The Lumu Data Exfiltration Incident Response Playbook is based on the Computer Security Incident Handling Guide by the National Institute of Standards and Technology (NIST). According to NIST special publication 800-61, the incident response life cycle has four main phases, as described in the following illustration.

Based on the source: NIST special publication 800-61

This document contains guidelines for Data Exfiltration incident response using Lumu. Consider this playbook as a guideline to improve the effectiveness of the incident response and adapt it according to your specific requirements.

What are Data Exfiltration incidents?

Lumu is capable of detecting Data Exfiltration activity targeting your organization's sensitive data. Today, many ransomware groups utilize a double extortion method where they exfiltrate data before encrypting it; if they cannot encrypt the data, they threaten to disclose it to collect payment.

Most modern attack chains utilize Living off the Land (LotL) techniques, which involve using legitimate binaries, drivers, or programs for malicious purposes. A primary example is Rclone, a program designed for backups that is compatible with over 70 different cloud storage providers. Attackers use these legitimate tools and scripts to exfiltrate information to common cloud infrastructures like Mega or Dropbox because these connections often do not raise suspicion in corporate environments.

By identifying Data Exfiltration incidents, Lumu helps your organization gain insight into:

• API-Level anomalies: Lumu detects when communication moves beyond a simple website visit and starts interacting directly with cloud storage APIs for data transfer.
• Outbound traffic peaks: Lumu monitors for high-volume outbound data flows that deviate significantly from your organization’s normal behavior.
• Late-stage attacks: By correlating exfiltration with previous alerts (like Phishing or Malware), Lumu helps identify the final stage of a planned attack.

The data used to identify this type of incident includes:

• Network metadata: Firewall and proxy logs containing packet sizes and full URL paths.
• Transfer context: Identification of large transfers occurring at abnormal times.

In this article, you will find a general playbook to operate Data Exfiltration incidents alongside an example scenario.

General Playbook

This is the general playbook for Data Exfiltration incident operation. It covers the main steps that you can take when investigating and remediating this type of incident.

Example Scenario

Now, let’s delve into a common scenario that an organization can find when operating Data Exfiltration incidents. This will help exemplify the value this feature can provide.

Let’s consider a scenario where Lumu notifies your organization that a specific endpoint is sending a high volume of outbound traffic that deviates from the company's baseline triggering the Data Exfiltration detection. To resolve the incident, the analyst starts to investigate to determine the 2 potential paths for this attack.

Case A: Transfer to an authorized cloud storage provider

1. Organization A gets notified of a Data Exfiltration incident. By inspecting the incident, the analysts in charge will be able to access its details to learn more relevant information about the incident, as well as additional context to better operate it.

2. After analysis of the information of the incident, they notice the data is being transferred to an authorized cloud service; however, Lumu still notified the incident as the amount of data being transferred is highly anomalous for the organization’s standards while also being done at unusual hours for it to be a normal operation which raises the alert.

3. Since it is an authorized cloud service, the analysts cannot directly block the connection via firewall as it will affect the normal operations of the organization.

4. After verifying whether the endpoint has the required permission to perform this type of activity, the analysts contact the owner of the asset to verify if this data transfer was done intentionally or was in fact an attack to the organization.

If the data transfer was intentional, for operations like a sporadic backup, the analysts document the information and close the incident.

5. Having determined that it is in fact a Data Exfiltration incident, the analysts immediately contain the asset involved in the incident to prevent any further data exfiltration.

6. Once the immediate risk has been contained, analysts start investigating the root cause of this incident by correlating the endpoint with previous incidents reported, such as an Unusual Login or a Malware or Phishing incident, as this will indicate the initial stages of the attack.

7. After a thorough analysis of the asset, the security team eliminates the malicious binaries and configuration files that were causing the unauthorized connections. Then, they perform an account compromise verification to discard lateral movement. If any account compromise is identified, an account reset must be executed, and if there is lateral movement, the investigation must continue up to the compromised devices to carry out the same measures.

8. Once analysts have remediated the incident, they document their findings and keep the asset under surveillance for any additional contacts with unauthorized cloud storage APIs or signs of re-infection, ensuring that the threat has been completely eradicated.

9. Lastly, the security team makes an investigation to identify the data that has been exfiltrated to respond accordingly.

Case B: Transfer to an unauthorized cloud storage provider

1. Organization A gets notified of a Data Exfiltration incident. By inspecting the incident, the analysts in charge will be able to access its details to learn more relevant information about the incident, as well as additional context to better operate it.

2. Now the analysts check the cloud to which the data is being sent to verify whether the data transfer is legitimate and notices the cloud is not included within the authorized clouds of the organization.

3. Having determined that this a clear exfiltration of data to an unauthorized cloud, the analysts immediately block the IP to which the data is being sent and start the containment measures with the asset that is being affected to prevent further incidents.

4. Then, the analysts start a thorough investigation to determine the cause of the incident. During their investigation, they notice the asset was involved in a previous incident.

