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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Coralwave_Lenovospkvol_Remcosmicdrop

CoralWave loader masquerading as Lenovo audio DLL. Drops Remcos RAT.

MalwareRemcosSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
xstp
Date
2026-01-01
Modified
2026-05-15
Score / Quality
85 / 85

What this rule detects

CoralWave loader masquerading as Lenovo audio DLL. Drops Remcos RAT.

Associated malware family: Remcos.

Targets: Windows PE.

It defines 9 patterns (9 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-coralwave-lenovospkvol-remcosmicdrop.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Coralwave_Lenovospkvol_Remcosmicdrop : FILE
{
	meta:
		description = "CoralWave loader masquerading as Lenovo audio DLL. Drops Remcos RAT."
		author = "xstp"
		id = "fddc398d-6283-5819-895a-d520aff7088c"
		date = "2026-01-01"
		modified = "2026-05-15"
		reference = "https://bazaar.abuse.ch/sample/050edadedd7947bc6418f7856a29df5b7b5550bf5eec7f5f37e9a7e1713036f6/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/mal_coralwave_remcos_dropper.yar#L1-L30"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "65302b435a5bc30e8f0215455679635ec50b5b1caba9e55f9258d17c7238be54"
		logic_hash = "ec6303584d65cf2138ca44a1cf5e958586d9eee2e9e17a90d0942b1ebee3d01f"
		score = 85
		quality = 85
		tags = "FILE"

	strings:
		$stub_1 = "BAyXuHpAGwdG8ebXF3GvZ32vO3ORY" ascii
		$stub_2 = "IK5HT1XPlj3LoFkKi3YC4QwYQs7s" ascii
		$stub_3 = "Xmk61GHDjDfjUjJhNjwDPXxM1Cdg" ascii
		$fake_1 = "GetVolumeLevel" ascii
		$fake_2 = "OpenSpeakerVolumeInterface" ascii
		$fake_3 = "SetMuteState" ascii
		$mutex = "Rmc-245S33" wide ascii
		$log_file = "logs.dat" wide ascii
		$audio_folder = "MicRecords" wide ascii

	condition:
		filesize < 5MB and uint16( 0 ) == 0x5A4D and ( 2 of ( $stub_* ) or ( 2 of ( $fake_* ) and 1 of ( $mutex , $log_file , $audio_folder ) ) )
}

Strings (9 patterns)

IdentifierTypeValueModifiers
$stub_1text"BAyXuHpAGwdG8ebXF3GvZ32vO3ORY"ascii
$stub_2text"IK5HT1XPlj3LoFkKi3YC4QwYQs7s"ascii
$stub_3text"Xmk61GHDjDfjUjJhNjwDPXxM1Cdg"ascii
$fake_1text"GetVolumeLevel"ascii
$fake_2text"OpenSpeakerVolumeInterface"ascii
$fake_3text"SetMuteState"ascii
$mutextext"Rmc-245S33"wide ascii
$log_filetext"logs.dat"wide ascii
$audio_foldertext"MicRecords"wide ascii

Condition

filesize < 5MB and uint16( 0 ) == 0x5A4D and ( 2 of ( $stub_* ) or ( 2 of ( $fake_* ) and 1 of ( $mutex , $log_file , $audio_folder ) ) )

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 5MB (a cheap guard that skips large files).
  • At least 2 patterns in ( $stub_* ) must match.
  • At least 2 patterns in ( $fake_* ) must match.
  • At least 1 patterns in ( $mutex , $log_file , $audio_folder ) must match.

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References

Sample hashes

Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).

  • 65302b435a5bc30e8f0215455679635ec50b5b1caba9e55f9258d17c7238be54

Licence & attribution

Author: xstp

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

Licence: Detection Rule License 1.1 (repository licence)

Original rule

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

Rule id: fddc398d-6283-5819-895a-d520aff7088c

Tags:FILE

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