Based on the NIST Special Publication 800-61 incident response life cycle, this playbook outlines the main phases—Preparation, Detection & Analysis, Containment, Eradication & Recovery, and Post-Incident Activity—for handling incidents related to suspicious or malicious domains that imitate an organization’s legitimate domain. These domains are often used for phishing campaigns or other malicious activities.

1. Preparation

During this phase, organizations establish the policies, processes, and tools needed to anticipate, detect, and respond to brand impersonation or domain spoofing incidents.

How Lumu Helps

• Lumu Discover provides continuous monitoring of newly registered domains and automatically flags suspicious or lookalike domains that closely resemble your primary domain(s).
• Configurable alerts allow your security team to respond quickly to any newly discovered domains that could pose a threat.

Recommended Actions

• Leverage Your Domain Monitoring Service
  • Make sure that all your TLDs (Top-Level Domains) are properly registered in Lumu Discovery so that Lumu can properly detect URLs that closely resemble your organization’s legitimate domains.
  • Set up immediate alerting to relevant stakeholders (Security Operations Center, legal team, etc.).
• Define Ownership and Roles
  • Determine which roles and responsibilities are required to handle similar domain situations. Bear in mind that roles and functions may vary depending on your team’s structure and size; however, main functions you may want to take as reference would be:
    • Investigation of suspicious findings
    • Making decisions on takedown requests
    • Legal escalations handling
  • Assign these roles and responsibilities clearly within your team to specific members.
• Maintain an Updated Asset Inventory
  • Create a registry of all your official domains, subdomains, and brand names. This will facilitate monitoring and investigation of potential impersonation incidents. Keeping this registry up to date is of vital importance.
• Security Awareness Training
  • Conduct regular training for your workforce on social engineering, identifying suspicious links and sender addresses, and other relevant adversary techniques. This helps mitigate the risk of employees inadvertently entering sensitive data into malicious sites impersonating the company or sharing sensitive information with attackers creating phishing sites.
• Implement Email Security Controls
  • Use and maintain email validation protocols and standards such as DMARC, DKIM, and SPF for communication within your organization.
  • Configure advanced threat protection tools to filter out potentially spoofed or malicious emails.
  • You can also use Lumu Email Intelligence and any data collection integrations based on email providers to obtain additional compromise intelligence and IoCs.
• Legal and Takedown Preparedness
  • Create and implement organized processes for filing abuse complaints or takedown requests through domain registrars and/or hosting providers. Involve and inform your team of the processes. This goes in line with the assignment of roles and responsibilities.
  • Ensure that you and your team are informed about legal procedures to promptly involve legal counsel in potential brand infringement cases.

2. Detection & Analysis

This phase focuses on identifying suspicious domains, validating them as malicious (or benign), and determining the scope or potential impact of the threat.

How Lumu Helps

• Automated Domain Detection: Lumu continuously scans domain registrars and brand-related data feeds for new or altered domains that could be spoofing your brand.
• Email Intelligence Integrations: Lumu features integrations with email services to collect email metadata and intelligence which can help you detect phishing campaigns targeting employees, a potential sign of impersonation.
• Lumu Email Intelligence: This feature of Lumu connects directly with your email provider to look for potential phishing and malicious emails using metadata from your organization’s inboxes. This can help you detect potential impersonation campaigns.
• Threat Intelligence Integration: Lumu is integrated with an array of open-source intelligence (OSINT) feeds and external tools like VirusTotal or PhishTank which allows to validate immediately whether a hash, IP or URL is malicious. This is helpful when classifying suspicious domains more accurately.

Recommended Actions

• Investigate Alerts from Your Service
  • When a domain closely resembling your own is detected by Lumu Discover, start gathering any available contextual data (e.g., WHOIS information, hosting details, SSL certificates) to address the situation appropriately.
  • Make use of any threat intelligence feeds and validate whether the domain is already marked as malicious.
• Analyze Domain Behavior
  • Examine DNS records (A, MX, TXT, etc.) to see if the domain is actively used for email.
  • If possible, visit the domain using a controlled/sandboxed environment completely isolated from your network to validate whether it hosts phishing pages and/or malware.
• Cross-Check Internal Logs
  • Check email gateway or firewall logs and validate whether there has been any traffic to or from any of the suspicious domains detected by Lumu Discovery.
  • Identify potential employee or customer interactions with the domain. If the domain is recognized as malicious by Lumu, you will be able to find it in the Lumu Portal as a contact on the Incidents view.
• Classify Severity
  • Confirm whether the domain is actually malicious (phishing, hosting malware, etc.), or simply parked/inactive. You can start by validating the domain using the WHOIS protocol and sites like scamadviser, and of course, Lumu’s threat intelligence.
  • After validating, prioritize high-risk domains (those impersonating login portals, payment pages, etc.) for prevention, operation and takedown procedures.
• Engage Threat Intelligence Services
  • If the domain is suspected of phishing or malicious intent, run further analysis (e.g., sandbox analysis for associated files, deeper WHOIS footprint).
  • Correlate with existing threat databases using Lumu to see if the domain is part of a larger campaign.

