YARA · ESET malware-ioc

ESET_Apt_Windows_Invisimole_SFX_Dropper

Detects trojanized InvisiMole files: patched RAR SFX droppers with added InvisiMole blobs (config encrypted XOR 2A at the end of a file)

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

Author: ESET Research
Date: 2021-05-17
Score / Quality: 75 / 80

What this rule detects

Detects trojanized InvisiMole files: patched RAR SFX droppers with added InvisiMole blobs (config encrypted XOR 2A at the end of a file)

Associated malware family: Invisimole.

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-windows-invisimole-sfx-dropper.yarBSD 2-Clause License

rule ESET_Apt_Windows_Invisimole_SFX_Dropper : FILE
{
	meta:
		description = "Detects trojanized InvisiMole files: patched RAR SFX droppers with added InvisiMole blobs (config encrypted XOR 2A at the end of a file)"
		author = "ESET Research"
		id = "08490bcd-3139-5fac-9c6c-5a32acb7217a"
		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#L79-L95"
		license_url = "https://github.com/eset/malware-ioc/blob/17baf44964a77368e9149f4f593eb098beddf1c5/LICENSE"
		logic_hash = "6ca248d42c1e889988e5931d80df071cb20e623fb0c4a208044cabe073f71ce4"
		score = 75
		quality = 80
		tags = "FILE"
		license = "BSD 2-Clause"
		version = "1"

	strings:
		$encrypted_config = {5F 59 4F 58 19 18 04 4E 46 46 2A 5D 59 5A 58 43 44 5E 4C 7D 2A 0F 2A 59 2A 78 2A 4B 2A 58 2A 0E 2A 6F 2A 72 2A 4B 2A 0F 2A 4E 2A 04 2A 0F 2A 4E 2A 76 2A 0F 2A 79 2A 2A 2A 79 42 4F 46 46 6F 52 4F 49 5F 5E 4F 7D 2A 79 42 4F 46 46 19 18 04 4E 46 46 2A 7C 43 58 5E 5F 4B 46 6B 46 46 45 49 2A 66 45 4B 4E 66 43 48 58 4B 58 53 6B}

	condition:
		uint16( 0 ) == 0x5A4D and $encrypted_config
}

Strings (1 patterns)

Identifier	Type	Value	Modifiers
$encrypted_config	hex	{5F 59 4F 58 19 18 04 4E 46 46 2A 5D 59 5A 58 43 44 5E 4C 7D 2A 0F 2A 59 2A 78 2A 4B 2A 58 2A 0E 2A 6F 2A 72 2A 4B 2A 0F 2A 4E 2A 04 2A 0F 2A 4E 2A 76 2A 0F 2A …

Condition

uint16( 0 ) == 0x5A4D and $encrypted_config

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
Pattern $encrypted_config must be present.

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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: 08490bcd-3139-5fac-9c6c-5a32acb7217a

Metadata

version	1

Tags:FILE

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