OBFUS_PowerShell_Common_Replace

YARA detection rule by SECUINFRA Falcon Team

Detects the common usage of replace for obfuscation

rule OBFUS_PowerShell_Common_Replace {
	meta:
		author = "SECUINFRA Falcon Team"
		date = "12.02.2022"
		description = "Detects the common usage of replace for obfuscation"

	strings:
		$replace = "replace(" nocase

	condition:
		filesize < 100KB 
		and #replace > 10
}

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

184a9685-82d7-49a1-8c33-31fbad2d61ce

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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