How to Detect and Analyze Ransomware Activity Using Logs

Ransomware attacks encrypt files and demand a ransom for decryption, often spreading across networks and disabling recovery mechanisms. Detecting ransomware requires analyzing logs for abnormal activity patterns related to file changes, processes, and network behavior.

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1. Monitor for Mass File Encryption Activity

What to Look For:

• File System Logs:

  • Logs showing a high volume of file modifications or creations in a short timeframe.

  • Event ID 4663: Captures access attempts to files and objects.

• File Extensions:

  • Sudden renaming of files with unusual or consistent extensions (e.g., .locky, .crypt, .encrypted).

Red Flags: Bulk modifications of files in user directories or shared drives.

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2. Check for Suspicious Process Activity

What to Look For:

• Process Creation Events:

  • Event ID 4688: Logs process creation details. Look for:

    • Known ransomware executables or unusual process names.

    • Processes executing from non-standard directories (e.g., %AppData%, %Temp%).

• Child Process Activity:

  • Processes spawning multiple child processes, which may indicate encryption or payload distribution.

Red Flags: Processes running encoded or obfuscated commands or executing from user directories.

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3. Investigate Volume Shadow Copy Deletion

What to Look For:

• Shadow Copy Deletion Commands:

  • Logs showing the execution of vssadmin delete shadows or similar commands used to remove backup copies.

• Key Event IDs:

  • Event ID 528: Logs storage deletion events.

Red Flags: Deletion of shadow copies or backups, which ransomware often does to disable recovery.

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4. Analyze Network Activity

What to Look For:

• Unusual SMB Traffic:

  • Event ID 5140: Captures network share access. Look for:

    • Unusual or excessive access to administrative shares (C$, ADMIN$).

    • Machines accessing multiple network shares rapidly.

• Propagation Behavior:

  • Logs showing lateral movement attempts via SMB, RDP, or similar protocols.

Red Flags: Large-scale access to shared drives, especially from unexpected systems.

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5. Review for Ransom Notes or New Files

What to Look For:

• File Creation Logs:

  • Event ID 4663: Detects the creation of new files, such as ransom notes (README.txt, DECRYPT_INSTRUCTIONS.txt).

• Unusual File Activity:

  • Files with consistent names appearing across multiple directories.

Red Flags: Sudden appearance of ransom note files in affected directories.

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6. Immediate Response

What to Do:

• Isolate Affected Systems: Disconnect compromised machines from the network to prevent further spread.

• Disable Network Access: Block network shares and access points being used by the ransomware.

• Initiate Incident Response Procedures:

  • Notify the security team and relevant stakeholders.

  • Begin forensic analysis to determine the scope of the attack.

• Ensure Backup Integrity: Verify that backups are intact and uninfected before initiating recovery.

• Notify Law Enforcement: Report the incident if required by regulatory or legal frameworks.

Post-Incident Steps:

• Patch Systems: Address vulnerabilities that allowed the ransomware to execute or spread.

• Enhance Monitoring: Deploy detection rules to identify similar activities in the future.

• Educate Employees: Conduct training to reduce the risk of phishing or other attack vectors often used to deliver ransomware.

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Conclusion

Detecting ransomware activity requires monitoring logs for file system changes, process anomalies, and network propagation behavior. Early detection and swift response are critical to minimizing damage and ensuring recovery.

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