A cyber attack can strike without warning, causing devastating data breaches, operational downtime, financial losses, and erosion of customer trust. Whether it’s ransomware locking your files, phishing attacks tricking employees, DDoS overloads, or hackers exploiting vulnerabilities to gain unauthorized access, the actions taken in the first 24 hours of a security incident determine how much damage occurs and how quickly you recover.
Cybercriminals and hackers constantly scan for weak defenses, aiming to steal sensitive data, personal information, credit card numbers, email addresses, or confidential records. A swift, structured incident response can mitigate the impact, preserve evidence for forensics, and prevent further exploitation.
This step-by-step guide outlines critical actions to take immediately after detecting a cyberattack, helping organizations strengthen cyber-security, information-security, IT-security, and computer-security while complying with regulations and reducing cyber risk.
1. Confirm the Incident and Stay Calm
First, verify the security breach. Look for signs like unusual network activity, encrypted files (common in ransomware), unexpected alerts, or reports of social engineering or phishing attacks.
Stay calm—panic leads to mistakes that cyber criminals can exploit. Assign a single incident lead (often the Chief Information Security Officer or a security professional) to coordinate response and control communications. Document everything: timestamps, affected systems, and initial observations. This supports later forensics, threat intelligence, and potential law enforcement involvement.
2. Isolate Affected Systems Immediately
Containment is priority one to stop malicious spread across your network security.
- Disconnect infected endpoints and servers from the internet and internal networks.
- Disable user accounts that may have been compromised.
- Block suspicious IPs, domains, or firewalls rules linked to the adversaries.
- Suspend affected cloud services or third-party integrations.
Do not power off systems without consulting security experts—this could destroy valuable forensics evidence needed to understand how hackers gained entry.
3. Activate Your Incident Response Plan
If your organization has a formal incident response plan, activate it immediately. This plan defines roles, escalation paths, and communication protocols for security incidents.
Key team members to involve:
- Internal cyber-security and IT teams
- Senior management and Chief Information leadership
- Legal/compliance officers
- External security services or cyber defense consultants
Without a plan, designate a lead to orchestrate remediation and ensure coordinated cyber defense.
4. Preserve Evidence for Investigation
Preserve digital evidence to enable thorough forensics analysis, identify the attack vector, and support insurance claims or law enforcement reporting.
- Secure and backup system logs, network security traffic, and access records.
- Create forensic images of affected systems.
- Document all response actions with precise timestamps.
- Protect evidence from tampering.
Proper handling helps trace how cybercriminals exploited vulnerabilities, prevents recurrence, and strengthens future security measures.
5. Assess the Scope and Impact of the Attack
Quickly evaluate the breach to prioritize remediation:
- Which systems, endpoints, and data types were impacted?
- Was sensitive information, personal information, or card informationleaked or at risk of identity theft?
- Is the attack ongoing, or contained?
- How severely are business operations disrupted?
An initial assessment guides resource allocation and determines if sensitive data exposure triggers mandatory breach notifications.
6. Change Credentials and Secure Access
If credentials are suspected compromised, act fast to block unauthorized access:
- Force password resets for all potentially affected accounts.
- Prioritize privileged/administrator accounts, email, remote access, and cloud platforms.
- Enable or enforce multi-factor authentication (MFA) immediately.
- Revoke and regenerate API keys, tokens, or sessions.
Strong access control and encryption are among the fastest ways to prevent hackers from re-entering your information systems.
7. Communicate Internally With Care
Inform employees calmly and factually to maintain order and boost security awareness:
- Share what is known about the cyber threat.
- Provide clear instructions (e.g., avoid suspicious links, report anomalies).
- Prohibit speculation or external discussion.
Controlled internal communication prevents panic and reduces chances of further social engineering success.
8. Engage External Security Experts if Needed
If the attack exceeds internal capabilities, bring in specialized security professionals or incident response firms immediately. They provide:
- Threat containment and eradication
- Advanced forensics and threat intelligence
- Secure system recovery
- Guidance on regulatory reporting and cyber insurance
Early expert involvement often dramatically reduces downtime and long-term cyber risk.
9. Review Legal and Regulatory Obligations
Many jurisdictions and industries require timely notification after a data breach involving personal information or sensitive data.
Consult legal counsel on:
- Mandatory reporting to regulators, affected individuals, or partners
- Compliance with GDPR, CCPA, HIPAA, or PCI-DSS
- Cyber insurance policy requirements
- Potential law enforcement or national security notifications
Non-compliance can lead to hefty fines and reputational damage.
10. Begin Recovery Planning
Start planning restoration within the first 24 hours, even if full recovery takes longer:
- Identify critical systems for prioritized recovery.
- Use clean, verified backups free of malicious code.
- Restore data to isolated environments first.
- Rebuild with enhanced security measures like updated firewalls, patched vulnerabilities, and stronger encryption.
Thorough validation ensures no lingering threats remain.
Conclusion
The first 24 hours after a cyberattack are make-or-break for minimizing damage from cybercrime, ransomware, DDoS, espionage, or data theft by hackers and cyber criminals.
Organizations with mature incident response plans, regular security awareness training, and robust defenses recover faster and suffer less impact. Cyber threats are inevitable in today’s cyberspace—preparation turns a potential catastrophe into a manageable security incident.
Don’t wait for your systems to be hacked or breached. Review and test your incident response plan today to protect your sensitive information, customers, and business.
