Often referred to as A Dark Forest, Ethereum is home to predatory trading bots that prey on user transactions. Frontrunning is made simpler on Ethereum as builders & validators are incentivised to process the highest fee transactions first. One suggested mitigation strategy is to process transactions in a pseudo-random order, preventing frontrunners from predictably affecting transaction execution order. XRP Ledger, one of the oldest blockchains to use pseudorandom ordering, is launching an Automated Market Maker. This study investigates whether frontrunning techniques commonly observed in Ethereum Automated Market Makers are feasible on the XRP Ledger Automated Market Maker. In summary, our findings demonstrate that with minor adjustments, the conventional Sandwich Attack is feasible. Additionally, we unveil a distinctive attack facilitated by the integration with the Close Limit Order Book.

Blockchains are disrupting traditional finance by reducing the number of intermediaries and providing transparency. Blockchains, however, come with their own set of prominent issues. One such challenge is frontrunning. Attackers try to influence the transaction order so that their transaction executes before their victims' transaction. While frontrunning is a well-studied topic on Ethereum, it is unknown whether other blockchains are also susceptible to such attacks. One proposed defence strategy against frontrunning attacks is to randomize the transaction execution order. XRP Ledger is the highest-value blockchain to use such a strategy. Furthermore, it runs a Decentralized Exchange, which provides ample frontrunning opportunities. Therefore, in the context of XRP Ledger, we examine whether randomized transaction order provides sufficient protection against frontrunning. Our results show that the mechanism embedded in the XRP Ledger protocol is insufficient to prevent these attacks. We showcase two strategies to perform frontrunning attacks. The first, “naive” strategy, uses randomly generated accounts, whereas the second uses carefully selected accounts to improve the attack's success. Based on our analysis of the XRP Ledgers' historical data, we estimate that attackers could generate up to approx. 1.4M USD profit over two months, provided they succeeded to frontrun every opportunity.

Federated Byzantine Agreement protocols applied in the XRP Ledger and Stellar use voting to reach a consensus. Participants of these protocols select whom to trust in the network and effectively communicate with the trustees to reach an agreement on transactions. Most trustees, for example 80% in the XRP Ledger, must agree on the same transactions for them to appear in the blockchain. However, disruptions to the communication between the trustees can prevent the trustees from reaching an agreement. Thus, halting the blockchain. In this paper, we propose a novel robustness metric to measure the Federated Byzantine Agreement protocol tolerance to node failures. We show that the XRP Ledger Consensus Protocol is vulnerable to targeted attacks. An attacker has to disconnect only 9% of the highest-degree nodes to halt the blockchain. We propose a mitigation strategy which maintains critical XRP Ledger network topology properties whilst increasing the robustness up to 45%.

The XRP Ledger relies on a trusted set of validator nodes to advance the ledger history. Nodes use flood-based broad-casting to disseminate messages. Flooding offers strong message delivery guarantees at the cost of high network utilisation caused by duplicate messages. In this paper, we present pemcast, an application layer algorithm for efficient one-to-many message routing. The algorithm leverages limited topology awareness and application layer multi-casting to deliver messages in the network. The evaluation shows that compared to flooding and gossiping algorithms, pemcast can maintain similar reliability whilst generating significantly less redundant traffic.