A man accused of launching cyber attacks against two of the UK’s largest banks has appeared in court.
Daniel Kaye allegedly targeted Lloyds Banking Group and Barclays in January.
The three-day attack prevented Lloyds, Halifax and Bank of Scotland customers using some online accounts, after the banks refused to pay a ransom.
Mr Kaye, 29, of Egham, Surrey, was extradited from Germany on Wednesday and appeared before Westminster magistrates earlier.
The attack featured distributed denial of service assaults – where multiple infected computers bombard a system to overwhelm its security and access information.
He is said to have developed malicious software enabling him to take control of computers all over the world – known as creating a botnet.
It is estimated it cost Lloyds £190,000 to get its internet services back online, while Barclays paid about £146,000 to get its systems fully up and running again.
In one email to a potential client, Mr Kaye allegedly boasted he had between 555,000 and 1.5 million computers in his botnet, the court heard.
He faces nine charges under the Computer Misuse Act, two of blackmail and one of possession of criminal property.
One of the charges also relates to an allegation he “endangered human welfare” by carrying out a cyber attack against Lonestar MTN, the largest internet provider in Liberia, west Africa.
Mr Kaye, who has British and Israeli citizenship, was extradited under a European Arrest Warrant following an investigation involving the National Crime Agency’s German counterpart the Bundeskriminalamt.
Listing his case for a plea and case management hearing on 28 September at Blackfriars Crown Court, District Judge Tan Ikram remanded him in custody until that date.
A Lloyds spokeswoman said the January attack was “successfully defended” and no customer details or accounts were compromised.