In a statement posted with links to the data on the upload site Pastebin, the hackers said they had taken the Apple data from a much larger database of more than 12 million users' personal information stored on an FBI computer.
In their message, the hackers say they used a vulnerability in Java to access the data on an FBI Dell laptop in March of this year. They say the database included not only the UDIDs, but also "user names, name of device, type of device, Apple Push Notification Service tokens, zipcodes, cellphone numbers, addresses, etc."
It is not clear whether the UDIDs are real. The FBI said on Tuesday there was "no evidence" to support claims that Anonymous lifted a file from a laptop with identification numbers for more than 12 million Apple products.
Anonymous argues that the massive dump of users' personal information is designed raise awareness of the FBI's alleged gadget-tracking methodologies. "We will probably see their damage control teams going hard lobbying media with bullshits to discredit this," the statement reads. "But well, whatever, at least we tried and eventually, looking at the massive number of devices concerned, someone should care about it."