Websites were shut down, public servants received threatening phone calls and pornography was plastered across Kevin Rudd's home page in a major cyber protest against government plans to filter the internet.
The government's Cyber Security Operations Centre discovered the attack was coming on February 5 but was unable to stop the parliament house website going offline and Prime Minister Rudd's site becoming home to "Operation Titstorm".
Internet protest group Anonymous, known for its regular attacks on Scientology websites, was behind the actions which were led by a so-called denial of service charge on www.aph.gov.au.
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Just after 8am (AEDT) on Wednesday the parliament's website was hit by 7.5 million requests for communication per second, Parliamentary Services Secretary Alan Thompson told AAP.
"We had some advice in the lead-up to today there was going to be some cyber attack," Mr Thompson said.
Senior staff inside the department also had their emails spammed "in spectacular ways".
High-ranking public servants were telephoned as part of the attack.
"Aggressive but anonymous phone calls are being made to the offices of various parliament house executives," an internal parliamentary services email obtained by AAP said.
While the initial attack was stopped about 9am (AEDT) on Wednesday, further attacks continued throughout the day.
The proposed internet filter would crack down on pornography.
The Department of Broadband, Communications and the Digital Economy's website also experienced a degraded service, a spokesman from the Attorney-General's Department said.
The spokesman said government agencies identified as potential targets by the group had been briefed on the threat, and were provided with strategies to help stop a hacking attempt.
At 1.30pm (AEDT) the spokesman said the Australian Parliament House website was back online, however, at 2.10pm (AEDT) it was again inaccessible.
Parliament House's fax system was also hit with spam.
Defence Minister John Faulkner said the Cyber Security Operations Centre remained on watch.
"As inquiries are ongoing it would be inappropriate for me to comment further," Senator Faulkner's spokesman said.
