Cybersecurity specialists have warned Medibank still has a lot of work to put in to remediate its online defences, as investors poured into the stock, on the basis that it had successfully ridden out the negative publicity garnered from last year’s disastrous data breach.

Medibank’s shares have risen over nine per cent since the health insurer announced its half-yearly results on Thursday, marking the first reporting event since the company was consumed by controversy.