A hacker is threatening to leak 106GB of data allegedly stolen from Spanish telecommunications company Telefónica in a breach that the company did not acknowledge.
The threat actor has leaked a 2.6GB archive that unpacks into five gigabytes of data with a little over 20,000 files to prove that the breach occurred.
Partial leak with data allegedly stolen from Telefónica
The breach allegedly occurred on May 30 and the hacker claims they had 12 hours of uninterrupted data exfiltration before defenders revoked access.
The hacker claiming responsibility for the attack is known as "Rey" and is a member of the Hellcat Ransomware group - responsible for another breach at Telefónica in January through an internal Jira development and ticketing server.
Rey told BleepingComputer that they exfiltrated 385,311 files totaling 106.3GB of internal communications (e.g. tickets, emails), purchase orders, internal logs, customer records, and employee data.
They also said that the May 30 breach was possible because of a Jira misconfiguration after the company dealt with the previous compromise.
BleepingComputer tried on multiple occasions since June 3rd to reach out to Telefónica over email. We also contacted several C-suite employees but received no acknowledgment of the May 30 breach.
The only response we received came from a Telefónica O2 employee, who dismissed the alleged incident as an extortion attempt using outdated information from a previously known incident.
Telefónica O2 is the Spanish company’s brand for its telecommunications businesses in the U.K. and Germany.
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