fix: reduce Windows Defender false positive on fileless malware skill - #112
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kevglynn wants to merge 2 commits into
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fix: reduce Windows Defender false positive on fileless malware skill#112kevglynn wants to merge 2 commits into
kevglynn wants to merge 2 commits into
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Add AV false-positive guidance for issue mukul975#100, move inline YARA rule to references/yara-fileless-powershell.yar, and replace literal encoded PowerShell payload with a placeholder in the sample report.
The --yara-file reference should not assume a specific working directory. Use a placeholder path that analysts will substitute for their setup.
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Summary
Addresses #100 — Windows Defender quarantines
detecting-fileless-malware-techniques/SKILL.mdasTrojan:script/Wacatac.H!ml. The skill content is defensive/educational; the detection is a false positive caused by literal malware-pattern strings embedded in documentation.Scope and limitations: This PR reduces the triggering surface by removing the highest-signal tokens (inline YARA rules with literal malware strings, a Base64-encoded PowerShell payload sample). However,
SKILL.mdintentionally retains educational references to LOLBin abuse patterns,Invoke-Mimikatz, CobaltStrike, andAMSI bypass— these are core to the skill's purpose and cannot be sanitized without gutting the content. This PR may reduce but not eliminate false positives. The primary deliverable is the discoverability section so users who hit this know it's a known issue and how to resolve it.Changes:
references/yara-fileless-powershell.yar(preserves the rule for analysts, reduces scanner hits onSKILL.md)<BASE64_UTF16LE_PAYLOAD>placeholder in the worked reportstringsgrep examplesTest plan
python3 tools/validate-skill.py skills/detecting-fileless-malware-techniques→ PASSpython3 tools/validate-skill.py --all→ 817/817 PASSMitigates #100