5. Noticing that during the previous incident the machine has been previously infected, the analysts manage to eliminate the malicious binaries and configuration files that were causing the incident. Then, they perform an account compromise verification to discard lateral movement. If any account compromise is identified, an account reset must be executed, and if there is lateral movement, the investigation must continue up to the compromised devices to carry out the same measures.

6. Once analysts have remediated the incident, they document their findings and keep the asset under surveillance for any additional contacts with unauthorized cloud storage APIs or signs of re-infection, ensuring that the threat has been completely eradicated.

7. Lastly, the security team makes an investigation to identify the data that has been exfiltrated to respond accordingly.

Preparation

This is the initial phase where organizations take preventive measures to respond effectively to incidents, some recommended steps to prepare your company to deal with a Data Exfiltration incident are listed below:

• Incident Handler Communications and Facilities: It’s vital to gather contact information of everyone involved with incident response to facilitate contact during an incident. Compilate contact information of incident response (IR) team members, external IR teams, and eventually law enforcement, with primary and backup contacts. Determine the escalation and de-escalation criteria and incident reporting mechanisms, such as phone numbers, email addresses, and secure instant messaging.
• Roles and Responsibilities: Details of the roles and responsibilities of key individuals and teams responsible for incident response and decision-making should also be gathered at this stage.
• Training and awareness: Train the incident response (IR) team to identify common MITRE ATT&CK techniques used by adversaries that involve logging in to corporate accounts to damage the organization, and study possible mitigations:
  • ID T1567 - Exfiltration Over Web Service: Adversaries may use an existing, legitimate external Web service to exfiltrate data rather than their primary command and control channel. Popular Web services acting as an exfiltration mechanism may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to compromise. Firewall rules may also already exist to permit traffic to these services.
  • ID T1537 - Transfer Data to Cloud Account: Adversaries may exfiltrate data by transferring the data, including through sharing/syncing and creating backups of cloud environments, to another cloud account they control on the same service. A defender who is monitoring for large transfers to outside the cloud environment through normal file transfers or over command and control channels may not be watching for data transfers to another account within the same cloud provider.
  • ID T1567.002 - Exfiltration to Cloud Storage: Adversaries may exfiltrate data to a cloud storage service rather than over their primary command and control channel. Cloud storage services allow for the storage, edit, and retrieval of data from a remote cloud storage server over the Internet.

How Lumu Helps

Lumu provides the ability to illuminate the blind spots in your network by providing coverage of your entire infrastructure, namely on-premises, public and private clouds, and roaming devices.

• To gain full visibility into your network, set up collectors such as Virtual Appliances, Gateways, Agents and integrations to ensure that all your network metadata is ingested in the Lumu platform, especially the firewall and proxy metadata. Learn more in our deployment guide.
• Identify and limit the cloud providers used by your organization, follow the Principle of Least Privilege to reduce your organization's attack surface.
• Ensure you cover remote users in your compromise assessment. Learn more about Lumu Agent and VPN and SDP configuration.
• Identify your vital assets (clients, IoT, clouds, remote devices, etc.) and assign labels to your traffic to help quickly identify the compromise distribution across your infrastructure in a way that makes sense for your organization.
• Control your attack surface by ensuring that services and connections exposed to external environments are governed by strict policies and controls. Verify that only essential services are exposed, and access is restricted to specific roles via secure, authenticated channels. Regularly monitor and enforce these measures to minimize vulnerabilities.
• Conduct regular awareness campaigns on security policies and risks employees face, and what actions to take when faced with a cyberattack.
• Keep your endpoint protection and operating systems updated.
• Implement best practices for Identity and Access Management (IAM).

Detection & Analysis

Organizations should prioritize rapid incident detection and validation to enable effective containment and eradication. Early detection limits the spread of infection and simplifies the response process. During this phase, security teams monitor and analyze alerts and data from systems, networks, and logs to identify potential incidents, understand the threat's scope, impact, and potential source, assess its severity, and gather forensic information. Proper documentation and communication are essential for successful incident response.

Some steps are listed below:

• Alert Monitoring: Collect and monitor data from network, host, and application logs, along with external sources like threat intelligence, to identify attack vectors and signs of potential incidents.
• Incident Identification: Determine whether an event qualifies as an incident or precursor by analyzing and correlating monitoring data.
• Incident Analysis: Classifying the incident type, incident response teams should quickly analyze and validate incidents. Once an incident is confirmed, the team conducts an initial analysis to determine its scope, including affected systems, origin, and attack methods. This analysis helps prioritize actions like containment and deeper investigation.
• Enrichment and Investigation: Gathering additional information (e.g., threat intelligence, forensics analysis) to understand the scope and impact. Maltiverse by Lumu is vital in this procedure.
• Documentation: Recording the details of the incident, timelines, and results of the analysis. An IR team that suspects an incident has occurred should immediately begin recording all facts related to the incident.

How Lumu Helps

Lumu unlocks the value of your own network metadata by implementing the concept of Continuous Compromise Assessment that provides comprehensive and detailed visibility into your network infrastructure. Lumu illuminates the various activities associated with indicators of compromise (IoCs) detected on your network and provides all the contextual information needed for in-depth analysis through the Lumu Portal.

