info_nop_sled

YARA detection rule by @shellcromancer · GPL-2.0

Identify a large region of nop'd bytes.

rule info_nop_sled
{
	meta:
		description = "Identify a large region of nop'd bytes."
		author = "@shellcromancer"
		version = "1.0"
		date = "2023.03.07"
		DaysofYARA = "66/100"

	strings:
				$nop = { 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 }

	condition:
		(
			int16(0) == 0x5a4d or      			uint32(0) == 0x464c457f or 			uint32(0) == 0xfeedface or 			uint32(0) == 0xcefaedfe or 			uint32(0) == 0xfeedfacf or 			uint32(0) == 0xcffaedfe or 			uint32(0) == 0xcafebabe or 			uint32(0) == 0xbebafeca    		) and
		any of them
}

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

0d911505-42d6-47e3-9821-faf9e0c8aa2e

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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 ]]

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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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