BAE reversal came after Homeland Security came calling

BAE Systems' inaccurate claim of stopping a major cyberattack against a large hedge fund got the attention of the U.S. Department of Homeland Security, CNBC has learned.

A Homeland Security official said the department, through its National Cybersecurity Communications Integration Center, contacted BAE Systems after officials saw a story on CNBC about the purported attack. "We checked with the FBI and Secret Service to see if they had anything on this, and then we reached out directly to BAE to ask for more information," the official said. "Our operational people talked to their operational people."

Department of Homeland Security employees work inside the National Cybersecurity and Communications Integration Center in Arlington, Va.
Kevin Lamarque | Reuters

In an interview with CNBC that aired on June 19, Paul Henninger, global product director for BAE Systems Applied Intelligence, told CNBC that his company had found and stopped a malicious cyber-intrusion into a hedge fund client that he declined to identify. It was in the wake of that report that Homeland Security contacted BAE Systems, the official said.

But on July 2, BAE Systems spokesperson Natasha Davies said that the attack that Henninger had described as a real event had in fact been a "scenario" used by cyberexperts inside BAE Systems.

Read MoreBAE says it 'incorrectly presented' cyberattack

The Homeland Security official said BAE Systems was ultimately unable to provide any information about the purported attack, even though a senior executive with BAE Applied Intelligence had given a televised interview about it. "Their operational people had to figure out what their spokespeople were talking about," the Homeland Security official said.

Around the same time that the company publicly acknowledged the mistake, the official said, BAE Systems also admitted to the U.S. government that it could not substantiate its own announcement. The DHS official said the department would not follow up any further with BAE now that the report has turned out to be inaccurate.

BAE 'incorrectly presented' cyberattack
BAE 'incorrectly presented' cyberattack

"This is a realm in which a lot of people are trying to make a name for themselves and they're very eager to lean forward and say they've stopped this attack or that attack," the Homeland Security official said.

Read MoreCrack the code: Best hackers come from these universities

BAE Systems spokeswoman Morag Lucey declined to discuss the contact from Homeland Security. "We realized after the broadcast went out that our normal internal procedures had not been followed and also received a number of inquiries from stakeholders about the story—when we looked into this, we realized the error," she said. "Once we had a reasonable level of certainty that the information we had provided was inaccurate, we acted as quickly as possible. We have engaged with all relevant stakeholders but do not comment on communications with specific authorities."

BAE Systems declined to provide CNBC with a copy of the scenario it says was the basis for the inaccurate announcement. "We don't actually have something that's physically available to give to somebody," Lucey said. Asked whether the scenario is formatted as lines of code, PowerPoint or in some other document, Lucey said, "it's a collection of all different types of information."

BAE Systems also declined to make Henninger available for a follow-up interview or to discuss his status with the company. Previously, BAE has said Henninger is "taking some time away from the business."

—By CNBC's Eamon Javers. Follow him on Twitter: