Cross-chain bridges are crucial mechanisms for facilitating
interoperation between different blockchains, allowing the flow of
assets and information across various chains. Their pivotal role and the
vast value of assets they handle make them highly attractive to
attackers. Major security incidents involving cross-chain bridge
projects have been occurring frequently, resulting in losses of several
billion due to cyber attacks. The diversity of vulnerability
exploitation methods by hackers is vast, but not entirely untraceable.
There are scarce research outcomes studying cross-chain bridge cyber
incidents, and we have conducted a study based on the most recent
cross-chain bridge security incidents. We introduce the working
principles, components, and architecture of cross-chain bridges, explain
the categorization mechanisms of the trust layer in cross-chain bridges,
summarize four categories of hacker vulnerability exploitation
techniques from real cases, and propose preventative measures for
cross-chain bridge security.