A regular expression (regex) is a sequence of characters that defines a search pattern for text. A regex can be used to extract custom properties from log messages or events in a SIEM platform. In this case, the regex that matches the phrase "File: Clean" exactly is ^File: Clean$. The ^ symbol indicates the beginning of the line and the $ symbol indicates the end of the line. The regex ensures that no other characters are before or after the phrase. References:
* Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS) - Cisco, Module 5: Security Policies and Procedures, Lesson 5.3: Data and Event Analysis
* 200-201 CBROPS - Cisco, Exam Topics, 5.0 Security Policies and Procedures, 5.3 Analyze data as part of security monitoring activities
* Cisco Certified CyberOps Associate Overview - Cisco Learning Network, Videos, 5.3 Analyze data as part of security monitoring activities

When a company workstation is compromised, the stakeholders that must be involved are the ones who are responsible for the security incident response process. According to the table, these are Employee 4 (Security Operation Center Analyst), Employee 6 (Head of Network and Security Infrastructure Services), and Employee 7 (Technical Director). The other employees have different roles that are not directly related to the incident response process, such as accounting, financial management, or system administration. References := Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS) v1.0, Module 1: Security Concepts, Lesson 1.4: Security Monitoring, Topic 1.4.1: Security Operations Center

Threat hunting is a proactive cybersecurity technique that involves searching for indicators of compromise or signs of intrusion within an organization's network or systems. Unlike automated detection systems, threat hunting is typically carried out by security analysts who use their knowledge and intuition to identify subtle, unusual patterns that may indicate a security breach. The goal of threat hunting is to identify and mitigate threats before they can cause significant damage.

Patch management is the process of distributing and managing updates to software and systems. These updates can include patches for security vulnerabilities, bug fixes, and enhancements to improve performance or add new features. It ensures that systems are up-to-date, secure, and performing optimally. References :
= Cisco Cybersecurity Training