SIGNATURE_BASE_MAL_APT_Nimbus_Manticore_Stager_May26

rule SIGNATURE_BASE_MAL_APT_Nimbus_Manticore_Stager_May26 : FILE
{
	meta:
		description = "Detects .NET based stager using AppDomain Hijacking observed to be used by Nimbus Manticore (UNC1549). The stager drops another payload and establishes persistence via scheduled task."
		author = "Jonathan Peters (Nextron Systems)"
		id = "5b5e9131-f265-5a91-8390-f1110de75a39"
		date = "2026-05-20"
		modified = "2026-06-01"
		reference = "https://www.nextron-systems.com/2026/06/01/detecting-nimbus-manticore-and-their-sideloading-infection-chains/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_apt35_malware_may26.yar#L18-L47"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "eee657ffdb2af8ed6412221e7d5fbf4f5742f2ac2c88f43f12db46af0697de71"
		logic_hash = "b6ea20370c929a61e628f078ed74c45bd3c7278d3e9c499dbcb9af3f33f23c78"
		score = 80
		quality = 85
		tags = "FILE"

	strings:
		$x1 = "MyCompany-Product-TOTP-Salt-2024!@#$" wide fullword
		$x2 = "TOTPGuardRunner" ascii fullword
		$x3 = "\\AppDomainInjection-metlifeScenario\\TOTP" ascii
		$sa1 = "EncData" ascii fullword
		$sa2 = "DecryptAndSaveToDesktop" ascii fullword
		$sa3 = "CopyHelloToDesktop" ascii fullword
		$sb1 = "doit" wide fullword
		$sb2 = "DailyTrigger" wide fullword
		$sb3 = "GetTypeFromCLSID" ascii
		$sb4 = "yyyy-MM-ddTHH:mm:ss" wide fullword

	condition:
		uint16( 0 ) == 0x5a4d and ( 1 of ( $x* ) or all of ( $sa* ) or all of ( $sb* ) )
}