[Enhancement] PowerShell - Optimize Entropy Calculation, Add Normalized Entropy, Add Pipeline Benchmark#16707
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[Enhancement] PowerShell - Optimize Entropy Calculation, Add Normalized Entropy, Add Pipeline Benchmark#16707
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Pinging @elastic/sec-windows-platform (Team:Security-Windows Platform) |
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Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane) |
mauri870
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Jan 5, 2026
mauri870
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Jan 5, 2026
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LGTM, but I'm not very proficient with PowerShell. The code looks fine, but it needs a deeper look from the Windows team.
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| double normalizedEntropy = 0.0; | ||
| if (length > 1) { | ||
| double maxEntropy = Math.log((double) length) * invLog2; // max bits if every character is unique |
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I think the normalized entropy calculation looks good 👍
Few notes for posterity:
- For the line
double maxEntropy = Math.log((double) length) * invLog2; // max bits if every character is uniqueI think it makes sense to use length here. Typical normalized entropy calculations (like that for R/Posterior ref) would use something akin toseenCountinstead oflength. However, this is expecting the input to be more akin to categories whereaandaare equivalent regardless of their position in the script block. In our case, I think we want the position to mater as well, so each value is by definition unique makinglengththe correct number to use here (as is correctly done in the code). - The pre-output check
else if (normalizedEntropy > 1.0) normalizedEntropy = 1.0;I think is technically not necessary, as this should not occur. However, I think we should keep this check as it could catch floating point rounding issues without impacting the integrity of the data result (code is correct as is).
nfritts
approved these changes
Jan 23, 2026
🚀 Benchmarks reportTo see the full report comment with |
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cc @w0rk3r |
gogochan
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Jan 23, 2026
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Package windows - 3.4.0 containing this change is available at https://epr.elastic.co/package/windows/3.4.0/ |
jakubgalecki0
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Feb 19, 2026
…ed Entropy, Add Pipeline Benchmark (elastic#16707) * [Enhancement] PowerShell - Optimize Entropy Calculation, Add Normalized Entropy, Add Pipeline Benchmark * Update test-powershell-operational-events.json-expected.json * Update changelog.yml * rename benchmark file
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Proposed commit message
Summary
Related issue:
This PR:
powershell.file.script_block_entropy_normalized= entropy_bits / log2(script_block_length) (0–1).Old pipeline:
Improved pipeline:
Complete benchmark output
Old:
Improved:
Checklist
changelog.ymlfile.