Mass Exit Attacks on the Lightning Network

The security of the Lightning Network (LN) relies on the ability of the nodes to close a channel by settling their balances in case of malicious behaviors, which requires confirming a transaction on the Bitcoin blockchain within a pre-agreed time period. We study the susceptibility of the LN to mass exit attacks in case of high transaction congestion on layer-1, in the presence of a small coalition of adversarial nodes that forces a large set of honest users to interact with the blockchain, with the objective of locking or stealing users' funds. We show via simulations that, under historically-plausible congestion conditions, with mild statistical assumptions on channel balances, the proposed attacks can be performed by a small coalition.