What to Do in the First 24 Hours After You’ve Been Breached

Whether you view a data breach as your worst nightmare, or simply an inevitable occurrence for the average organisation, knowing what to do and how to respond when it happens to your organisation is critical. A well-executed response contains a crisis and stops it from snowballing, as well as helping you navigate your organisation—and your suppliers and customers—through any follow-on analysis or potential post-incident investigations. 

1. Validation and triage

Your first steps should always be to establish whether an incident has actually occurred. Even a well-informed employee-base, and a suite of managed and tuned security tools will still generate false positives so perform triage and review your logs to identify what, if any, device, system, or data asset is at risk or has already been compromised. Realise that while you are dealing with a current threat, intruders may have been present in your system for months before you identified the incident. It’s critical therefore to look across infrastructure, applications, and cloud services to establish the full reach of their activity and access. 

If you find clear evidence of a breach you may need to take a range of actions such as issuing an immediate internal notice to employees at risk, removing access to compromised systems for non-essential users, or isolating the environment to limit propagation of the threat.

As the first hour comes to a close, it’s time to take the information you have to your internal stakeholders and formulate your response.

2. Plan, Test, and Prepare

Your breach response plan will look different depending on the parameters of the attack to which you are responding. If you are the target of a ransomware attack, you are likely to know the extent and reach relatively soon, because the threat actor will make their success clear to demand their ransom payment. However, other attackers may be more covert, if they are prioritising espionage for their data exfiltration, or if they are using a high-value zero-day vulnerability motivated by longer-term plans within your systems. These more sophisticated attacks often originate from state-sponsored actors. Bear in mind that these attacks are often not ad hoc “smash and grab” data theft opportunities.  You need to behave as though the threat actor is still inside your systems and be aware that they could be monitoring your actions and pivoting to evade further detection. 

I recommend that before “Discovery Day / D-Day” you have a plan of action devised, documented, and tested for a range of scenarios so that you can turn to these during your response actions. Once your stakeholders are aware of the situation, you will be under great pressure to resolve the incident whilst maintaining business-as-usual. 

One of my primary recommendations is to take detailed notes or records of not just the way the situation progresses, but also the decisions you take. Balancing security remediation with business continuity can be highly stressful, and can put the investigating team under added pressure to avoid drastic measures (even when they may be appropriate). Keeping records of the context surrounding your decisions helps you adjust your plans for future events, but also helps you justify the entire process and your decisions when the incident is over. 

3. Communicate

Once remediation is in hand, you may have to contact customers and partners and may also have a legal responsibility in certain territories to tell those impacted directly, as well as the necessary regulators, what has happened. 

This is a key and potentially career-defining moment, so working closely with your comms team to ensure the messaging is right is important—you have to be honest and constructive, and ultimately helpful. Although the general public may be jaded to cyber attacks, don’t be lulled into thinking no one will care. Regulators and the industry at large will measure your response, so make sure you understand your legal and regulatory obligations for reporting, as well as taking advice from your PR colleagues on how best to communicate.

4. Go home

Once you reach the stage where the incident is under control and communications have been made, take a break. Most cyber attacks take place out of hours, and you and your team may have worked a full day before the incident was identified. The most important task you can undertake now is to take a step back, go home, and rest. Tired people are more likely to make poor decisions. If you work as part of an international team, give some thought in advance to how you can best use your team across time zones to take a “follow-the-sun” approach to both remediating the incident and ongoing communications with customers if necessary.

What’s next?

What happens next is difficult to say. You may be tasked with mitigating and patching additional vulnerabilities, recovering data from backup systems and services, or preparing for further potential attacks because, once an incident goes public, you may have an even larger target on your back. 

Once the incident is under control, you have an opportunity to put your experience to use. Consider capturing the event in a case study designed to access additional budget if the need can now be illustrated, or draw on the experience to formulate new incident response plans.  Certainly, sharing information and insights is one of our best weapons for combating cyber threats, and if you’ve handled it following these or similar guidelines there’s value in sharing your experience with peers to help them respond to the next incident.