Optus chairman Paul O’Sullivan has spoken for the first time about the lessons learnt from the cyberattack five weeks ago, which resulted in the details of 10,000 Optus customers being made available on the web.

O’Sullivan, who spoke to Chanticleer before a scheduled appearance at the ASIC annual forum in Sydney on Friday, says the attack forced Optus to rebuild its entire database of 10 million customers, or the equivalent of 20 terabytes of data.