YARA · ESET malware-ioc

ESET_Apt_Windows_Invisimole_RC2CL_Backdoor

InvisiMole RC2CL backdoor

APT / threat actorInvisimoleESET malware-iocBSD 2-Clause LicenseCompiles with YARA-X

Author: ESET Research
Date: 2021-05-17
Score / Quality: 75 / 78

What this rule detects

InvisiMole RC2CL backdoor

Associated malware family: Invisimole.

Targets: Windows PE.

It defines 22 patterns (21 text, 1 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

Includes the imports and 1 rule(s) it depends on needed to compile it on its own.

apt-windows-invisimole-rc2cl-backdoor.yarBSD 2-Clause License

private rule ESET_Invisimole_Blob_PRIVATE
{
	meta:
		description = "Detects InvisiMole blobs by magic values"
		author = "ESET Research"
		id = "6a179d91-50f1-5400-b141-0f162efd2431"
		date = "2021-05-17"
		modified = "2021-05-17"
		reference = "https://github.com/eset/malware-ioc/"
		source_url = "https://github.com/eset/malware-ioc/blob/17baf44964a77368e9149f4f593eb098beddf1c5/invisimole/invisimole.yar#L34-L52"
		license_url = "https://github.com/eset/malware-ioc/blob/17baf44964a77368e9149f4f593eb098beddf1c5/LICENSE"
		logic_hash = "8bddaf874da58fbe6362498f8979b511f39531fe2b98d4be8c099bdafb6d0067"
		score = 75
		quality = 80
		tags = ""
		license = "BSD 2-Clause"
		version = "1"

	strings:
		$magic_old_32 = {F9 FF D0 DE}
		$magic_old_64 = {64 FF D0 DE}
		$magic_new_32 = {86 DA 11 CE}
		$magic_new_64 = {64 DA 11 CE}

	condition:
		($magic_old_32 at 0 ) or ( $magic_old_64 at 0 ) or ( $magic_new_32 at 0 ) or ( $magic_new_64 at 0 )
}

rule ESET_Apt_Windows_Invisimole_RC2CL_Backdoor : FILE
{
	meta:
		description = "InvisiMole RC2CL backdoor"
		author = "ESET Research"
		id = "0228b8ee-bf03-504e-8cdf-8a1c9a79d54e"
		date = "2021-05-17"
		modified = "2021-05-17"
		reference = "https://github.com/eset/malware-ioc/"
		source_url = "https://github.com/eset/malware-ioc/blob/17baf44964a77368e9149f4f593eb098beddf1c5/invisimole/invisimole.yar#L172-L213"
		license_url = "https://github.com/eset/malware-ioc/blob/17baf44964a77368e9149f4f593eb098beddf1c5/LICENSE"
		logic_hash = "c38550023515d33eaaf0669cc8b874bcfd09653a07c7edbf72e3344d1cf31541"
		score = 75
		quality = 78
		tags = "FILE"
		license = "BSD 2-Clause"
		version = "1"

	strings:
		$s1 = "RC2CL" wide
		$s2 = "hp12KsNh92Dwd" wide
		$s3 = "ZLib package %s: files: %d, total size: %d" wide
		$s4 = "\\Un4seen" wide
		$s5 = {9E 01 3A AD}
		$s6 = "~mrc_" wide
		$s7 = "~src_" wide
		$s8 = "~wbc_" wide
		$s9 = "zdf_" wide
		$s10 = "~S0PM" wide
		$s11 = "~A0FM" wide
		$s12 = "~70Z63\\" wide
		$s13 = "~E070C" wide
		$s14 = "~N031E" wide
		$s15 = "%szdf_%s.data" wide
		$s16 = "%spicture.crd" wide
		$s17 = "%s70zf_%s.cab" wide
		$s18 = "%spreview.crd" wide
		$s19 = "Value_Bck" wide
		$s20 = "Value_WSFX_ZC" wide
		$s21 = "MachineAccessStateData" wide
		$s22 = "SettingsSR2" wide

	condition:
		(( uint16( 0 ) == 0x5A4D ) or ESET_Invisimole_Blob_PRIVATE ) and 5 of ( $s* )
}

Strings (22 patterns)

Identifier	Type	Value	Modifiers
$s1	text	"RC2CL"	wide
$s2	text	"hp12KsNh92Dwd"	wide
$s3	text	"ZLib package %s: files: %d, total size: %d"	wide
$s4	text	"\\Un4seen"	wide
$s5	hex	{9E 01 3A AD}
$s6	text	"~mrc_"	wide
$s7	text	"~src_"	wide
$s8	text	"~wbc_"	wide
$s9	text	"zdf_"	wide
$s10	text	"~S0PM"	wide
$s11	text	"~A0FM"	wide
$s12	text	"~70Z63\\"	wide
$s13	text	"~E070C"	wide
$s14	text	"~N031E"	wide
$s15	text	"%szdf_%s.data"	wide
$s16	text	"%spicture.crd"	wide
$s17	text	"%s70zf_%s.cab"	wide
$s18	text	"%spreview.crd"	wide
$s19	text	"Value_Bck"	wide
$s20	text	"Value_WSFX_ZC"	wide
$s21	text	"MachineAccessStateData"	wide
$s22	text	"SettingsSR2"	wide

Condition

(( uint16( 0 ) == 0x5A4D ) or ESET_Invisimole_Blob_PRIVATE ) and 5 of ( $s* )

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
At least 5 patterns in ( $s* ) must match.
Depends on the rule ESET_Invisimole_Blob_PRIVATE.

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References

https://github.com/eset/malware-ioc/

Licence & attribution

Author: ESET Research

Source repository: ESET malware-ioc @ 17baf44964

Licence: BSD 2-Clause License (stated in the rule's own meta)

“BSD 2-Clause”

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: 0228b8ee-bf03-504e-8cdf-8a1c9a79d54e

Metadata

version	1

Tags:FILE

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