A denial-of-service attack restricts access to a computer or network in order to prevent intended users from using it. DoS attacks have become one of the go-to tools hackers employ in order to disturb the normal operation of computer-based services. One of the most effective approaches to completing such an attack is through a distributed approach.
Denial-of-service attacks can vary in their type and organization. Volumetric attacks depend on consuming the full bandwidth capacity of a network by flooding it with echo requests. Syn flooding attacks are similar, as they too consist of flooding the network with an overwhelming amount of requests; however, the attacker rapidly initiates a connection to a server without finalizing it. Fragmentation attacks seek to disrupt the inbuilt reassembling ability of the target network. Application layer attacks target undetected programming errors in an application or network by once again overwhelming the target with requests. Lastly, phlashing DoS attacks aim to permanently damage the target network by sending out false update requests and inserting malware throughout the network.
Distributed denial-of-service (DDoS) attacks are the most common type of malware attack. In order for a DDoS attack to work, hackers introduce malware to networks of connected devices and start bombarding them with a huge amount of requests, with the intention of overwhelming the network.
Unfortunately, cryptocurrency exchanges have become increasingly targeted by DDoS attacks because of their growing popularity. Since 2020, there have been numerous DDoS attack attempts on some of the major crypto exchanges. Unfortunately, this renders the exchange’s services unavailable for a prolonged period of time.
With the rise of applications of blockchain technology, a new type of DoS attack emerged — a blockchain denial-of-service (BDoS) attack. These attacks focus on blockchains operating under the proof-of-work (PoW) consensus mechanism like Bitcoin.
The way this new subtype of DoS works is by attacking the rewards mechanism for miners. The PoW consensus mechanism relies on miners to validate new blocks, and if miners do not receive their rewards, block validation is interrupted. It is important to note that it is significantly harder to perform a successful DoS attack on a decentralized network. While usually, DoS attacks rely on the centralized nature of traditional networks, this approach does not work with blockchain-based networks. In order to interrupt the mining process, attackers send fake proofs to the blockchain that they have a mining advantage. This discourages other miners from performing operations necessary for transaction validation, which essentially slows down the processing power of the blockchain significantly. Even so, BDoS attacks have been extremely rare and unsuccessful so far.