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 Codes: 0023, 002e, and 0037 Fault Type: Recoverable Description: The STI, EII, and HSC function files contain bits signifying whether or not a fault has occurred. Additionally there is a bit signaling the module to auto start. When these bits are set for any of the three modules and the device is moved into a run state, a fault is triggered.