Timothy Rabbitt, who was previously managing director of valuation specialist Taylor Byrne, which merged with LandMark White in October, will step in as chief executive while it searches for a permanent replacement for Mr Coonan.
Co-founder Glen White and non-executive director Frank Hardiman are also leaving, effective immediately.
The ASX-listed group has been in a trading halt since last month and Mr Perrett on Monday said while the group was still solvent, the longer the banks withheld work, the “greater the risk to the company”.
He strongly denied speculation the company had been aware of a weakness in its security platforms as far back as 2017, but told The Sydney Morning Herald and The Age there was some “vulnerability” in a previous system that was first installed in 2014.
“We are now probably way ahead of where other valuation firms are in this country with their data security of their networks,” Mr Perrett said.
Mr Coonan joined LandMark White in 2003 as the residential director for its South-East Queensland
offices before being appointed the national residential director in 2012 and chief executive in 2016.
Amid the fallout, the Australian Property Institute (API) is rallying to support the property industry, which was also affected last year by the hacking of Australia’s new electronic property transfer system run by Property Exchange Australia (PEXA).
“Cyber attacks are criminal acts, and recent cyber crime by unknown perpetrators on a range of Australian private and public sector entities demonstrate that any enterprise of any size can fall victim,” API chief executive Amelia Hodge said.
“Our concern is obviously for our members and the clients impacted by these criminal acts. We are here to fully support those impacted in any way we can. We have just under 400 API families directly impacted by the [banks’] suspensions and it is important to move to a business-as-usual state as quickly as possible.”
A spokesman for the ASX has said it was “closely monitoring the situation, including talking to the company”.
Carolyn Cummins is Commercial Property Editor for The Sydney Morning Herald.