• Lumu Continuous Compromise Assessment technology provides real-time monitoring over network and identity infrastructure. It correlates network and identity metadata to identify anomalies and contact with malicious infrastructure, providing your organization with multiple tools to determine adverse activity.
• Identify activity related to Data Exfiltration incidents and attack patterns. Look for details, such as date, time, number of contacts, IPs, and domains. You have that information at a glance in the Activity section of the Lumu Portal.
• Use the IoC information provided by Lumu to check if the log files of your defensive infrastructure (e.g. endpoint protection, firewall, UTM gateway) contain this malicious communication.
• Identify the endpoints contacting the adversarial infrastructure related to Data Exfiltration incidents. This can be IoCs related to brute force, scanning infrastructure or ransomware gangs. Use the Attack Distribution feature of the Lumu Portal to see how the compromise spreads inside your network.
• Identify how your assets are communicating with the adversarial infrastructure and detect endpoints within the internal network exhibiting anomalous behavior. You can use the Lumu’s Compromise Radar feature to find out the frequency and behavior of malicious communication, so you can differentiate occasional contact from persistent and automated compromises that have the power to cause harm to the organization.
• Use the threat intelligence information provided in each IOC in the Lumu Portal to enrich the context of the activity. Additionally, correlate this with other detections, like Unusual Login, to verify whether the attack attempts were successful. If an incident is confirmed, use this information in incident documentation and analysis.
• If possible, reverse-engineer the malware in a secure environment (or sandbox) to understand its behavior and the functionality it implements.

Containment, Eradication & Recovery

This phase has two key goals: stopping the spread of the threat and preventing further damage within the network. Organizations should implement strategies and procedures based on the risk level of the detected compromise. Containment strategies will vary depending on the type of incident and must consider potential damage or theft of resources, the need for evidence preservation, service availability, and the time and resources required for effective response.

Below are some steps to follow in this phase:

• Containment: Implement immediate actions or long-term strategies to isolate or limit the spread of the incident.
• Eradication: Identify the root cause of the incident and eliminate it.
• Recovery: Recover affected systems to a known good state and confirm normal operations, perform testing to ensure systems are no longer compromised, and prevent future incidents.

How Lumu Helps

Confirmed compromise intelligence about the compromised device helps security analysts to understand where and how to contain and eradicate the compromise.

• Lumu Defender integrates with your security stack and gives your organization the ability to orchestrate an effective automated response to contain any cyber threat, in line with your policies.
• Lumu orchestration can assist you in identifying whether the endpoints that reported the Data Exfiltration were observed displaying anomalous behavior before.
• Use the threat Intelligence information, Mitre ATT&CK TTPs, and IoCs details from Lumu Portal to configure your security infrastructure scheme (firewalls, IDS, IPS, email gateways, etc) to avoid similar malicious activity.
• Lumu Portal provides your organization with information and details about the devices or IP addresses involved in the incident to initiate targeted investigations into the related internal devices.
• Based on your containment strategy, consider isolating the affected devices to prevent lateral movement and limit the spread of the incident within the network
• Identify related services and users and reset the credentials of all involved systems.
• If you suspect the initial attack vector was via email, check the details in the organization's mail server log files.
• Remove threats, and replace or restore the compromised assets to their previous state. Wipe and baseline affected systems if needed.
• Use Lumu technology to establish monitoring to detect further suspicious activity. The incident and its effects need to be remediated across the entire network.
• Complete malware scanning of all systems across the affected network.

Post-Incident Activity

This phase is designed to incorporate the lessons learned from each incident and to evaluate future improvements.

• Lessons Learned: Conduct post-incident reviews to analyze the incident and determine areas for improvement. This step should answer at least the next key questions:
  • What were the root causes of the incident and the incident response issues?
  • Could the incident have been prevented? How?
  • What went well in the incident response?
  • How can we improve our response to future incidents?
• Incident Reporting: Document the incident and share reports with necessary stakeholders.
• Process Improvement: Update policies, procedures, and tools based on findings from the incident.

How Lumu Helps

Lumu helps refine your current and future defense and response by continuously monitoring that the compromise has been eradicated.

• Use Lumu Continuous Compromise Assessment to monitor continuously any communication between your assets and adversarial infrastructure to make sure that no additional contacts are reported.
• Use the context information in the Lumu Portal for details on how the adversary works. Conduct root cause analysis and evaluate the habits of the users.
• Explore the related sources, Mitre ATT&CK Matrix, and articles provided by Lumu in the Context area to understand more about the Tactics, Techniques and Procedures used by adversaries and document the incident.
• Use the incident information to adjust your security policies and Mitre Matrix context to evaluate your security strategy. This may involve changing the configuration of the company's assets and conducting awareness campaigns, focusing on the users that own those devices.
• Coordinate with your endpoint protection technology vendor’s updates if needed.
• Document and share with the stakeholders all the lessons learned from the incident and recommendations of any aspect that could be improved to help prevent a similar cyber incident from reoccurring.