What to Do After a Cyber Attack
March 31, 2025
Cyber attacks are a serious concern for businesses of all sizes. While we all hope it never happens, it's wise to be prepared.
Understanding CIRT Incident Response
As a trusted team of cyber risk management experts, our guide will walk you through what to do if you find your business has been targeted, focusing on the importance of a Computer Incident Response Team (CIRT) approach. We'll cover the essential steps to take to minimise damage and get your operations back on track as swiftly as possible.
Recognising a Cyber Attack
The first step is recognising that an attack has taken place. Sometimes it's obvious, like when your systems are locked down by ransomware. Other times, it's more subtle. Keep an eye out for these warning signs:
- Unusual activity: Are files missing or changed? Are programs running slowly or crashing unexpectedly? Is there strange network traffic?
- Suspicious emails: Have you received phishing emails or emails with dodgy attachments?
- Alerts from security software: Your antivirus or intrusion detection systems might flag suspicious activity. Don't ignore these alerts!
- Login issues: Are you unable to log in to your accounts? Have passwords been changed without your knowledge?
The Importance of a CIRT Approach
A Computer Incident Response Team (CIRT) is a group of individuals within your organisation, or a contracted external team, responsible for handling cyber security incidents. Having a plan in place, and a designated team to execute it, is vital.
A CIRT helps you respond quickly and effectively, minimising the impact of the attack. Without a CIRT, you risk chaos and potentially greater damage.
Key Steps in a CIRT Incident Response
A well-defined incident response plan is essential. Here's a breakdown of the key steps a CIRT should follow:
- Preparation
This stage is all about getting ready before an incident happens. It involves:
- Developing a plan
Create a detailed incident response plan that outlines procedures, roles, and responsibilities. You can find helpful guidance on creating an incident response plan on the National Cyber Security Centre (NCSC) website.
- Identifying your CIRT
Designate the individuals who will be part of the CIRT. This might include IT staff, legal counsel, and public relations personnel.
- Training
Regularly train your CIRT and all employees on cyber security awareness and incident response procedures.
- Gathering resources
Make sure you have the necessary tools and resources available, such as forensic software, communication systems, and backup systems.
- Identification
This is where you detect and confirm that a cyber attack has occurred. It involves:
- Monitoring systems
Continuously monitor your systems for suspicious activity.
- Investigating alerts
Carefully investigate any alerts from your security software or reports of unusual activity.
- Confirming the incident
Once you have enough evidence, confirm that a cyber attack has taken place.
- Containment
The goal of containment is to stop the attack from spreading and limit the damage. This might involve:
- Isolating affected systems
Disconnect infected computers or servers from the network to prevent the malware from spreading.
- Changing passwords
Change passwords for all affected accounts.
- Blocking malicious traffic
Block IP addresses or domains associated with the attack.
- Eradication
This step focuses on removing the malware or other malicious code from your systems. It might involve:
- Deleting infected files
Remove any files that have been infected with malware.
- Uninstalling malicious software
Uninstall any software that has been identified as malicious.
- Restoring from backups
If necessary, restore your systems from clean backups.
- Recovery
Recovery is the process of getting your systems back online and operating normally. This might involve:
- Rebuilding systems
Reinstall operating systems and applications on affected computers.
- Restoring data
Restore data from backups.
- Testing systems
Thoroughly test all systems to ensure they are working properly.
Lessons Learned
After the incident is resolved, it's important to conduct a post-incident review to identify what happened, what went well, and what could be improved. This will help you to prevent similar incidents from happening in the future. This involves:
- Documenting the incident: Create a detailed record of the incident, including the timeline, the impact, and the steps taken to resolve it.
- Analysing the incident: Analyse the incident to identify the root cause and any vulnerabilities that were exploited.
- Updating the incident response plan: Update your incident response plan based on the lessons learned.
Communication is Key
Throughout the incident response process, communication is absolutely vital. Keep your employees, customers, and other stakeholders informed about the situation. Be transparent and provide regular updates. Consider designating a specific person to handle communications during a cyber incident.
Working with External Experts
Depending on the severity and complexity of the attack, you might need to bring in external experts, such as cyber security consultants or forensic investigators. We can provide valuable assistance with incident response, malware analysis, and data recovery.
Long-Term Security
A cyber attack can be a traumatic experience, but it can also be a learning opportunity. Use the experience to strengthen your cyber security posture and prevent future attacks.
To bolster your long-term security, focus on three key areas. First, strengthen your security controls by implementing stronger passwords, enabling multi-factor authentication, and adopting robust security measures like encryption and access controls. Second, invest in comprehensive security awareness training for your employees, ensuring they are well-versed in identifying and responding to potential threats.
Staying Vigilant
Cyber threats are constantly evolving, so it's important to stay vigilant and keep your defences up to date. Regularly review and update your incident response plan, and stay informed about the latest cyber security threats. The NCSC website is a great resource for staying informed about cybersecurity best practices.
Taking Action
Dealing with a cyber attack can be stressful, but by having a plan in place and following a CIRT approach, you can minimise the damage and get your business back on track quickly. Preparation is key. Don't wait until an attack happens to start thinking about incident response. Take action now to protect your business. If you need support, get in touch today.
