Alexander Gurevich Block, who is accused of exploiting a security vulnerability in a cryptocurrency platform to steal millions of dollars worth of tokens, was extradited from Israel to the United States early Thursday.
Block, who was born Alexander Gurevich, was among hundreds of users who exploited a vulnerability in the Nomad platform in August 2022. According to the U.S. extradition request, he personally withdrew tokens worth approximately $2.8 million. Nearly $190 million was stolen in the breach overall.
(Photo: Generated by AI)
Block, who holds Israeli and Russian citizenship, immigrated to Israel in 2017 but reportedly spent much of his time abroad, including in Africa. On April 29, 2025, he changed his surname from Gurevich to Block and received a new passport the following day. On May 1, 2025, two days after changing his name, he was arrested at Ben Gurion Airport before he could board a flight to Russia.
According to the U.S. extradition request, Block identified a vulnerability in the U.S.-based Nomad platform in late July 2022. The platform enables users to transfer cryptocurrencies between different blockchain networks by locking up assets and issuing corresponding tokens in return.
Investigators suspect that Block altered the computer code responsible for verifying that the cryptocurrencies had been locked, causing the system to issue him digital representations of assets without any corresponding deposit.
One of the largest hacks in cryptocurrency history
After confirming that the system had failed to detect the modification, Block withdrew tokens worth approximately $2.8 million from Nomad's wallet on August 1, 2022. He subsequently converted the tokens into various cryptocurrencies and transferred them between digital wallets in an effort to obscure and conceal the origin of the funds.
The Nomad hack was among the largest and most chaotic in cryptocurrency history. After the vulnerability was first exploited, news of it spread on social media, prompting hundreds of users to replicate the attackers' actions. They simply replaced the original wallet address with their own and withdrew funds, without needing any specialized technical knowledge.
According to Nomad, more than 300 wallet addresses participated in the hack, which drained the platform of nearly all its assets.
Research by cryptocurrency exchange Coinbase found that approximately 88% of the addresses involved belonged to "copycats," who collectively stole about $88 million. Two addresses associated with the original attackers withdrew most of the valuable tokens.
Following the breach, Nomad offered to let the hackers keep 10% of the stolen funds without facing prosecution if they returned the remaining 90%. Ultimately, about $36 million was returned.
Demanded a $500,000 'reward'
According to the extradition request, Block contacted Nomad's chief technology officer under a false identity after the hack. He apologized, returned a small portion of the stolen funds and demanded a $500,000 "reward" for discovering the vulnerability.
After Nomad offered him 10% of the stolen assets, he cut off contact.
U.S. prosecutors filed an eight-count indictment against Block in 2023, including charges of computer fraud and money laundering. If convicted, he faces up to 20 years in prison, a substantially longer sentence than he would have faced under Israeli law.
During the legal proceedings, an Israeli district court declared Block eligible for extradition. His appeal to the Supreme Court was rejected in a ruling that established significant legal precedents.
The justices determined that the legal definition of "unauthorized access to computer material" should be interpreted broadly enough to include the exploitation of security vulnerabilities and programming errors.
They also ruled that the public nature of blockchain networks does not preclude money laundering offenses, because the identities of wallet owners remain anonymous and the transfers make it difficult to trace the funds.
Block's subsequent petition for a further hearing before the president of the Supreme Court was also rejected.
Attorney Avi Kronenberg of the International Affairs Department at the State Attorney's Office handled the extradition case.