infoTECH Feature

January 17, 2023

An Incident Response Process for Zero Day Attacks

Defining Zero-Day Exploits, Vulnerabilities, and Attacks

A zero-day vulnerability is a previously unknown vulnerability in a computer system or application that can be exploited by attackers. These vulnerabilities are called "zero-day" because they are not known to the software vendor or to the security community at large, so there is zero time for the vendor to fix the vulnerability before it is exploited.

A zero-day exploit takes advantage of a zero-day vulnerability. An exploit is a piece of software, code, or technique that takes advantage of a vulnerability in order to gain unauthorized access to a system or perform some other malicious action. A zero-day attack uses a zero-day exploit to target a system or application.

To summarize, a vulnerability is a weakness in a system or application that can be exploited by attackers, an exploit is the tool or technique used to exploit that vulnerability, and an attack is when the attackers actively compromise the target.

Why Are Zero-Day Exploits Dangerous?

Because zero-day attacks are unknown, potential vulnerabilities often go undetected. The payload could be remote code execution, ransomware, credential theft, denial of service (DoS), or other threat vectors. Zero-day vulnerabilities can put organizations at risk for months before they are discovered and contained.

Organizations can become victims of advanced persistent threats (APTs) due to unknown vulnerabilities. APTs are particularly dangerous, because these attackers plan for the long term, leaving backdoors to allow persistent ongoing access to the network. They use sophisticated malware to traverse a network and access sensitive systems.

Another threat vector for zero-day exploits is bring-your-own-device (BYOD) policies. These increase the risk the local network could be penetrated, as users can bring unsecure devices from home to work. If a user's device is compromised, the entire corporate network can become infected.

Yet another way organizations can become exposed to zero days is insider threats. A malicious insider can tip hackers into the presence of a vulnerable system in an organization, or even exploit it themselves, leading to a zero day attack.

The longer a vulnerability is undiscovered, the longer an attacker can exploit it. An unknown zero-day vulnerability could allow attackers to exfiltrate gigabytes of data. Data is often exfiltrated slowly to avoid detection, resulting in millions of records being lost before an organization detects a breach.

How a Zero-Day Attack Works

Every attack is different, but in general zero day attacks follow this process:

  1. Developers release a version of an application or system, which contains zero-day vulnerabilities unknown to the developers.
  2. Once the system is up and running, attackers discover vulnerabilities in the system. Hackers can obtain information about zero-day vulnerabilities on black or gray markets, or through research published by legitimate security experts.
  3. Attackers create and execute malicious code to exploit the vulnerability and compromise the system (a zero day exploit).
  4. The software vendor becomes aware of a problem and fixes the problem with a patch.
  5. Users of the software or system deploy the patch to protect themselves.

Incident Response Process for Zero-Day Vulnerabilities

The incident response process for zero-day vulnerabilities generally involves the following steps:

  1. Identification and confirmation: Identify and confirm that a zero-day vulnerability has been exploited. This may involve analyzing network traffic, examining system logs, and reviewing alerts from security monitoring tools.
  2. Assessment and scope: Once the incident has been confirmed, the next step is to assess the impact and scope of the attack. This may involve determining which systems and assets have been affected, and what data may have been accessed or compromised.
  3. Containment: The goal of containment is to prevent the attacker from gaining further access to the affected systems and assets, and to minimize the damage caused by the attack. This may involve disconnecting affected systems from the network, blocking access to specific IP addresses or domains, and deploying additional security controls such as firewalls or intrusion prevention systems.
  4. Eradication: The next step is to eradicate the cause of the incident, which may involve patching the zero-day vulnerability, removing malicious software or code, and restoring affected systems to their pre-attack state.
  5. Recovery: This may involve restoring systems and data to their pre-attack state, and implementing additional security measures to prevent future attacks.
  6. Post-incident review: Once the incident has been resolved, it is important to conduct a post-incident review to identify any lessons learned and areas for improvement. This may involve analyzing the incident response process, reviewing security controls and protocols, and identifying any additional training or resources that may be needed to prevent future incidents.

It is important to note that the incident response process may vary depending on the specifics of the incident, and may involve additional steps or activities as needed. The goal of the incident response process is to restore normal operations as quickly as possible while minimizing any negative impact on the organization.


In conclusion, zero-day attacks can be particularly dangerous and difficult to defend against due to their exploitation of previously unknown vulnerabilities. It is therefore important for organizations to have a robust incident response plan in place to address such attacks and minimize their impact. The incident response process for zero-day attacks generally involves the identification and confirmation of the attack, assessment and scope, containment, eradication, recovery, and post-incident review.

By following this process, organizations can effectively respond to zero-day attacks and protect themselves against future incidents. It is also important for organizations to keep their software and operating systems up to date, and to implement other security measures such as firewalls, antivirus software, and intrusion prevention systems to protect against zero-day vulnerabilities.


Subscribe to InfoTECH Spotlight eNews

InfoTECH Spotlight eNews delivers the latest news impacting technology in the IT industry each week. Sign up to receive FREE breaking news today!
FREE eNewsletter

infoTECH Whitepapers