The first course of action that the auditor should recommend after finding that several employees are spending an excessive amount of time using social media sites for personal reasons is to implement policies addressing acceptable usage of social media during working hours. Policies can help define the scope, purpose, rules, and expectations of using social media in the workplace, both for personal and professional reasons. Policies can also specify the consequences of violating the policies, such as disciplinary actions or termination. Policies can help deter employees from misusing social media at work, which could affect their productivity, performance, or security. Policies can also help protect the organization from legal liabilities or reputational damages that could arise from inappropriate or unlawful employee behavior on social media.

An acceptable use policy (AUP) is a preventive control that sets out rules and guidelines for using an organization's IT resources, including networks, devices, and software1. It defines acceptable and prohibited behaviors, aiming to protect assets, ensure security, and maintain a productive work environment1. By agreeing to and documenting an AUP for the equipment, both organizations can prevent potential misuse of IT resources2345.
References:
* ISO 27001 Acceptable Use Policy Beginner's Guide - High Table
* Acceptable Use Policy for Information Technology Resources
* Acceptable Use Policies for Workplace Technology | Verizon
* IT Governance: Your Must-Have Policies - How-To Geek
* Acceptable use policy template - Workable

A stateful firewall provides the greatest assurance that outgoing Internet traffic is controlled, as it monitors and filters packets based on their source, destination and connection state. A stateful firewall can prevent unauthorized or malicious traffic from leaving the network, as well as block incoming traffic that does not match an established connection. An intrusion detection system (IDS) can detect and alert on suspicious or anomalous traffic, but it does not block or control it. A security information and event management (SIEM) system can collect and analyze logs and events from various sources, but it does not directly control traffic. A load balancer can distribute traffic among multiple servers, but it does not filter or monitor it. References:
CISA Review Manual (Digital Version), Chapter 6, Section 6.2

The IS auditor's best course of action if they suspect an organization's computer may have been used to commit a crime is to contact the incident response team to conduct an investigation. The incident response team is a group of experts who are responsible for responding to security incidents, such as data breaches, ransomware attacks, or cybercrimes. The incident response team can help to preserve and collect digital evidence, determine the scope and impact of the incident, contain and eradicate the threat, and restore normal operations. The IS auditor should not examine the computer themselves, as they may inadvertently alter or destroy potential evidence, or compromise the chain of custody. The IS auditor should also not notify local law enforcement before further investigation, as this may escalate the situation unnecessarily or interfere with the internal investigation process. The IS auditor should advise management of the crime after the investigation, or as soon as possible if there is an imminent risk or legal obligation to do so.