What are distributed denial-of-service attacks and how do they work – SPE

Distributed Denial-of-Service (DDoS) cyber attacks are an important category of cyber threats that target digital and cyber-physical systems that rely on network availability, especially when systems rely on continuous communications for monitoring and control.

In these attacks, a target system, server, or network is overwhelmed by a massive amount of traffic generated by multiple compromised devices. Rather than intercepting communications like other types of attacks, DDoS attacks aim to deplete system resources, making services unavailable to legitimate users. As a result, operators may lose visibility and control over critical infrastructure.

DDoS attacks can also target PV systems and solar power plants connected to the grid, disrupting communications between controllers, inverters, SCADA systems and monitoring platforms. By flooding these systems with traffic, attackers can slow or completely block operational data exchange, potentially leading to system instability or shutdowns.

These attacks can also indirectly impose physical stress on inverters, transformers or panels by interrupting proper control signals or preventing timely fault detection. Furthermore, they can lead to lower energy production and recovery costs, while also posing safety risks for personnel working without real-time system visibility.

“DDoS attacks are especially risky for BESS operators. A BESS plant depends on real-time communications with the grid to participate in the stability markets. A DDoS attack will effectively block that communication with meaningless noise. This will impact the plant’s ability to generate revenue, sometimes without you even knowing about it,” Uri Sadot, Managing Director of SolarDefend and Chair of SolarPower Europe’s Digitalization Workstream, told me. pv magazine.

Operational modes

DDoS attacks can operate in volumetric mode, where large amounts of traffic flood network bandwidth, preventing legitimate communications from reaching their destination. Alternatively, they can function in application layer mode, focusing on specific services such as SCADA interfaces or monitoring application programming interfaces (APIs), becoming overwhelmed by repetitive requests that exhaust processing resources. In more advanced scenarios, protocol-based attacks exploit weaknesses in communications protocols to disrupt system functionality with relatively low traffic volumes.

For PV systems, a DDoS attack typically begins with the use of a botnet (a network of compromised devices) to generate traffic targeting critical components such as inverters, gateways or cloud-based monitoring platforms. These attacks often exploit publicly accessible interfaces or weakly protected communications endpoints. Once initiated, the flood of traffic saturates network connections or overloads system resources, preventing normal communication between devices.

Common techniques in PV environments include SYN floods, HTTP request floods, and amplification attacks that multiply traffic volume using misconfigured servers. In distributed solar farms, attackers can also target centralized monitoring platforms, effectively blinding operators at multiple locations simultaneously.

Once the attack is underway, operators may notice delayed data updates, loss of remote control capabilities, or complete communications failures. At this stage the attack is fully active, with the attacker continuing to apply pressure to prolong the disruption. Long-term attacks make recovery more complex as systems require manual intervention or a phased restart.

Defense

A potential defense against DDoS attacks in PV systems is to implement traffic filtering, rate limiting, and scalable network architectures that can absorb or divert large amounts of malicious traffic. If these measures are applied, traditional tools such as firewalls can become more effective by enforcing stricter traffic rules, blocking suspicious sources, and prioritizing legitimate communications.

Content Delivery Networks (CDNs) and DDoS mitigation services can also help by distributing traffic load and filtering malicious requests before they reach critical infrastructure. Additionally, redundancy in communication channels ensures that if one path becomes congested, alternative routes can maintain system connectivity.

Standard network segmentation can also help protect PV systems against DDoS attacks by isolating critical components such as inverters, SCADA systems and monitoring platforms into separate zones. This limits the impact of an attack on each individual segment. However, if key external interfaces remain exposed, attackers can still target entry points and disrupt essential services.

Intrusion Detection Systems (IDSs) can also help detect DDoS attacks in PV systems by identifying unusual traffic spikes, abnormal request patterns, or protocol abuse. They provide early warnings that allow operators to activate mitigation strategies. However, they cannot stop attacks on their own and must be integrated with automated response systems and traffic filtering mechanisms for effective protection.

Dismissal

In summary, DDoS attacks pose a serious risk to networked PV systems, mainly affecting their availability, operational continuity, financial performance and overall cybersecurity posture. While measures such as traffic filtering, rate limiting, redundancy, network segmentation, firewalls, and IDS can help reduce risk, none alone can fully protect the system.

Systems must be designed redundantly, continuously monitor traffic patterns and deploy automated mitigation strategies.

This approach not only helps maintain system availability during an attack, but also limits the attacker’s ability to sustain disruptions or extend their impact across interconnected systems.

“DDoS attacks are not a theory, they happen all the time. Looking at our industry, in a recent incident from 2024Japanese monitoring tools provider Contec announced that 800 of its products had been hijacked to form a DDoS botnet. said Sadot. “It’s a relatively simple attack, but it can be harmful. Fortunately, mitigation and prevention tools are readily available.”