You’ve Just Discovered A Data Breach. Go! [If You Know How.]

Dane Meah
March 9, 2018


TODAY, around the country, there may be a very worried IT Manager, CIO or business leader coming to the realisation that they have fallen victim to a cyber attack resulting in a data breach. However, under the revised Notifiable Data Breach legislation, this incident has a whole new level of stress and complexity.

Now, before I go on, enough has been written about the “Mandatory Disclosure” Notifiable Data Breach legislation, the stiff penalties, obligations and what should be considered a breach. But what must you ACTUALLY DO if you come to realise that like many a company before, you have inadvertently lost sensitive public data?

The reality is most breaches are NOT known about or fully understood for well over 6 months. Perhaps it started with a server “humming” at an unusual frequency, or perhaps your firewall blocked a few outbound connection attempts, but you thought nothing of it. Small pieces of telemetry which on their own may not raise the alarm that could have prevented the breach from occurring.

So, with the new laws, what should you do first? Which business stakeholders should you inform, without causing mass panic? Are there any actions you should take from a technical perspective immediately to mitigate further damage?

We’ve seen scenarios where organisations have had a knee-jerk reaction which later turned out to be the wrong play.

The more organised amongst you will have clearly defined AND practiced Incident Response Plan’s (IRP) that consider more than just IT in the case of an incident. In that regard, a data breach is no different and should be treated like any other incident, with one crucial difference – under the new legislation, you must effectively air your dirty laundry and disclose what, why, when and how it happened!

A Notifiable Data Breach is one that results in the loss of confidential third-party data, be it names, contact details, date of birth, etc. (PII), Credit Card (PCI), or other information such as health records or financial records. Once a Breach has occurred you must let those affected and the government know. Whilst the Government will not necessarily publicise that a breach has occurred, depending on the number of people affected, it may be more practical to publicly announce your breach to ensure your customers have had ample opportunity to be informed about what has happened.


Baker McKenzie Partner, Patrick Fair, prepared an excellent flow diagram explaining when and in what scenarios you should take action, and what action you should take.


First, it’s critical you prevent further loss of data by rapidly detecting and isolating the attack that led to the breach. This can be a time consuming and costly exercise, especially without the specialised knowledge, skills, and tools for this.

We often hear of scenarios where the threat was removed, only for it to resurface again. Often it makes sense to leverage a specialised Incident Response Service for this, but at the very least you should have a clearly defined Incident Response Plan.

Infotrust uses the CrowdStrike Falcon to threat hunt and identify whether a malicious actor is still operating in your environment, allowing for appropriate actions to be taken to block this and where applicable close the back door that allowed the threat in the first place.


These tools can also provide significant insights into how the attacker gained its entry so that preventative measures can be taken to ensure an immediate repeated breach doesn’t occur, which we commonly see after a breach has been detected.


Depending on the nature of the data that was lost, an impact analysis should be performed to consider what are the potential consequences of the data that was lost and potential steps that could be taken to mitigate harm (e.g. temporarily elevate authentication requirements or force password resets).


There’s a lot that you can do which we cover in more detail in this eBook “Guide to Notifiable Data Breach Scheme”. Other good places to start are looking at the Australian Signals Directorate Essential 8, which look at the security controls and best practices for mitigating a cyber incident.


Whilst the old saying “hindsight is 20/20” is very pertinent following a breach, it’s equally fairly predictable how most attack’s find their way through a company’s defences (or lack thereof). Whether it be a ‘human error’ exposed AWS S3 bucket or open firewall port, or infection of an Endpoint resulting from a zero-day attack via the email or web channel, there are things that ought to have been done that enhance your People, Process and Technology security posture.

At Infotrust, we also highly recommend conducting a Cyber Security Gap Assessment aligned to a framework such as NIST or ISO27001 to support in determining where are the gaps you should be prioritising your Cyber Security budget on.