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Incident handling (IH) is a structured process for detecting, responding to, and recovering from cybersecurity incidents. It's a key defensive capability for organizations that must protect the confidentiality, integrity, and availability of their systems.
To better understand what incident handling involves, it’s important to clarify some terminology. In computing, an event is any observable occurrence within a system or network—such as a user sending an email, clicking a mouse, or a firewall allowing a connection. Not all events are harmful; however, when an event results in a negative outcome, such as a system crash or unauthorized access to sensitive data, it becomes an incident.
More specifically, an IT security incident refers to any event with a deliberate intent to cause harm to an information system. This includes activities like data breaches, theft of funds, the unauthorized use of malware or remote access tools, and the compromise of confidential information. It's worth noting that incidents are not limited to cyberattacks—they may also involve internal threats, availability disruptions, or even natural disasters that affect digital infrastructure. A solid incident handling strategy should be able to identify, contain, eradicate, and recover from such incidents, aiming to restore normal operations as efficiently as possible. Sometimes, it might not be immediately evident whether an event qualifies as an incident until a preliminary investigation is conducted. That’s why it’s often safer to treat suspicious events as potential incidents until they’re ruled out.
Incident handling is not limited to external intrusions. It also includes threats from insiders, service availability issues, and loss of intellectual property. The goal is to detect, contain, eradicate, and recover from incidents efficiently.Sometimes, an event may not clearly be an incident until it is investigated. Suspicious events should be treated as incidents unless proven otherwise.
Incident handling teams provide a systematic response to reduce impact. Their objectives include minimizing data theft and service disruption. This is done through investigation and remediation.Different incidents require different levels of response. Prioritization is essential: critical incidents need immediate attention, while others may require only initial investigation.
The incident manager (often a SOC manager, CISO, or trusted third party) leads the response, coordinates teams, and tracks actions taken. They must have the authority to involve any business unit as needed.
Before diving into incident handling, it's crucial to understand the concept of the attack lifecycle—commonly referred to as the Cyber Kill Chain. This model outlines the different stages of a cyberattack and helps us assess how far an adversary may have progressed in our network during an incident. By understanding these stages, we can better prioritize our response and mitigation efforts.
Gathering information about the target through public or active means to prepare the attack.
Crafting malware or exploit payloads based on the recon data to ensure successful compromise.
Transmitting the malicious payload to the victim via email, web, USB, or other vectors.
Triggering the exploit or executing the payload to gain access to the target system.
Installing malware on the compromised system to establish persistent access.
Establishing a communication channel with the compromised system to issue commands and retrieve data.
Achieving the attacker’s goals, such as data exfiltration, privilege escalation, or ransomware deployment.
The chain begins with reconnaissance, where an attacker selects a target and begins gathering information. This can be done passively, using publicly available data from platforms like corporate websites, or job listings, which may reveal details about software, infrastructure, even security tools used by the organization. In some cases, attackers take it further by actively scanning exposed web applications or public IP addresses to identify vulnerabilities.
Once sufficient information is collected, the attacker moves to the weaponization stage. Here, custom malware or exploit payloads are crafted to ensure undetected and reliable access to the target environment. These are often designed to bypass antivirus and endpoint detection systems, relying on intelligence gathered during reconnaissance to ensure compatibility and stealth.
In the delivery phase, the payload is transmitted to the victim—commonly via phishing emails with malicious attachments or links to spoofed websites. Attackers may impersonate trusted sources or even use phone calls as part of their social engineering strategy. In more targeted cases, they may deploy USB devices containing malicious files to gain initial access.
The exploitation phase is where the attack begins to execute. At this point, the delivered payload is activated, typically leveraging a software vulnerability or user action to run malicious code on the system. If successful, this marks the transition from access attempt to actual compromise.
Following this is the installation phase, during which the attacker deploys their malware onto the system. Techniques include droppers that install secondary tools, backdoors for persistent access, and rootkits that help hide the presence of malicious components. These elements often allow for long-term control of the target machine and pave the way for deeper network penetration.
