The site is currently pulled down, and Treasury officials released a statement late on 29 June, concluding that the breach was the work of a hacker.
"It has been established that the GST Assist site was improperly accessed and data extracted by a hacker," reads the statement. "This site is separately located with an external service provider under contract to the GST Start-Up Office. It has no connection to any Treasury or Australian Tax Office sites."
The man, who contacted the ABC on the morning of 29 June with details of the breach, allegedly "discovered" the breach during a visit to the site. Via email, he alerted over 10,000 people whose financial details were on the site that their information was compromised by a security flaw. Business owners who had registered their business with Treasury's GST Assist site received the following message from "K2", the online name of the man, and the details he discovered on the site:
''Dear Xxxx Xxxx.
''The web site at http://www.gstassist.gov.au/ has a serious security flaw which permits access to your private details, including your bank account information...''Treasury has issued a statement confirming that the GST Assist site has been shut down while investigations are underway. Treasury has confirmed that the database holding the information contained "no other bank account details, no general taxpayer information, no ABN numbers, no taxpayer records, and no general Treasury records."
Security analysts speculate that the breach did not involve a high degree of skill, instead taking advantage of what one industry source described as a "first year computing mistake" on the part of the site's builders. Another industry insider added that Kelly may well have tried a relatively simple trick of appending a long string to a URL, ostensibly to "see what happens".
Hacking group 2600.org.au has posted a resource page on its website with information on how such attacks occur.
This is the third serious privacy breach involving the ATO in the recent months. The Office was called to task over the sale of details provided by Australian Business Number applicants, as well as a decision to address GST information letters individually to all entrants on the electoral roll. In both instances, the ATO was found to be in breach of the Privacy Act.