The vulnerability is a Time-of-Check-Time-of-Use (CWE-367) issue which allows an attacker with access to the firmware update file to overwrite it after it has been verified (but before installation is completed), which consequently allows installing an arbitrary firmware update, bypassing the cryptographic signature check mechanism.
When the communication partner sends an invalid Modbus exception response to the FL COMSERVER UNI as a query, the Modbus communication stops, and the device will be unresponsive for some minutes before the functionality is fully restored (CWE-772).
An undocumented password protected FTP access to the root directory exists in certain devices of the AXL F BK and IL BK product families (CWE-798).
Phoenix Contact Classic Line industrial controllers are developed and designed for the use in closed industrial networks. The communication protocols and device access do not feature authentication measures. Remote attackers can use specially crafted IP packets to cause a denial of service on the PLC's network communication module (CWE-770).
Manipulated PC Worx or Config+ projects could lead to a remote code execution when unallocated memory is freed because of incompletely initialized data (CWE-824).
The attacker needs to get access to an original bus configuration file (*.bcp) to be able to manipulate data inside. After manipulation the attacker needs to exchange the original file by the manipulated one on the application programming workstation.