Contractor arrested over Sydney data hack

A Sydney software contractor has been arrested over the unauthorised access of a more than 170,000 data records which were uploaded onto the dark web and internet.

Strike Force Vide was set up in June to investigate the hacking of an Australian-based company's main database and document store.

"With the assistance of company staff, investigations identified that unauthorised access was gained into the company's database and more than 170,000 data records including personal information and valuation documents were uploaded to the dark web and the internet," police said in a statement.

The 49-year-old male software contractor was arrested outside a business in Sydney's CBD at 8am on Wednesday.

Cybercrime Squad detectives then raided a home at Rozelle and a business data centre at Ultimo.

The man has been taken to Surry Hills Police Station, where he is expected to be charged.