CSIRT War Stories: the underestimated value of false positives
Author:
Scott Walker
CSIRT Manager
Introduction
In the realm of cybersecurity, false positives can often be viewed as mere nuisances. However, a recent incident involving a cloud-based secure remote-control system highlights their potential to trigger significant responses and lessons learned. This blog delves into a CSIRT war story that underscores the importance of understanding false positives and the value of intelligence in incident response.
The incident
Unique control system files
The story begins in an industrial environment where a cloud-based secure remote-control system generates unique client installation files containing Public Key Infrastructure (PKI) cryptographic keys. Each file is distinct, which plays a crucial role in the unfolding of events.
Triggering suspicion
The incident was set in motion when a member of the IT team generated one of these unique files and shared it via MS Teams. Within minutes, an unknown device executed the file and registered itself with the control system, raising immediate alarms.
The phantom user
Upon investigation, the IT team remotely connected to the unknown device, discovering it was running a command prompt that appeared to be attempting to decrypt the unique client file. An inquiry was made to the user of the system, but the session abruptly closed, and the device vanished.
Engaging CSIRT
Given the unique nature of the file, the IT team suspected it had been exfiltrated, prompting the engagement of the CSIRT for a thorough investigation.
The revelation
After the investigation, it was revealed that the incident was a known, albeit rare, false positive. The vendor confirmed that the behavior observed was not malicious but rather a result of Microsoft Defender's scanning process, which had uploaded the file to a sandbox for examination.
Lessons learned
- Value of transparency: This incident illustrates the importance of transparency in security processes. Understanding the nuances of how systems interact can prevent unnecessary panic.
- Incident response preparedness: The incident response processes in place were crucial. Had this not been a false positive, the measures would have mitigated potential data leaks.
- Intelligence utilization: The incident emphasizes the need for intelligence in security operations. By learning from false positives, teams can enhance their response strategies for future incidents.
The importance of incident response retainers
In today's fast-paced digital landscape, incidents can occur at any time. Having a reliable incident response retainer ensures that organizations can respond swiftly to crises, minimizing damage and losses. Key features of a retainer include:
- 24/7 Remote Response Support: Immediate access to professional responders.
- Crisis Management: Experienced specialists to handle incident triage and analysis.
- Advanced Intelligence: Proactive preparation for potential threats.
Conclusion
The CSIRT war story of the false positive incident serves as a reminder of the complexities within cybersecurity. It highlights the need for robust incident response processes, the value of intelligence, and the importance of being prepared for the unexpected. By learning from such experiences, organizations can enhance their security posture and respond more effectively to future threats.