The Australian Cyber Security Centre (ACSC), and the overseeing Australian Signals Directorate (ASD), know who attacked the email system of the Australian Parliament House, but they are not saying who it is.
"Attribution is a matter for government, and is made only when in the national interest," it said in response to Senate Estimates Questions on Notice.
Many of the questions were passed off onto the Department of Parliamentary Service (DPS), which revealed earlier this week that it had pulled down and replaced its mobile device management (MDM) system as a result of the attack.
"The attack did not cause an outage of the DPS systems. DPS shut down the MDM system. This action was taken to protect system security while investigation and remediation were undertaken," DPS said.
"To restore services, DPS brought forward the rollout of an advanced mobile services solution that replaced the legacy MDM. The new solution provides greater security and functionality for mobile devices. This rollout was a complex activity and extended the outage experienced by users."
The legacy MDM system remains in use in a limited capacity.
One tidbit ASD did part with was agreeing that the attacker was unsophisticated and that the ACSC was involved in "searching for any potential implants" in the APH Exchange server.
An unsophisticated attack would have had a higher than expected chance of succeeding, thanks to the lack of 2FA.
"Before users came back on line after this incident, they were asked to implement new security controls to access APH emails via mobile handsets -- namely multi-factor authentication," Senator Kimberley Kitching said in a question.
"In the course of providing cybersecurity advice and assistance to DPS following the incident, the ACSC provided broad advice on security controls," the ASD said.
ASD said there was no "specific threat" that led to the introduction of 2FA, and instead pointed to its Essential Eight advice first published in 2017.
DPS said earlier this week it had seen no evidence of any email accounts being compromised due to the attack, and the attack had nothing to do with recent Exchange vulnerabilities.
In another answer, ASD said no code review has been completed on the systems of the Australian Electoral Commission, but it has "conducted a vulnerability assessment and partnered with the AEC to conduct multiple uplift activities on the AEC network."