Investigating all symptoms to confirm the incident is the first step in the incident response process. An incident is an event that violates or threatens the security, availability, integrity, or confidentiality of the IT systems or data. An incident response is a process that involves detecting, analyzing, containing, eradicating, recovering, and learning from an incident, using various methods and tools. An incident response can provide several benefits, such as:

Improving the security and risk management of the IT systems and data by identifying and addressing the security weaknesses and gaps

Enhancing the security and decision making of the IT systems and data by providing the evidence and information for the security analysis, evaluation, and reporting

Increasing the security and improvement of the IT systems and data by providing the feedback and input for the security response, remediation, and optimization

Facilitating the compliance and alignment of the IT systems and data with the internal or external requirements and standards

Investigating all symptoms to confirm the incident is the first step in the incident response process, because it can ensure that the incident is verified and validated, and that the incident response is initiated and escalated. A symptom is a sign or an indication that an incident may have occurred or is occurring, such as an alert, a log, or a report. Investigating all symptoms to confirm the incident involves collecting and analyzing the relevant data and information from various sources, such as the IT systems, the network, the users, or the external parties, and determining whether an incident has actually happened or is happening, and how serious or urgent it is. Investigating all symptoms to confirm the incident can also help to:

Prevent the false positives or negatives that might cause the incident response to be delayed or unnecessary

Identify the scope and impact of the incident on the IT systems and data

Notify and inform the appropriate stakeholders and authorities about the incident

Activate and coordinate the incident response team and resources

The other options are not the first steps in the incident response process, but rather steps that should be done after or along with investigating all symptoms to confirm the incident. Determining the cause of the incident is a step that should be done after investigating all symptoms to confirm the incident, because it can ensure that the root cause and source of the incident are identified and analyzed, and that the incident response is directed and focused. Determining the cause of the incident involves examining and testing the affected IT systems and data, and tracing and tracking the origin and path of the incident, using various techniques and tools, such as forensics, malware analysis, or reverse engineering. Determining the cause of the incident can also help to:

Understand the nature and behavior of the incident and the attacker

Detect and resolve any issues or risks caused by the incident

Prevent and mitigate any future incidents or attacks involving the same or similar cause

Support and enable the legal or regulatory actions or investigations against the incident or the attacker

Disconnecting the system involved from the network is a step that should be done along with investigating all symptoms to confirm the incident, because it can ensure that the system is isolated and protected from any external or internal influences or interferences, and that the incident response is conducted in a safe and controlled environment. Disconnecting the system involved from the network can also help to:

Prevent the incident from communicating or connecting with any other system or network, and potentially spreading or escalating the attack

Prevent the incident from receiving or sending any commands or data, and potentially altering or deleting the evidence

Prevent the incident from detecting or evading the incident response, and potentially hiding or destroying itself

Isolating and containing the system involved is a step that should be done after investigating all symptoms to confirm the incident, because it can ensure that the incident is confined and restricted, and that the incident response is continued and maintained. Isolating and containing the system involved involves applying and enforcing the appropriate security measures and controls to limit or stop the activity and impact of the incident on the IT systems and data, such as firewall rules, access policies, or encryption keys. Isolating and containing the system involved can also help to:

Minimize the damage and loss caused by the incident on the IT systems and data

Maximize the recovery and restoration of the IT systems and data

Support and enable the eradication and removal of the incident from the IT systems and data

Facilitate the learning and improvement of the IT systems and data from the incident