Scenario: Detecting and Mitigating a Ransomware Attack

April 2025

A ransomware attack encrypts files and demands payment for decryption. Attackers often use phishing emails, exploit vulnerabilities, or leverage compromised credentials to deploy ransomware.

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1. Initial Threat Detection

• Endpoint security sensors detect suspicious file encryption activity on a workstation.

• Network security monitors log high-volume outbound traffic to an unknown IP, suggesting data exfiltration.

• The XDR system correlates these events, recognizing the pattern as a potential ransomware infection.

Detection Sources

1. Endpoint Logs:

   • Rapid changes to file extensions, encrypted documents, and mass renaming.

   • Execution of unknown or unauthorized processes.

2. Network Traffic Analysis:

   • Outbound connections to command-and-control (C2) servers.

   • High data transfer rates to suspicious IPs.

3. SIEM & Log Analysis:

   • Event ID 4663 (file access attempts) indicating mass encryption.

   • Event ID 5145 (network share access) suggesting lateral movement.

4. Email Security Logs:

   • A recent phishing email containing a malicious attachment was delivered, potentially initiating the attack.

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2. Data Collection & Correlation

• The XDR platform aggregates logs from multiple sources:

  • Endpoint activity logs revealing encryption patterns.

  • Network logs identifying outbound communication with ransomware operators.

  • Email security logs linking the attack to a phishing email.

  • Authentication logs tracking privilege escalations or compromised accounts.

• Machine learning-based threat correlation helps reconstruct the attack timeline, pinpointing the initial infection vector.

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3. Automated Response Actions

1. Immediate Isolation:

   • Disconnects the infected workstation from the network to contain the spread.

2. Malicious IP Blocking:

   • Halts data exfiltration by severing contact with the C2 server.

3. Account Suspension:

   • Revokes access for compromised accounts to prevent further escalation.

4. Security Team Alert:

   • XDR generates high-fidelity forensic alerts, providing detailed recommendations for investigation and mitigation.

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4. Investigation & Security Reinforcement

Steps:

• Identify the ransomware strain by analyzing encrypted files and payload execution.

• Verify data integrity by assessing recent backups for restoration.

• Conduct organization-wide scans to detect additional compromised endpoints.

• Improve security policies by strengthening email security, blocking related malware signatures, and enforcing stricter access controls.

Mitigation & Hardening:

1. Implement Endpoint Protection:

   • Use EDR (Endpoint Detection and Response) to monitor and block ransomware executions proactively.

2. Enhance Backup Strategies:

   • Maintain offline backups for secure data recovery.

3. Restrict Privileged Access:

   • Apply the least privilege model to limit ransomware impact.

4. Improve Email Security:

   • Enforce advanced phishing protection and conduct user training to prevent future attacks.

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Outcome

✅ Ransomware attack mitigated before widespread file encryption occurs. ✅ Data exfiltration blocked before ransom demands. ✅ Affected systems restored using backups, eliminating the need for negotiations. ✅ Security teams gain forensic insights to improve future defenses.