On Thursday, June 23, 2022, a hacker successfully carried out a malicious attack to steal $100 million from Harmony's Horizon blockchain bridge and withdraw tokens stored on the bridge (HZ) through 11 transactions, but Harmony's Bitcoin Bridge remained unaffected by the attack.
Blockchain bridge designs such as Harmony's Horizon primarily enable users to move assets between different blockchains, including tokens, stablecoins, and NFT.
Harmony halted the Horizon Bridge immediately after the attack to prevent further transactions. It then contacted the FBI and multiple cybersecurity and exchange partners to investigate, track and assist in retrieving stolen assets. Only after those contacts were established did Harmony announce the hack via Twitter and its blog post.
The identities of the hackers appear to have been established, as the investigation team has tried to communicate with their addresses using embedded information from the transactions and is awaiting a response.
In a blog post, the company said:
"This event is a humbling and unfortunate reminder of how important our work is to the future of this space and how much work remains to be done. . We are working around the clock to ensure the investigation and recovery of stolen funds is completed in the most effective manner."
This year alone, the blockchain world has seen three hacks targeting blockchain Bridges, with more than $1 billion in stolen funds.