We study an auction with $m$ identical items in a context where $n$ agents can arbitrarily commit to strategies. In general, such commitments non-trivially change the equilibria by inducing a metagame of choosing which strategies to commit to. In this model, we demonstrate a strategy that an attacker may commit to that ensures they receive one such item for free, while forcing the remaining agents to enter into a lottery for the remaining items (albeit for free). The attack is thus detrimental to the auctioneer who loses most of their revenue. For various types of auctions that are not too congested, we show that the strategy works as long as the agents have valuations that are somewhat concentrated. In this case, all agents will voluntarily cooperate with the attacker to enter into the lottery, because doing so gives them a chance of receiving a free item that would have otherwise cost an amount commensurate with their valuation. The attack is robust to a large constant fraction of the agents being either oblivious to the attack or having exceptionally high valuations (thus reluctant to enter into the lottery). For these agents, the attacker may coerce them into cooperating by promising them a free item rather than entering in to the lottery. We show that the conditions for the attack to work hold with high probability when (1) the auction is not too congested, and (2) the valuations are sampled i.i.d. from either a uniform distribution or a Pareto distribution. The attack works for first-price auctions, second-price auctions and the transaction fee mechanism EIP-1559 used by the Ethereum blockchain.

翻译：我们研究了一个包含$m$个相同物品的拍卖场景，其中$n$个智能体可任意提交策略。一般而言，这种通过诱导选择策略的元博弈会非平凡地改变均衡。在该模型中，我们展示了一种攻击者可能提交的策略：该策略确保攻击者免费获得一个物品，同时迫使其余智能体参与剩余物品的抽签（尽管抽签本身免费）。因此，该攻击对失去大部分收益的拍卖方极为不利。对于多种未过度拥挤的拍卖类型，我们证明只要智能体的估值相对集中，该策略即可生效。此时，所有智能体会自愿配合攻击者参与抽签，因为此举使其有机会免费获得原本需支付与估值相当费用的物品。该攻击对相当大比例（常数级）的智能体具有鲁棒性——这些智能体或未察觉攻击、或持有异常高估值（因而拒绝参与抽签）。对于此类智能体，攻击者可通过承诺免费提供物品（而非让其参与抽签）来胁迫其配合。我们证明，当以下条件成立时，攻击生效条件以高概率成立：（1）拍卖未过度拥挤；（2）估值独立同分布于均匀分布或帕累托分布。该攻击适用于一级价格拍卖、二级价格拍卖以及以太坊区块链采用的交易费机制EIP-1559。