In the command and control (C2) stage, the attacker establishes communication between the compromised host and their own infrastructure. This allows them to issue commands, upload new tools, or extract data. More sophisticated attackers use redundant C2 channels or modular stagers that can adapt in real time, ensuring they maintain access even if some parts of their operation are discovered.
The final phase is the action on objectives. Depending on the attacker’s goals, this could involve stealing sensitive data, encrypting systems with ransomware, escalating privileges, or disrupting services. Every action taken at this point directly contributes to the attack’s intended outcome.
It's important to understand that this lifecycle is not strictly linear. Attackers may loop back to earlier stages—like performing further reconnaissance after initial access—to expand their reach or solidify control. Our goal as defenders is to disrupt this cycle as early as possible, ideally during the recon or delivery phase, before significant damage is done.
Now that we understand how attacks unfold through the cyber kill chain, it's equally important to know how to respond effectively when an incident occurs. The Incident Handling Process, as defined by NIST, provides a structured and repeatable approach to managing security incidents—from early preparation to post-incident analysis. This process helps organizations reduce impact, recover quickly, and strengthen their overall security posture.
This stage focuses on establishing and maintaining an incident response capability. It involves developing policies, procedures, training plans, communication strategies, and setting up detection and forensic tools to prepare for future incidents.
Here we identify and confirm whether an incident has occurred. Activities include monitoring systems, analyzing logs, correlating alerts, and assessing impact. This is often the most time-consuming phase and requires skilled analysis and documentation.
Once confirmed, the incident must be contained to limit damage, then eradicated by removing the threat, and finally recovered by restoring systems and returning to normal operations. All infected elements must be addressed to avoid reinfection or tipping off the adversary.
After the incident, a report is prepared with a full timeline, root cause, affected systems, and lessons learned. This stage helps improve defenses, update documentation, and enhance future response capability through review and refinement.
In the preparation stage, the organization focuses on two main goals: establishing an incident handling capability and putting in place proactive defenses to prevent security incidents. While prevention is not solely the responsibility of the incident response team, it is essential for the team's success. Measures like endpoint hardening, multi-factor authentication, privileged access management, and Active Directory tiering all play a role.
To ensure readiness, the organization must have a skilled and trained incident response team, comprehensive security awareness across the workforce, clear policies and documentation, and the appropriate software and hardware tools.
Written documentation should include updated contact lists (e.g., legal, IT, law enforcement, ISPs), incident response policies and procedures, system/network baselines, asset inventories, and privileged accounts that can be enabled when needed. These documents help guide the response process and ensure coordination across departments.
Quick access to resources is crucial—such as the ability to acquire tools without going through full procurement approval. Legal implications must also be considered, especially in scenarios like data breaches, where regulatory compliance (e.g., GDPR) mandates reporting.
As incidents unfold, it’s critical to document everything: timestamps, actions taken, who performed them, and the outcomes. These records can later help reconstruct timelines and determine lessons learned.
Proper tooling is another pillar of preparation. This includes forensic laptops, memory and disk capture tools, network analysis devices, log parsers, and jump bags containing everything needed to investigate and respond quickly. Tools like screwdrivers, hard drives, write blockers, and power cables might sound basic—but they are vital when working on physical systems under time pressure.
Lastly, your documentation and communications infrastructure must be independent from the organization’s core systems. Always assume the worst: that internal systems are compromised. Keep sensitive notes and communications away from email and shared drives within the affected domain.
Another crucial aspect of preparation is understanding and aligning with the protective measures implemented across the organization. While these defenses are not always managed by the incident response team, knowing how they work allows the team to recognize how an attack was mitigated or bypassed, and where forensic artifacts may reside.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an anti-phishing email protection protocol built on top of SPF and DKIM. It prevents attackers from spoofing an organization’s domain in phishing attempts. Proper testing before deployment is critical to avoid accidentally blocking legitimate emails. Additionally, some systems allow rules to act on DMARC failures even for non-owned domains, although this too must be implemented with caution due to potential false positives.
