What is a key vulnerability of the modbus protocol in ICS systems?

Focusing on the modbus protocol as it is utilized in Industrial Control Systems (ICS), a primary vulnerability stems from its lack of built-in security measures. The correct answer emphasizes that the protocol does not prevent command injection attacks, which can allow an adversary to send unauthorized commands to devices that utilize modbus.

Command injection occurs when an attacker is able to exploit vulnerabilities in the input validation of applications to execute arbitrary commands. In the context of modbus, this lack of protection can lead to significant operational risks, as malicious commands could manipulate the functions of equipment, causing failure or unsafe conditions within critical infrastructure.

While some might consider attributes like encrypted data or connectivity features in assessing protocol security, modbus primarily operates in a clear text format without robust encryption, making it inherently susceptible to interception and unauthorized control. This oversight in command authorization highlights the need for enhanced security measures when implementing modbus in ICS environments.