Defence added fresh safeguards in a bid to plug leaks after "highly sensitive" intelligence was allegedly disclosed by a junior defence bureaucrat on an online forum.
Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
But Australia's former Army chief Peter Leahy said there was simply no way to stop staff who are determined to leak from the Department of Defence.
Michael Scerba, now 24, is accused of downloading a secret Defence Intelligence Organisation report, burning it to a disc, taking it home, and uploading it to image sharing website 4chan in October 2012.
A Defence spokesperson said that it has since reviewed its ICT systems and added new safeguards in the wake of the incident.
Defence declined to comment on the specific security safeguards it had introduced.
The spokesperson said its graduates were robustly vetted by the Australian Government Security Vetting Agency and undertook training in classified document handling, code of conduct, and security and social media awareness.
But, now retired Lieutenant General Peter Leahy, who was chief of army between 2002 and 2008, has warned that vetting of staff can only do so much to ensure they will not spread government secrets illegally.
"They can't be stopped, and they can't be stopped because sadly we can't rely on the integrity of individuals across the board," he said.
While not commenting on any specific case, Professor Leahy, now the director of the University of Canberra's National Security Institute, said it was difficult to prevent leaks, saying a lot of faith was placed in the integrity of staff.
"If someone chooses to go against the commitment and oath that they've made, you just can't stop them, it's their choice," he said.
Scerba, then a 21-year-old Defence graduate, allegedly accessed the Secret Defence Security Network to download the DIO intelligence assessment in October 2012.
He is accused of posting the first two pages to online image-sharing forum 4chan. The first post was said to have included the comment "Julian Assange is my hero".
Prosecutors say a former Defence Signals Directorate officer stumbled onto the post "fortuitously", before alerting Defence.
Later comments are said to have allowed the Australian Federal Police to track an IP address to Scerba's home in Canberra's south. They forensically examined his study computer, which had no password, and found traces of the DIO report, prosecutors said. The 4chan website was one of the most visited, according to court documents.
The contents of the leaked report are the subject of strict secrecy provisions in the current ACT Supreme Court proceedings.
Commonwealth prosecutors have alleged the document directly revealed the identity of intelligence sources, gathering methods, and classified aspects of strategic partnerships between Australia and foreign countries.
The document was meant for the "Five Eyes" intelligence alliance involving Australia and its top allies.
Scerba possessed a secret, or negative vetting level one, clearance, and had been with the department for about eight months.
Mr Leahy said that vetting could only provide so much assurance that staff would do the right thing.
"The vetting process is extensive and expensive, but if someone chooses to lie during the vetting process and can cover up their lie, or even after the vetting process, chooses to act in an illegal manner, there's not much you can do about it," he said.