Endpoints are a common attack vector. Applying hardening baselines like those from CIS or Microsoft is essential. Practical steps include disabling LLMNR/NetBIOS, removing unnecessary admin privileges, constraining PowerShell, enabling ASR rules, and deploying application whitelisting (at least blocking execution in writable directories). Host-based firewalls should limit lateral movement and restrict outbound traffic to known LOLBins. Deploying a robust EDR that integrates with AMSI (for script visibility) adds a strong layer of defense.
Segmentation prevents an attacker from moving laterally across the network. Internal services should not be directly exposed to the internet unless properly isolated in a DMZ. IDS/IPS systems become far more effective when combined with SSL/TLS interception, enabling detection of malicious content beyond simple IP reputation. Restricting network access to trusted, organization-managed devices (via 802.1x or Conditional Access in Azure environments) is also key to defending against rogue connections.
Credential theft is a leading cause of escalation. Many admin users rely on weak or reused passwords. Encourage passphrases—long, memorable, and hard to brute-force—such as "i LIK3 my coffeE warm". Promote the use of different passwords for admin and personal accounts. Multi-factor authentication (MFA) must be enforced for all privileged access across systems and applications to mitigate credential-based attacks.
Besides endpoint and network protection, there are several complementary actions that can significantly improve an organization’s readiness to face cyber threats. These measures provide both technical and human layers of defense, and can also enhance overall visibility and response maturity.
Perform regular and automated vulnerability scans across your entire environment. Focus on identifying and remediating vulnerabilities rated as high or critical. Although detection can be automated, remediation often requires manual action. If patching is not possible in the short term, isolate affected systems through proper network segmentation to reduce exposure.
Human error is still a leading cause of incidents. Deliver ongoing training to help employees recognize suspicious behavior and report potential threats. This training should be reinforced through periodic unannounced testing, such as simulated phishing campaigns or purposely dropped USB drives in common areas, to assess awareness levels and response behavior in real situations.
Active Directory (AD) is often a target for escalation once an attacker compromises an endpoint. Conducting regular security assessments of your AD environment will help reveal misconfigurations or known escalation paths before an adversary can exploit them. If the organization lacks in-house expertise, consider involving a trusted third party. These assessments are especially valuable because AD vulnerabilities evolve constantly and many administrators are unaware of recently published issues.
Purple teaming combines the strengths of red (offensive) and blue (defensive) teams in a collaborative simulation. The red team performs real-world attack techniques, while the blue team monitors, detects, and responds in real-time. Unlike adversarial exercises, the red team shares findings and blind spots, allowing the defenders to improve visibility, validate detection logic, and test incident handling playbooks. These exercises are invaluable for building effective, well-trained response teams.
Once an incident handling capability is in place, we must focus on the detection and analysis phase. This stage involves identifying potential threats through sensors, logs, alerts, and human observation. Threat intelligence and visibility across the network are key components to performing effective detection and understanding what’s happening in real-time. Threats can be introduced through numerous attack vectors and might be detected via:
To increase visibility, detection efforts should be deployed across different layers of the environment:
Once a potential incident is detected, we need to assess the situation before initiating a full-scale organizational response. This includes gathering contextual information such as the detection source, timing, type of incident, and impacted systems. Misinterpreting a detail like timezone or IP ownership can lead to wrong conclusions, so collecting detailed and accurate information is essential.
During this stage, try to answer questions such as:
As you collect data, you should begin building a timeline of the incident. This timeline helps visualize the sequence of attacker actions and understand how the compromise evolved. Each entry should include the date, time, hostname, description, and data source. For example:
| Date | Time | Hostname | Event Description | Data Source |
|---|---|---|---|---|
| 09 / 09 / 2021 | 13:31 CET | SQL Server01 | Hacker tool 'Mimikatz' was detected | Antivirus Software |
Based on initial findings, ask the following questions to estimate the severity and spread of the incident:
Incident data is highly sensitive. Information should only be shared on a strict need-to-know basis. Communication—especially with third parties—should be coordinated by the designated contact person in consultation with legal advisors. During the investigation, document expectations, available evidence, time estimates, and the feasibility of identifying the attacker. Update stakeholders regularly with new developments and any change in scope.
