BAT_Chunked_Payload_SetEnv

YARA detection rule by marcin@ulikowski.pl · MIT

Detects batch script storing chunks of payload in random environment variables

rule BAT_Chunked_Payload_SetEnv
{
	meta:
		description = "Detects batch script storing chunks of payload in random environment variables"
		author = "marcin@ulikowski.pl"
		date = "2023-05-05"
		hash1 = "f73521adbf89be99c4d7ea74ebf7fed815af49ce4dc060656d7c9c631e4d0538"

	strings:
		$echo = "@echo off"
		$set = { ( 0d 0a | 26 20 ) 73 65 74 20 22 [10] 3d [2-6] 22 }

	condition:
		$echo in (0..4) and
		#set > 10
}

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

bb51f8ad-e565-4e7d-96a3-a02c4d81b22d

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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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