net. If an attacker suppresses them, operators may think a pump or process is behaving normally while the equipment is actually failing or being manipulated. In real attacks, suppression can be used to cover unauthorized changes, delay response, or create confusion while other actions continue. Defenders reduce this risk with separate alarm pathways, audit logging, alert integrity checks, strong access control, and procedures that compare live process data against independent indicators.