What Is a DDoS Attack in Crypto? A Guide to Defense in 2025

What Is a DDoS Attack — A Brief Overview

A DDoS (Distributed Denial of Service) attack floods a service with traffic from multiple sources, overloading it with millions of fake requests in seconds. The target—whether a website, exchange, or wallet—crashes and becomes inaccessible to legitimate users.

How a DDoS Attack Works

Think back to shopping for sneakers online: you go to the website, select your shoes in the correct size, and submit the order. But if someone triggers a DDoS attack at that moment, hundreds of thousands of bots hit the site simultaneously, “pretending” to browse products, add them to the cart, and even start checkout.

The site overloads, begins to lag, and soon stops responding. In the end, you, a normal buyer, cannot load the page – the site is frozen. Cryptocurrency services face the same fate: during a DDoS attack, they are swamped by bogus requests, fail to handle the increased load, and become inaccessible to genuine users.

Types of DDoS Attacks

Among the most typical forms of DDoS attacks on cryptocurrency services are volumetric attacks, where the infrastructure of a project (such as an exchange, RPC nodes, or decentralized wallets) is swamped by an overwhelming volume of fake traffic.

Protocol-targeted attacks are more elaborate. They exploit weaknesses in protocols like TCP, UDP, or ICMP, forcing node servers or API interfaces to spend capacity on incomplete or stalled connections, thereby denying real users access. 

The most dangerous are app-level attacks that copy ordinary user behavior. Bots log onto the exchange, verify their identity, check balances, place orders, or operate the DeFi protocol interface. It seems legit, yet runs at industrial scale – blocking real users from accessing the service.

Botnet-Based Attacks

To perform a DDoS attack, malicious actors often harness a botnet – a centrally managed collection of infected devices. These can include personal computers, smartphones, servers, or IoT devices (such as cameras), with owners typically oblivious to their involvement.

Through the botnet, the attacker can enlist thousands or millions of devices worldwide to send large volumes of requests to the target – whether it’s an exchange, wallet, or blockchain node – overwhelming network links and processing resources. This triggers service disruptions and server failures, preventing real users from accessing the service. Because the attack traffic is distributed and mimics normal activity, it is extremely hard to filter out.

Perhaps the best-known example is the Mirai botnet, which searched the internet for insecure IoT devices, compromised them, and leveraged them for wide-reaching attacks. In 2016, it incapacitated major DNS providers, resulting in outages on Twitter, Reddit, Netflix, and others. Within the crypto sphere, comparable botnets are used to assault exchanges and decentralized services, stoking user alarm and damaging platform credibility.

Why and How DDoS Attacks Occur in the Crypto Ecosystem

DDoS is rarely a random fault; it’s usually a meticulously planned strategic act. The attackers’ motives vary.

• Extortion (Money): There are documented cases where hackers first disrupt a service and then demand payment from the owners to halt the assault.

• Competitive Sabotage: Crypto exchanges or projects can be hit by competitors during critical moments – such as a new token launch, a major upgrade rollout, or turbulent market times – to scare off users and gain an edge.

• Ideological Reasons: Decentralized platforms may face attacks from those hostile to Web3, and centralized exchanges can be targeted by advocates of full decentralization. Sometimes the sole intent is to sow disorder – to shatter trust in the project, depress the token’s value, trigger panic sell-offs, and upset market equilibrium.

Points of Vulnerability in Crypto Infrastructure

The cryptocurrency ecosystem consists of many components, each potentially open to DDoS attacks. Let’s examine the chief ones.

Centralized Exchanges (CEX)

The biggest crypto exchanges have frequently been in the crosshairs of DDoS attacks. For example, in April 2020, Binance’s Chinese domains were targeted in an attack that led to delays and service failures. Binance CEO Changpeng Zhao hinted that competitors might have instigated the attack to weaken the exchange’s reputation.

How DApps Can Be Disrupted

DApps use multiple infrastructure layers – frontend interfaces, RPC servers, oracles, and so on. Attacks against these layers may impair the application. Take September 2021: Solana endured a 17-hour outage after bots overloaded the network with upwards of 400,000 transactions per second, draining validators’ resources and halting block production.

Wallets, API Endpoints, and Nodes

These elements are essential to cryptocurrency network functionality. If wallets or API endpoints are overwhelmed, users may be unable to execute transactions or access their assets. Nodes that handle transaction processing and uphold consensus are likewise susceptible to DDoS attacks, which can undermine network stability. For instance, attacks that flood nodes can introduce processing delays and, in extreme cases, lead to hard forks of the blockchain.

Layer-1 vs Layer-2

DDoS attacks might be directed at the blockchain’s base level (Layer–1) or at second-layer (Layer-2) implementations. Layer-1 is the fundamental chain that upholds security and consensus. Layer-2 includes solutions layered above the base blockchain – such as payment channels and sidechains – aimed at enhancing scalability and speeding up transactions. Targeting Layer-1 can trigger significant outages throughout the network, while targeting Layer-2 may undermine the performance and stability of particular applications or services.

Notable Crypto DDoS Incidents

Crypto platforms have experienced several major DDoS attacks with notable operational impact.

Kraken (November 2015)

In late 2015, Kraken faced a wave of DDoS attacks starting October 31 and stretching into the first days of November. These attacks prevented users from logging in or trading by overloading the platform, causing intermittent outages and connection issues.

On November 4, the assault intensified, temporarily taking the site offline. This surge coincided with Bitcoin’s climb to $500, amplifying user dissatisfaction. The attackers sent a ransom demand in BTC; Kraken refused to pay, stating that yielding would only spur further attacks. The exchange then strengthened defenses and alerted users that, since the attack persisted, service interruptions could continue.

Bitfinex (December 2017)

In December 2017, crypto exchange Bitfinex was targeted by a string of robust DDoS attacks. The company reported on December 4 that its servers were under significant assault, a situation that lasted until December 7. Less than a week afterward, Bitfinex endured a further heavy DDoS incident, causing short-term service interruptions and necessitating a suspension of new user onboarding to stabilize operations. These attacks took place during a sharp Bitcoin upswing, likely enticing attackers hoping to benefit from the turmoil.

Bitcoin.org (July 2021)

During July 2021, the Bitcoin.org information site was hit by an “absolutely massive” DDoS attack. The perpetrators demanded 0.5 BTC (about $17,000 at the time) in ransom to end the attack. The operator, known under the pseudonym Cøbra, voiced outrage, highlighting that the site serves only as an educational platform and holds no user data or funds.

DDoS Mitigation Measures

A holistic approach is needed to guard against DDoS attacks.

• Traffic filtering: Detect and block suspicious requests to prevent resource exhaustion.
• CDNs and cloud deployment: Spread incoming traffic via Content Delivery Networks and cloud services to mitigate attack severity.
• Monitoring and early detection: Maintain continuous traffic oversight and use intrusion-detection systems for rapid identification of attacks.
• Incident response planning: Establish a clear, actionable plan for DDoS incidents to reduce downtime and limit losses.
• Capacity enhancement: Invest in infrastructure with greater bandwidth and resilience to accommodate high traffic volumes.

Often, DDoS attacks are deployed to mask other, more elaborate schemes – whether it’s a breach or to shift focus from a leak. Hence, defending is only half the battle; analyzing these incidents is equally vital. With blockchain’s inherent transparency, proper on-chain analytics can help uncover where an attack came from and who orchestrated it.