3. Containment, Eradication & Recovery

Once a domain is identified as malicious, the primary goal is to protect your environment, employees, and customers, and to neutralize or remove the threat.

How Lumu Helps

• Lumu provides centralized takedown facilitation or automated processes to notify registrars/hosts of fraudulent domains.
• Lumu’s Response Integrations allows it to feed IoCs directly into other cybersecurity solutions in your stack such as firewalls so connections to these IoCs can be automatically blocked and terminated.

Recommended Actions

• Block Access and Communication
  • Immediately block the malicious domain (and associated IP addresses) across your network security systems. You can do this manually by extracting IoCs from the Lumu Portal and entering them into your cybersecurity stack to block connections preemptively; however, it is also possible to automate this process through Lumu’s OOTB Integrations.
  • Enforce blocking policies with malicious infrastructure within your SIEM, proxy, and/or secure email gateways.
• Notify and Protect Stakeholders
  • Set up an internal communication strategy to inform employees that a malicious domain is impersonating your organization and prevent them from entering sensitive data into malicious sites.
  • Customers and external users may also be targeted by the impersonation campaign. Prepare an external communication strategy to alert them and help prevent data theft and its associated risks.
• Initiate Takedown Procedures
  • If possible, directly contact the domain registrar or hosting provider to file an abuse complaint, following the plan you should have previously defined.
  • Escalate to legal channels if the domain clearly violates trademarks or engages in fraudulent activity.
• Credential Reset and Security Reviews
  • If you find evidence of credential harvesting, enforce password resets for all potentially affected accounts. Consider restricting their access to critical assets or temporarily disabling them until the incident is under control.
  • Enforce multi-factor authentication (MFA) to collaborator and customer accounts where possible.
• Incident Documentation
  • Keep detailed records of the containment steps, including timelines, actions taken, and involved parties.
  • Archive related logs for potential investigations or legal proceedings.

4. Post-Incident Activity

This phase ensures lessons are learned, defenses are strengthened, and processes are refined to handle future impersonation attempts effectively.

How Your Service Helps

• Lumu’s continuous monitoring ensures that any other similar domain variations are detected opportunely. After taking down a fraudulent site, keep an eye on the Similar Domains section to validate the status of the site, and to learn whether any other fraudulent variations show up.
• Lumu Discover’s EASA reports can assist with root cause analysis and highlight areas for improvement. Use them to find out which improvements can be made to strengthen vulnerable assets, which collaborators need retraining, and how you can improve the general cybersecurity posture of your organization.

Recommended Actions

• Verify Takedown and Blocking
  • Make sure that the malicious domain has been disabled or is no longer accessible. Lumu Discover’s Similar Domains sections is your best ally in this effort.
  • Maintain any blocks implemented to prevent communication with identified malicious infrastructure within your organization. Additionally, uphold any claims and takedown requests to ensure the domain cannot be reused or reactivated..
• Conduct Root Cause Analysis
  • Using all the information provided by the Lumu Portal and your forensic investigation, assess how the incident was discovered, how your organization became aware of it (alert from your monitoring service, customer report, etc.), and how your organization’s lack of preparation may have facilitated its occurrence.
  • Review your organization’s response to the threat—including escalation, takedown, and communication—to assess adherence to predefined procedures and overall efficiency. This evaluation will help improve future responses.
• Policy and Procedure Enhancements
  • Using the information you gained from the review of your organization’s response procedures, conduct any necessary improvements to your response playbooks and propagate the updates among your workforce.
  • Adjust detection thresholds within your service if necessary (e.g., further refining domain similarity matching).
• Training and Awareness
  • Provide training refreshers to your workforce to remind them of the importance of cybersecurity prevention and awareness. Retrain any employees that require thorough instruction based on your forensic investigation of the incident, especially those who handle sensitive customer data. It is vital to reinforce the importance of reporting suspicious domains or emails immediately.
• Ongoing Monitoring
  • Continue carrying out proactive monitoring of the Similar Domains view to track any other potential malicious domains. Make sure that all your main domains are properly registered with Lumu to ensure accuracy.
  • Consider registering high-risk domain variations (common misspellings, brand variations) preemptively to reduce the attacker’s options.
• Documentation and Reporting
  • Compile a comprehensive incident report detailing the timeline of the incident, actions taken by your team, lessons learned, and recommended improvements.
  • Share the resulting report with senior management and any relevant stakeholders. Remember that Lumu Discover can produce EASA reports that can serve as valuable input. Emphasize the role and importance of the tools and technologies that were of use during the incident.