An exploitable access control vulnerability exists in the data, program, and function file permissions functionality of Allen Bradley Micrologix 1400 Series B FRN 21.2 and before. A specially crafted packet can cause a read or write operation resulting in disclosure of sensitive information, modification of settings, or modification of ladder logic. An attacker can send unauthenticated packets to trigger this vulnerability. Required Keyswitch State: REMOTE or PROG or RUN Description: The value 0xffffffff is considered NaN for the Float data type. When a float is set to this value and used in the PLC, a fault is triggered.  NOTE: This is not possible through RSLogix.