Australian firm SSKB Strata Management has been victim of a ransomware attack, after cyber criminals purportedly stole 200 GB of data from the company.

A cyber criminal has told SSKB, which has offices in Queensland and Melbourne as well as on the Gold Coast, that if it doesn’t pay a ransom in eight days, data will be released.

The threat actors are demanding $300,000 in ransom payments, worth about $460,000 in Australian currency, after posting a “proof of hack” on a Tor site on the dark web.

A notice on the strata management company’s website said “some phone and technical issues” are affecting its operating systems, suggesting that the company’s phone lines are down.

The attackers are said to have posted a ransom demand and claimed to have stolen 200GB of data from SSKB, including construction project data, customer financial information, management correspondence, contracts, and agreements.

SSKB disclosed the attack with CEO Daniel Herbert saying a third-party had “gained unauthorised access to SSKB’s IT environment, downloaded some information and posted a ransom demand on the dark web.”

According to SSKB it’s called in an external forensics company, and notified the Office of the Australian Information Commissioner (OAIC) and the Australian Cyber Security Centre (ACSC).

In a notification Herbert wrote “We are working as swiftly as possible to determine what, if any, personal or sensitive information may be contained in the dataset that was downloaded.”

“Should we identify this is the case, we will work to meet our obligations and notify any individuals at risk as soon as we can.” Herbert wrote.

The SSKB hack is the latest in a string of cyber assults hitting high-profile Australian companies that included recent data breaches at Optus, Medibank and Australian Clinical Labs pathology services.

The SSKB hack may include identifying information about the strata management firm’s customers, including names, email addresses, and phone numbers.