System Intrusion Detection and Prevention

Responding to a system intrusion involves several key phases: containment, eradication, recovery, and post-incident analysis. These phases are components of an incident response plan.

Ways of Responding:

• Containment: This involves isolating the compromised system or network segment to prevent the intrusion from spreading further. An example is disconnecting an infected server from the network or reconfiguring firewalls to block malicious traffic.
• Eradication: Removing the cause of the intrusion, which might involve patching vulnerabilities, updating software, removing malware, or changing compromised credentials. For instance, if an attacker exploited a known software flaw, applying the vendor's security patch would be part of eradication.
• Recovery: Restoring affected systems and data to their operational state. This often means restoring from clean backups to ensure data integrity and system functionality.
• Forensic Analysis: Investigate the intrusion to understand its scope, methods, and data accessed. This investigation helps prevent future attacks and supports potential legal action.
• Reporting and Legal Action: Notifying relevant authorities, such as law enforcement, and pursuing legal remedies against the perpetrators, especially for significant breaches.

Best Responses:
The most effective responses combine speed and thoroughness. Following a defined incident response plan is important. This ensures rapid containment, such as isolating a compromised system, followed by forensic analysis. Restoring from verified, clean backups is also a crucial part of maintaining data integrity and business operations.

Most Implementable Responses:
Initial containment actions, like disconnecting a compromised system, are highly implementable. This requires appropriate network segmentation and clear procedures. Restoring from backups is also highly implementable if a robust backup and recovery strategy is part of the organization's disaster recovery plan.

Most Cost-Effective Responses:
Prompt containment measures, such as system shutdown or isolation, are often the most cost-effective in the short term. They limit immediate damage and prevent the intrusion from spreading. Proactive investment in intrusion detection systems (IDS) and prevention systems (IPS) can also be cost-effective. These systems reduce the likelihood and impact of successful intrusions. A well-tested incident response plan and comprehensive backups also reduce the total cost of recovery after an intrusion.