BlackCat claimed a seven terabyte data theft from Barts Health NHS Trust

The ALPHV/BlackCat ransomware group listed Barts Health NHS Trust on its dark web extortion site on June 30, 2023, claiming to have taken seven terabytes of data. The gang described the haul as the largest leak from a healthcare system in the United Kingdom and gave the trust three days to make contact before it would begin publishing.

Barts Health is one of the largest NHS trusts in England. It runs hospitals in east London including The Royal London, St Bartholomew's, Whipps Cross, Newham and Mile End, and serves a population of around 2.5 million.

According to the listing, the stolen files included confidential citizen documents, personal information on employees and clinicians such as National Insurance numbers, and financial material covering credit card details, accounting and loan records and insurance agreements. None of the claims were independently verified.

A trust spokesperson said Barts Health was aware of the allegations and was investigating them as a matter of urgency. No service disruption was reported, and the leak site entry made no mention of a decryption key, which commentators read as a sign that data had been copied rather than systems encrypted.

Accounts of the size of the theft differed. Cyber Security Hub and IBTimes UK reported the gang's claim as seven terabytes, while Tech Monitor put it at more than 70 terabytes. As of early July 2023, the trust had not confirmed what, if anything, had been taken, and figures citing 2.5 million patients reflected the population Barts serves rather than a verified victim count.