Indicators of attack (IoAs) are signs that an attack may be in progress or imminent. Malware reinfection within a few minutes of removal (D) is a strong IoA because it suggests that the attacker has a persistent mechanism to redeploy malware, indicating an active compromise of the system.

In the incident response process, detection and analysis involve researching an attacking host through logs in a Security Information and Event Management (SIEM) system. This step helps in identifying, validating, and managing potential security incidents. References := Cisco CyberOps Associate - Module 3: Security Monitoring

The packet capture exhibit shows that the source IP address is 192.168.122.100 and it is sending a packet from source port 50272 to destination port 80 of destination IP address 81.179.179.69 using TCP protocol.
The TCP protocol is indicated by the Protocol field which has the value 6. The source and destination ports are indicated by the SrcPort and DstPort fields respectively. The source and destination IP addresses are indicated by the SrcAddr and DstAddr fields respectively. References := Cisco Cybersecurity Operations Fundamentals - Module 3: Network Data and Event Analysis

Social engineering is a type of testing method that involves manipulating or deceiving people into performing actions or divulging information that can compromise the security of the organization. Social engineering can take various forms, such as phishing, vishing, baiting, quid pro quo, or impersonation. The scenario in the question is an example of a phishing attack, where the intruder sent an email to the user that appeared to be legitimate and contained a malicious link that infected the user's machine and allowed the intruder to access the corporate network. References: [Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS)
- Module 6: Security Incident Investigations]

Deep packet inspection (DPI) analyzes the data part (and possibly also the header) of a packet as it passes an inspection point, searching for protocol non-compliance, viruses, spam, intrusions, or defined criteria to decide whether the packet may pass or if it needs to be routed to a different destination. Stateful inspection, on the other hand, tracks the state of active connections and determines which network packets to allow through the firewall. While stateful inspection tracks the state of connections (Layer 4 - transport layer), DPI goes further by examining the payload of the packet (Layer 7 - application layer).