Hackers breached a contractor for Australia's Department of Defence and stole documents containing information about next-generation spy planes and naval warships, a government official publicly disclosed on Wednesday, the Sydney Morning Herald has reported.

According to the news outlet, Mitchell Clarke, an incident response manager with foreign intelligence collection agency Australian Signals Directorate, acknowledged at the Australian Information Security Association conference that military equipment data and diagrams related to the country's $14 billion Joint Strike Fighter program were included among 30 gigabytes of data stolen by the perpetrator. The data was commercially sensitive, but not classified, the report adds, citing a spokesperson for the Australian Cyber Security Centre.

Clarke also reportedly stated that some of the stolen information related to the U.S. International Traffic in Arms Regulations, which controls the export of defense and military related technologies and verifies the security credentials of firms dealing in U.S. military and defense exports.

The culprit has been nicknamed Alf, which is an allusion to a character from Australian TV soap opera Home and Away (as opposed to the alien creature from 1990s U.S. television). Clarke said that the attacker used a tool called China Chopper, which is apparently popular among Chinese hackers.

Clarke also noted that the breached contractor practiced "sloppy" security, using default logins and passwords.