Groups similar to ShinyHunters – believed to be an English-speaking gang – have in the past been linked to swatting incidents, and even petrol bomb attacks against law enforcement officers and rivals.
Swatting is a phenomenon so-called because perpetrators make calls that prompt armed police units – called Swat teams in the US – to swoop in on victims.
The group claims it breached FBI systems on Monday and later posted details of the attack on its darknet site.
The FBI has not responded to requests for comment.
However, on Wednesday the agency acknowledged the breach – saying it was “aggressively investigating” how it occurred.
For Michael McPherson, a former FBI agent who is now senior vice president of security operations at cyber firm ReliaQuest, the hack presents “a security threat which cuts to the core of agent safety, particularly their families”.
He says agents understand the “inherent risks” that come with the job.
“But this incident reportedly includes personal data such as home addresses and contact information, which could expose family members who are normally insulated from the threats associated with such a career,” McPherson says.
ShinyHunters shared samples of the alleged stolen data with reporters, along with an extortion demand.
The samples appear genuine and include names, addresses, phone numbers, badge numbers, job titles and information about spouses.
The records appear to relate to thousands of agents, including senior officials such as deputy directors.
The criminals also appear to possess highly sensitive medical information relating to thousands of special agents.
BBC News has seen samples of stolen “fitness-for-work” medical examinations containing information such as blood and urine test results, along with doctors’ notes mentioning conditions including a “shellfish and banana allergy”.
Agents’ full names and addresses, as well as references to medical issues including “blood in the urine” and “high cholesterol” are now in the criminals’ hands.
Cynthia Kaiser, who was the Deputy Director of Cyber at the FBI and now leads the Research Centre at Halcyon says ShinyHunters appear to already have lost control of some of the data which is circulating in various online groups of cyber researchers and could lead to harm even before the main tranche is published.
“A lot of the damage may already be done, and as we have seen in past FBI data breaches, that information continues to circulate the dark web years later,” she said.
There are also concerns about the breach’s national security implications, such as staff becoming targets for recruitment efforts by hostile foreign intelligence services.