Investigations begin using the initial data gathered when the incident was first detected. From there, the incident handling team follows a cyclic process of:
The initial leads form the basis of the investigation. It's crucial not to fixate on a single tool or artifact. Broadening the scope often uncovers more relevant findings and gives a more complete understanding of the compromise.
IOCs (Indicators of Compromise) are artifacts such as IP addresses, file hashes, or filenames that indicate malicious activity. These are documented using formats like OpenIOC or YARA. Using proper tooling (e.g., IOC editors or automation scripts via PowerShell or WMI), IOCs can be deployed across an environment to identify additional compromised systems.
Caution must be exercised when accessing potentially compromised systems to avoid caching privileged
credentials. Tools like PsExec behave differently depending on usage and may leave traces. Use
secure protocols like WinRM with non-caching login types where possible.
IOC scans may reveal a large number of hits. Not all will be relevant, so eliminating false positives and prioritizing based on forensic potential is key. This ensures that the investigation stays focused on systems that can generate new insights.
Once new systems are identified, data must be preserved for analysis. This can be done via live response or full system imaging. Live response is more common, but it’s critical to minimize changes on the system to maintain evidence integrity. Shutting down a system may result in losing volatile data, especially from memory.
Collected data is then analyzed using malware analysis, disk forensics, and increasingly, memory forensics. The timeline is updated with validated findings as the investigation progresses. Proper chain-of-custody documentation must be maintained for legal admissibility of any evidence.
After the investigation concludes and we understand the nature and impact of the incident, the next step is containment. This stage aims to prevent the incident from spreading further and causing additional harm to the organization.
Containment is split into short-term and long-term efforts. It's essential that containment actions are coordinated across all affected systems simultaneously to avoid alerting the adversary and giving them time to adapt.
Short-term containment includes minimal-impact actions like isolating systems on a separate VLAN, unplugging network cables, or redirecting C2 domains. These measures stop the bleeding while allowing time for evidence preservation and remediation planning. Communication with the business is crucial if system shutdowns are involved.
Long-term containment involves more permanent changes such as password resets, firewall rule updates, HIDS deployment, patch application, or system shutdowns. These actions mark the transition from containing the incident to preparing for full recovery, and regular communication with stakeholders is vital throughout.
Eradication focuses on removing the adversary and all traces of the incident from the environment. This may involve malware removal, system rebuilds, and restoring clean backups. Additional patches and system hardening may be applied not only to affected systems but also across the infrastructure to mitigate future attacks.
Once systems are clean, they are reintroduced into production after careful testing and validation. Continuous monitoring is critical, as systems that were previously compromised may be targeted again. Focus areas include:
Recovery may span weeks or months depending on the scale of the incident. Early recovery phases address immediate risks with quick fixes, while later phases focus on implementing long-term, strategic improvements to strengthen the organization’s security posture.
In the final stage of the incident handling process, the focus shifts to documentation, evaluation, and improvement. This is our chance to reflect on the incident — what happened, how we responded, and how effective our actions were. This phase usually includes a meeting with all stakeholders shortly after the incident is resolved, once the incident report is ready.
A well-structured report is critical. It answers key questions like:
These reports provide measurable insights, such as how many incidents were handled, the average response time, and what was done during each case. They are also useful as references for similar incidents in the future and may serve as legal documentation if required in court.
Post-incident reports are also excellent tools for onboarding new team members, allowing them to learn from real events handled by experienced staff. This is the right time to assess whether plans, policies, and procedures need to be updated. Beyond documentation, we must also reexamine the team's tools, training, readiness, and structure to ensure continual improvement.
We will explore the reporting aspect of the incident handling process in more depth in the Security Incident Reporting module of the SOC Analyst job role path.