A major US telecommunications company discovered a foreign implant in a server back in August, according to a new report by Bloomberg. It’s the first time a source has decided to go on the record to corroborate the claims made in a report by the publication last week, alleging that Chinese spies were able to compromise servers belonging to 30 of the US’s top tech companies through the use of hardware manipulations.

The implant was reportedly built into a server’s Ethernet port, giving hackers a back door into the telecommunications company’s computer networks. In Bloomberg’s discussions with Yossi Appleboum, the security professional who first identified the manipulation, no technicians working for the company knew what kind of data was flowing through the compromised server. That server was one of many in the facility that was created by Supermicro, the same Chinese manufacturer that supplied servers to the tech companies in last week’s original report.

That server was one of many in the facility created by Supermicro

The initial Bloomberg report has come under heavy fire for its use of anonymous sourcing and its lack of independently verifiable details. Both Amazon and Apple have pushed back against the report with unusually thorough and detailed denials, leaving many security experts questioning the reporter’s sources. One of Bloomberg’s contacts, Joe Fitzpatrick, went on a podcast Monday explaining that he was uncomfortable with the story and was unsure whether it was entirely accurate.

The latest report declines to name the major telecommunications company in question due to a non-disclosure agreement signed between Yossi and the telecom. On Monday, Apple sent a letter to both House and Senate Commerce committees kicking up the heat on the device maker’s denials and announcing that the company would be willing to send someone up to the Hill to brief staffers.