Update NitroBunnyDownloader yara

[enzok]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @enzok, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on strengthening the detection of NitroBunnyDownloader malware by refining its associated YARA rule. The update involves adding a new configuration pattern and adjusting the matching condition to ensure that the rule can identify a wider range of variants or obfuscation techniques, ultimately improving the accuracy and reliability of threat identification.

Highlights

• YARA Rule Update: The YARA rule for NitroBunnyDownloader has been updated to enhance its detection capabilities.
• New Configuration Pattern: An additional configuration pattern, $config2, has been introduced to the rule's strings section.
• Improved Matching Logic: The rule's condition has been modified to require at least one of the defined configuration patterns ($config*) to match, making the detection more robust.

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[gemini-code-assist]

Code Review

This pull request updates the NitroBunnyDownloader YARA rule by adding a new variant for a byte pattern to improve detection. The changes are correct, but I've suggested a refinement. My feedback focuses on combining the two similar byte patterns into a single one using an alternation. This will make the rule more concise, readable, and potentially more performant. This requires a corresponding change in the condition section, which I have also included.

[gemini-code-assist]

The two $config patterns are very similar and only differ in the order of two instruction sequences. You can combine them into a single, more efficient pattern using an alternation |. This improves readability and can be more performant for the YARA engine.

        $config = {E8 [3] 00 ( 41 B8 ?? ?? 00 00 48 8D 15 [3] 00 | 48 8D 15 [3] 00 41 B8 ?? ?? 00 00 ) 48 89 C1 48 89 ?? E8 [3] 00}

[gemini-code-assist]

Following the suggestion to combine the $config patterns, the condition should be updated to refer to the new single $config pattern instead of checking for 1 of ($config*).

        uint16(0) == 0x5A4D and $config and 2 of ($string*)