Create bypass_edr_syscalls.py for direct syscalls evasion

[kevross33]

Added a new Python file for syscall evasion detection logic (the sig name has been updated as only direct syscalls now), I don't think indirect is possible to cover except maybe the volatility module for them.

Pikabot

[gemini-code-assist]

Summary of Changes

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This pull request enhances the platform's threat detection capabilities by integrating a new signature specifically targeting advanced evasion techniques. It allows for the identification of malicious processes attempting to circumvent security controls by directly invoking system calls, thereby improving the ability to detect sophisticated malware like Pikabot.

Highlights

• New EDR Evasion Detection: Introduced a new Cuckoo signature, SyscallEvasion, designed to identify malware employing direct or indirect syscalls to bypass Endpoint Detection and Response (EDR) and user-land API hooks.
• Syscall Caller Analysis: Implemented logic to analyze the caller address of sysenter calls, distinguishing between legitimate system DLL calls and potentially evasive calls originating from low memory addresses.
• Categorization and Metadata: The new signature is categorized under "evasion" and "stealth", with a severity of 3 and confidence of 80, aligning with MITRE ATT&CK technique T1055.

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Changelog

• modules/signatures/windows/bypass_edr_syscalls.py
  • Added a new Cuckoo signature SyscallEvasion to detect direct and indirect syscalls used for EDR and API hook evasion.
  • Implemented logic to identify evasive syscalls by checking the caller's memory address.
  • Included metadata such as severity, confidence, categories, and MITRE ATT&CK TTPs.

Activity

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[gemini-code-assist]

Code Review

This pull request introduces a new Cuckoo signature to detect EDR evasion through direct or indirect syscalls. The implementation has a critical flaw where it only listens for sysenter, making the 64-bit detection logic unreachable. I've provided a suggestion to fix this. Additionally, I've included a couple of suggestions to refactor parts of the code for better readability and conciseness. Addressing these points will make the signature more robust and maintainable.