How to prevent DDoS attacks in blockchain?


Across today’s digital space, blockchain networks are pivotal in securing and decentralizing a great number of apps and entire financial systems. Despite the techonology’s resilience, however, it is not immune to threats, DDoS attacks being one of them. These malicious acts can disrupt blockchain networks significantly by overloading them with fraudulent transactions and compromising smart contracts.

What are DDoS attacks?

A distributed denial-of-service (DDoS) attack is aimed to take down a website, computer or online service by flooding it with requests. Thus, it depletes its capacity to respond to valid queries.

A DDoS attack involves hackers infecting thousands of internet-enabled devices, collectively referred to as a botnet, and prompting them to deliver a deluge of requests to the target system simultaneously. These compromised machines, individually termed bots or zombies, could be cellphones, desktops, servers or even Internet of Things (IoT) devices. Attackers usually establish direct control over bots by infecting them with malware without the knowledge of the victims. prompting them to deliver a multitude of requests to the target system simultaneously. These compromised gadgets, aka bots or zombies, could be cellphones, PCs, servers or even Internet of Things (IoT) devices. Crooks typically take over these bots by inserting a malware into them behind the victim’s back.

The incoming traffic from botnet overloads the target system’s ability to process queries because the attack consumes too much bandwidth, computing power or memory. In its Q1 2024 DDoS threat report, Cloudflare noted an alarming 50% rise in DDoS attacks as compared to last year figures.

Is DDoS attack possible to do on a blockchain?

Technically, a blockchain network could become the target of a DDoS attack, but this is more complicated than attacking centralized systems such as websites or servers. Blockchain networks are foolproof to such attacks thanks to their decentralized nature.

A blockchain operates as a decentralized distributed ledger, functioning across an array of nodes, which are responsible for validating and processing transactions and creating blocks. As opposed to traditional systems, there is no central point of control within a blockchain network. Decentralization makes a blockchain network harder to attack as attackers need to deal with a multitude of nodes.

One way to disrupt the network is by flooding the blockchain with spam transactions, which overwhelms the network and slows down transaction throughput, hindering the timely validation of legitimate transactions. This queues up transactions from genuine users in the mempool, a mechanism in blockchain nodes that stores unconfirmed transactions.

A notorious instance of a DDoS attack was one on the Solana blockchain network, which led to a 17-hour downtime back in September 2021. During Grape Protocol’s initial decentralized exchange offering (IDO) on the Solana-based DEX Raydium, bots bombarded the network with 400,000 transaction loads per second, causing network congestion.

Moreover, DDoS attacks may target decentralized applications (DApps) built on top of the blockchain, rather than the blockchain network itself. Crypto exchanges, which are paramount in ensuring liquidity in a blockchain-based ecosystem, frequently fall victim to DDoS attacks, resulting in temporary service outages.

How can DDoS attacks affect blockchain networks?

As previously stated, DDoS attacks can affect blockchain networks via transaction flooding and compromising smart contracts. The objective here is to clog the network with fraudulent transactions, slowing it down and, in the worst case scenario, bringing it to a halt.

Transaction flooding

Fraudsters can intentionally overload a blockchain network with a voluminous number of transactions, disrupting its normal operations. The attackers would then give a blast of transaction queries, using automated scripts or specialized software. These transactions resemble legitimate ones but are designed to overload the network.

The attackers broadcast these transactions to the nodes. To achieve consensus, the network distributes the transactions across multiple nodes, which work to process these transactions. However, the volume of incoming transactions overwhelms their processing capacity. The network becomes congested and even genuine transactions get stuck in the backlog. 

Smart contracts

Hackers can identify vulnerable smart contracts in a blockchain network and flood them with transaction requests. These transactions contain fraudulent instructions or excessive computations to exhaust the functionality of the contract and the underlying network. The execution of code in the smart contract becomes increasingly burdensome, leading to inordinate delays in transaction validation.

As smart contracts are a key part of blockchains, the impact of such an attack may propagate across the network, affecting other smart contracts and transactions, disrupting critical operations and rendering services inaccessible to legitimate users. 

Software crashes

Core application software in blockchains has built-in limits regarding the memory allocated and the number of transactions it can process in a block and store in the mempool. When there is a uptick in transactions, the software might behave unexpectedly or simply crash.

Moreover, immutability means they simply cannot be altered once they are recorded in blocks. The network gets overloaded with useless transactions, which might be much beyond the software’s ability to handle.

Node failure

Nodes, acting as validators or miners, run the core blockchain software on equipment robust enough to handle the rigorous demand. When malicious actors stream in loads of junk data in a DDoS attack, a node might run out of memory or processing power and crash. This might increase pressure on the other nodes in the network.

Blockchain networks are essentially an amalgamation of nodes where each receiving node keeps track of the state of the blockchain and broadcasts information regarding transactions to other nodes. Flooding of fraudulent transactions affects the node architecture deleteriously, slowing down the whole network or even pulling it down.

How to prevent DDoS attacks on blockchain?

To protect blockchain networks from DDoS attacks, security measures are required at the node and network levels. Regular audits take care of vulnerabilities, while redundant infrastructure and stress testing keep the network functioning even during an attack.

Node-level security measures

Nodes should have adequate storage, processing power and network bandwidth to be resilient against DDoS attacks. Strong authentication methods and access controls help to protect network nodes. A CAPTCHA is quite useful in ensuring only legitimate users are able to send transaction requests and prevents bots from infiltrating the network. Load balancing helps in dividing traffic and lessening the effect of node-level attacks.

Network level protection

Putting in place adequate defense mechanisms at the network level is important to safeguard a blockchain network. To identify and reduce the impact of DDoS attacks, firewalls and intrusion detection/prevention systems (IDS/IPS) serve well. Content delivery networks (CDNs) are also helpful in dispersing and absorbing attack traffic.

Audits

To find and fix any vulnerabilities, a thorough audit of various aspects of the blockchain is vital. This should include analyzing smart contracts, auditing the integrity of the blockchain’s data structure and validating consensus algorithms. Fault tolerance in consensus mechanisms should be strong enough to resist attacks. Updating the code regularly is important to keep attackers at bay and improve security.

Stress testing

Performing stress testing of blockchain protocols from time to time helps evaluate their resilience to DDoS attacks. This will facilitate the detection of potential vulnerabilities in time, enabling patching of the network infrastructure and upgrading of defense mechanisms.

Redundancy and backup

Blockchain protocols and DApps need to have redundant network infrastructure and backup servers to ensure that the system keeps functioning even when under attack. Nodes located across multiple geographical locations can hold out against a DDoS attack that is limited to a specific region.

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