Create sig for likely ransomware asynchronous encryption

[kevross33]

Lockbit

[gemini-code-assist]

Summary of Changes

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This pull request introduces a new detection mechanism aimed at identifying ransomware that utilizes asynchronous encryption techniques. By observing the binding of numerous files to I/O Completion Ports, the new signature helps to flag suspicious processes that might be encrypting user data, thereby enhancing the system's ability to detect and respond to ransomware threats.

Highlights

• New Ransomware Signature: A new signature, RansomwareIOCPAsynchronousEncryption, has been added to detect potential ransomware activity. This signature focuses on the binding of a large number of files to I/O Completion Ports (IOCP), which is indicative of asynchronous encryption often used by ransomware.
• IOCP File Monitoring: The signature monitors NtSetInformationFile calls to identify when files are associated with IOCP. It tracks unique file paths and triggers if more than 50 distinct files are bound to IOCP, indicating suspicious behavior.
• Ransomware TTP Mapping: The signature is mapped to MITRE ATT&CK technique T1486 (Data Encrypted for Impact), categorizing it under 'ransomware' with a severity of 4 and confidence of 80.

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Changelog

• modules/signatures/windows/ransomware_asynchronous_encryption.py
  • Added new signature file for ransomware detection.

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[gemini-code-assist]

Code Review

This pull request introduces a new Cuckoo signature for detecting potential ransomware activity that uses asynchronous encryption with I/O Completion Ports. The overall logic is good. I've provided a few suggestions to improve the code's readability and maintainability by removing an unused variable, simplifying a conditional statement, and refactoring a method to be more concise.