Incident severity levels explained

Cyber incident severity levels refer to the degree of severity of a cybersecurity incident, based on the potential impact on an organization. Defining severity levels helps organizations to prioritize incident response efforts, allocate resources, and establish a consistent approach to managing cybersecurity incidents.

The following are the four most commonly used cyber incident severity levels

  • Level 1: Low Severity Incident
  • Level 2: Medium Severity Incident
  • Level 3: High Severity Incident
  • Level 4: Critical Severity Incident

Level 1: Low Severity Incident

These incidents have a minimal impact on the organization and are often isolated incidents that can be quickly resolved by first-level support staff. Examples of Level 1 incidents include minor phishing attacks or spam emails.

Level 1 incidents are considered low severity incidents and typically have a minimal impact on the organization’s operations.

These incidents can be quickly resolved by first-level support staff, and they may not require significant resources or specialized expertise to manage.

Some examples of Level 1 incidents include:

  1. Spam emails: Low severity incidents can include receiving unsolicited emails or spam emails that are not harmful but can be annoying.
  2. Minor network issues: These may include temporary network connectivity issues or slow network speeds, which may impact some users but do not cause significant disruption to the organization’s operations.
  3. Routine malware infections: Some malware infections can be easily detected and removed using antivirus software, and they may not cause significant damage or disruption to the organization’s systems or data.
  4. Minor policy violations: Low severity incidents may also include minor policy violations, such as using personal email or social media during work hours.
  5. Low-level phishing attacks: Low-level phishing attacks may attempt to trick employees into revealing their login credentials or personal information, but they may not be sophisticated enough to cause significant damage or compromise sensitive data.

While Level 1 incidents may not be significant, it is still essential to document and respond to them promptly. This helps to establish a culture of security within the organization and creates a foundation for more robust incident response practices in the future.

Level 2: Medium Severity Incident

Level 2 security incidents have a more significant impact on the organization and require more resources and expertise to resolve. Examples of Level 2 incidents include malware infections affecting a specific department or location or a successful phishing attack that has resulted in the compromise of sensitive data.

Level 2: Medium Severity Incidents have a significant impact on an organization and require more resources and expertise to resolve than Level 1 incidents.

Some examples of Level 2 incidents include:

  1. Malware Infections: Malware infections can compromise the security of an organization’s systems and data. A Level 2 incident might involve malware infections on several systems within a department or location, impacting business operations and requiring more extensive investigation and remediation efforts.
  2. Phishing Attacks: Phishing attacks are social engineering attacks that target employees with the aim of stealing sensitive information or compromising systems. A Level 2 incident might involve a successful phishing attack that has resulted in the compromise of sensitive data or unauthorized access to systems.
  3. Unauthorized Access: Unauthorized access incidents involve unauthorized access to systems or data by employees or external parties. A Level 2 incident might involve unauthorized access to sensitive data, systems, or applications, which can have significant consequences for an organization’s operations and reputation.
  4. Denial of Service (DoS) Attacks: DoS attacks are attacks that overload a system or network with traffic, rendering it unavailable to legitimate users. A Level 2 incident might involve a DoS attack that affects a specific department or location, resulting in a partial or complete loss of services.
  5. Insider Threats: Insider threats are incidents where employees or contractors intentionally or unintentionally compromise the security of an organization’s systems or data. A Level 2 incident might involve an insider threat that has resulted in the unauthorized access or disclosure of sensitive data or system disruption.

Level 3: High Severity Incident

These incidents have a severe impact on the organization and require an immediate response from senior management and specialized incident response teams. Examples of Level 3 incidents include significant data breaches or large-scale malware outbreaks affecting multiple departments or locations.

Level 4: Critical Severity Incident

These incidents have a catastrophic impact on the organization and pose a significant threat to the organization’s reputation, financial stability, or public safety. Examples of Level 4 incidents include ransomware attacks, critical infrastructure disruptions, or data breaches affecting large volumes of sensitive information.

The severity level of a cybersecurity incident is determined by several factors, including the potential impact on the organization, the scope and scale of the incident, the nature of the assets affected, and the potential legal or regulatory consequences.

It is essential to establish a clear and consistent approach to defining and communicating cybersecurity incident severity levels to ensure that the appropriate resources and response protocols are activated to mitigate the impact of the incident.

Organizations must continually review and update their severity level definitions to reflect changes in their threat landscape and operational environment.

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