[Tuning] Top Noisy Rules #5449
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[Tuning] Top Noisy Rules #5449
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#1 Multiple Logon Failure from the same Source Address: converted to ES|QL and raised the threshold to 100 failed auths, alert quality should be better since it aggregates all failed auths info into one alert vs multiple EQL matches. (expected reduction more than 50%) #2 Privileged Account Brute Force - coverted to ESQL and set the threshold to 50 in a minute. this should drop noise volume by more than 50%.
Samirbous
added
Rule: Tuning
Contributor
Rule: Tuning - GuidelinesThese guidelines serve as a reminder set of considerations when tuning an existing rule. Documentation and Context
Rule Metadata Checks
Testing and Validation
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Samirbous
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Samirbous
requested review from
Aegrah,
DefSecSentinel,
Mikaayenson,
shashank-elastic,
terrancedejesus and
w0rk3r
terrancedejesus
approved these changes
Dec 11, 2025
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#1 Multiple Logon Failure from the same Source Address: converted to ES|QL and raised the threshold to 100 failed auths, alert quality should be better since it aggregates all failed auths info into one alert vs multiple EQL matches. (expected reduction more than 50%)
#2 Privileged Account Brute Force - coverted to ESQL and set the threshold to 50 in a minute. this should drop noise volume by more than 50%.
#3 Linux Restricted Shell Breakout via Linux Binary(s) - most of the FPs were coming from the
*PAGER*pattern (removed).#4 Command Execution via ForFiles -
-dand/dare the noisiest pattern (excluded) should still trigger on malicious use forfiles /p c:\windows\system32 /m notepad.exe /c "cmd /c c:\windows\system32\calc.exe"#5 Remote File Copy to a Hidden Share: unrelated matches like _movec matching on
*move*or ABCOPY matching on*copy*plus limited rule to cmd/ps and removed xcopy/robocopy used lot in legit copy batch operations.#6 Suspicious Service was Installed in the System - main noisy patterns are windows\temp and psexecsvc and remcomsvc (both are inconclusive for triage and better look for exec /childs from psexec/remcom)
#7 LSASS Process Access via Windows API : converted to ESQL to match on rare instances and removing random patterns from paths should help reduce significantly FPs.
#8 Suspicious Execution via Scheduled Task: few noisy patterns (.bat and .cmd script in cmd.exe args non conclusive for alert triage, excluded also few PS script by path).
#9 Hosts File Modified : main noise comes from Linux with event.action set to rename (which is not indicative of file overwrite) and a set of programfiles for Windows.
#10 Process Termination followed by Deletion - rule scope is an edge case detected by Elastic Defend, expensive correlation (by file.path/process.executable) and starts with a generic process event, marked the rule for deprecation.