Mitigating the Risk of Legacy Machines ICSSCADA Practice Questions (Page 6)

Questions 26–30

1. 26application · medium

   A wastewater treatment plant has a legacy PLC that communicates with a SCADA HMI over Ethernet. The PLC has known vulnerabilities and cannot be patched. The plant has implemented network segmentation, but the security team wants to add a host-based compensating control on the PLC. Which control is most feasible for a legacy PLC?

   • AUse a USB data diode to connect the PLC to the network.
   • BConfigure the PLC's built-in access control list (ACL) to restrict which IP addresses can communicate with it.
   • CInstall an endpoint detection and response (EDR) agent on the PLC.
   • DDeploy a host-based intrusion prevention system (HIPS) on the PLC.
   Reveal Solution Discussion Select an answer first
2. 27foundation · easy

   What is the main goal of network segmentation for legacy machines?

   • ATo isolate legacy machines from critical assets and external networks
   • BTo allow legacy machines to communicate with any device
   • CTo reduce the number of IP addresses needed
   • DTo increase the speed of the network
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4. 28application · medium

   A pharmaceutical plant has a legacy batch control system running Windows XP that has a known remote code execution vulnerability in its OPC server component. The vendor no longer provides patches, and a replacement is scheduled in 18 months. The system is on a flat network segment with other OT devices. Which compensating control BEST addresses the known vulnerability without altering the legacy software?

   • ADeploy a network-based intrusion prevention system (IPS) with a signature that blocks exploit traffic targeting the OPC server.
   • BUpgrade the OPC server component to the latest version available from the vendor.
   • CDisable the OPC server service on the legacy system and use a separate gateway for data exchange.
   • DApply a host-based firewall rule that blocks all inbound traffic to the legacy system except from the HMI workstation.
   Reveal Solution Discussion Select an answer first
5. 29foundation · easy

   Which technology is commonly used to implement network segmentation for legacy ICS machines?

   • AOverclocking the CPU
   • BVLANs (Virtual Local Area Networks)
   • CIncreasing RAM
   • DUsing a USB hub
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6. 30application · medium

   A chemical plant has a legacy HMI running Windows 2000 that is used to monitor a reactor temperature. The HMI is on the same flat network as the plant's business LAN, which has internet access. The HMI cannot be patched or upgraded. Which compensating control is MOST important to implement FIRST to reduce the risk of a remote attacker reaching the HMI from the internet?

   • AEnable the built-in Windows 2000 firewall on the HMI and configure it to allow only the reactor monitoring port.
   • BApply a virtual patch using a network IPS that blocks known exploit signatures targeting Windows 2000.
   • CInstall a host-based antivirus on the HMI with the latest signature definitions.
   • DSegment the HMI onto a separate OT network with a firewall that blocks all inbound traffic from the business LAN and internet.
   Reveal Solution Discussion Select an answer first