Authorities are investigating after a map claiming to show the addresses of thousands of firearms owners in the UK was published online.
Gun-selling site Guntrader announced a data breach affecting more than 100,000 customers in July.
This week, reports emerged that an animal rights activist blog had published the information.
The group had formatted the data so it could be easily imported into mapping software to show individual homes.
The National Crime Agency, which has been investigating the data breach and its fallout, said it “is aware that information has been published online as a result of a recent data breach which impacted Guntrader”.
“We are working closely with the South West Regional Cyber Crime Unit, who are leading the criminal investigation, to support the organisation and manage any risk,” it said.
And data regulator the Information Commissioner’s Office also said it was “aware of a potential change in the Guntrader Ltd incident”, adding “we will be making inquiries”.
In its initial statement in July, Guntrader said that no information about the “location of firearms was taken”, but acknowledged that user names and addresses had been.
The company said it had nothing to add in response to the latest development “beyond saying that we continue to work with the relevant authorities to mitigate the impact of this data theft”.
‘Remain vigilant’
The existence of the new map format was first reported by tech news site The Register, which characterised it as the “worst-case scenario” following the initial hack.
In July, one gun owner told the BBC he feared that the leak could put his family in danger, particularly from criminals.
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While the leaked data had previously been published on the dark web, the latest development was published online and easily accessible to anyone, and reformatted so that it could be imported easily into Google Maps.
Doing so would give “precise geographic co-ordinates” for many – but not all – of the more than 100,000 people in the database, The Register suggested.
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Firearms security
Firearms are tightly controlled in the UK, with a licence required for rifles and shotguns, mainly used legally by farmers or for hunting.
The law requires licence holders to store firearms and ammunition securely so they cannot be taken by anyone else.
The British Association for Shooting and Conservation recommends using a purpose-built gun cabinet bolted to a solid wall to do so.
Keys should be kept securely so that only the owner and no-one else – not even other members of the family – can access them, it says, possibly in a small combination safe.
The government also has a guide to firearms security, outlining best practices.
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“The Guntrader data leak represents not only a serious breach of privacy – but also poses a physical threat,” said Attila Tomaschek, of the ProPrivacy group.
The animal rights activists posting the data claimed without any accompanying evidence that the “vast majority” of gun owners kill animals “and sometimes even go on to kill humans”.
Mr Tomaschek said the group’s post amounted to “calling on others to confront the victims of the breach”.
“Those with firearms must now remain vigilant as it may only be a matter of time before the information is used by opportunistic criminals looking for weapons,” he warned.
In addition to concerns about harassment or theft, some of the data may not be accurate.
“Some of the data is reportedly over five years old, meaning that a number of the addresses likely no longer even belong to the gun owners included in the leak, putting an even greater number of individuals at risk,” Mr Tomaschek warned.