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 Associated Fault Code: 0012 Fault Type: Non-User Description: A fault state can be triggered by overwriting the ladder logic data file (type 0x22 number 0x02) with null values.