SEKOIA_Apt_Kimsuky_Powershell_Dropper_Strings

rule SEKOIA_Apt_Kimsuky_Powershell_Dropper_Strings : FILE
{
	meta:
		description = "Detects a PowerShell dropper used by Kimsuky"
		author = "Sekoia.io"
		id = "8b346e05-215b-46c0-82bf-fce3a65440f3"
		date = "2024-06-11"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_kimsuky_powershell_dropper_strings.yar#L1-L21"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "e98f23ddf02049126786e9300e7b6661b2a74817b36e2f3a661b07b24ef4402d"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$s1 = "try { " ascii wide
		$s2 = "); } catch(e){} } if ("
		$s3 = "WScript.Sleep("
		$s4 = " } catch(e) { }"

	condition:
		filesize > 500KB and $s1 at 0 and $s2 in ( filesize -1000 .. filesize ) and $s3 in ( filesize -1000 .. filesize ) and $s4 in ( filesize -1000 .. filesize )
}