Don't let their party shirts and relaxed demeanour fool you - for Defence cybersecurity experts, the ADF Cyber Skills Challenge is serious business.
Held from December 1 to 5, more than 200 people from Defence, government and industry took over Canberra's QT Hotel ballroom for the ADF Cyber Skills Association's annual cybersecurity conference and 'capture the flag' (CTF) competition.
Many more dialled in from overseas to solve more than 100 increasingly complex cybersecurity challenges, such as finding clues using open-source intelligence and digital forensics of a computer's memory to uncover malicious code.
The Cyber Skills Challenge is the culmination of three smaller CTF activities delivered by the Cyber Skills Association throughout the year.
During October and November, the association holds a Services Cup, selecting a representative team from each of its Navy, Army, Air Force and Australian Public Service cohorts to compete in the Cyber Skills Challenge.
This year, Army's representative team solved the most problems to earn top points and take first place, followed by Cyber Operations Command - Vietnam and the Australian Industry team.
Corporal Chris Green is the Army service representative for the ADF Cyber Skills Association. He said complex problems can take teams hours to solve and working through the night was common.
"All the easy challenges get mopped up early on," Corporal Green said.
In previous years, participants had to decode dial tones to find hidden information about an individual's call history.
"That had us pulling our hair out," Corporal Green said.
'If that's how criminals are targeting consumers, it could also be the same way criminals target Defence personnel, so we need to look at it from that perspective.'
Navy Warrant Officer Andrew Speirs has participated in the event six times.
"When a team yells out, 'I've solved it', there's a bit of a buzz and you watch the leader board to see the scores change," Warrant Officer Speirs said.
"Everyone is amazed at how they solved the question, especially when it can take days to find the answer."
The CTF followed two days of industry presentations and workshops.
The NSW Department of Communities and Justice provided insight into dark web trends and finding indicators of nefarious online activity.
Commonwealth Bank gave a presentation on keeping customer data secure.
Warrant Officer Speirs said criminals valued data, which could be sold, over dollars.
"If that's how criminals are targeting consumers, it could also be the same way criminals target Defence personnel, so we need to look at it from that perspective," Warrant Officer Speirs said.
For ADF Cyber Skills Association Vice Captain Leading Seaman Carlos Chua-Lao, the chance to learn new skills and see old friends was what kept him coming back.
"Cyber is a small community but we're all spread across the country," Leading Seaman Chua-Lao said.
"It's a time to test our skills as well, to see how we're tracking.
"I struggled with some of the challenges in my first few years, but I see something similar now and I can crack it - so seeing that growth is really good as well."
