Which of the following vulnerabilities is MOST likely to adversely impact unpatched programmable-logic controllers and OT systems accessible over the Internet?

Weak encryption is the most likely vulnerability to adversely impact unpatched programmable-logic controllers (PLCs) and operational technology (OT) systems accessible over the Internet because these devices often control critical infrastructure and industrial processes. If they are using weak encryption protocols, it could allow attackers to easily intercept and manipulate data transmitted between the PLCs and other network components.

Many PLCs and OT systems may not have been designed with modern security standards in mind, making them particularly susceptible to exploitation of weak encryption. This can lead to unauthorized access, where malicious actors can gain control over these systems or disrupt their operation, posing significant risks to safety and security.

In contrast, other vulnerabilities such as cross-site scripting typically target web applications rather than OT systems, data exfiltration might be a risk but is more relevant in contexts where sensitive information needs to be stolen rather than manipulating system operations, and server-side request forgery is specific to web services and doesn’t specifically pertain to programmable logic controllers or OT systems directly.