YARA · Trellix Advanced Research Center

TRELLIX_ARC_Nefilim_Ransomware

Rule to detect Nefilim ransomware

MalwareNefilimTrellix Advanced Research CenterApache License 2.0Compile avec YARA-X

Auteur: Marc Rivero | McAfee ATR Team
Date: 2020-03-17
Modifiée: 2020-04-03
Score / Qualité: 75 / 70

Ce que détecte cette règle

Rule to detect Nefilim ransomware

Famille de malware associée : Nefilim.

Cibles : PE Windows.

Elle définit 8 motifs (4 texte, 4 hex, 0 regex).

Résumé généré à partir des métadonnées et de la condition de la règle.

Source de la règle

Télécharger .yar

nefilim-ransomware.yarApache License 2.0

rule TRELLIX_ARC_Nefilim_Ransomware : RANSOMWARE FILE
{
	meta:
		description = "Rule to detect Nefilim ransomware"
		author = "Marc Rivero | McAfee ATR Team"
		id = "55d9cb20-5071-5dce-a46f-a20816ba379f"
		date = "2020-03-17"
		modified = "2020-04-03"
		reference = "https://www.bleepingcomputer.com/news/security/new-nefilim-ransomware-threatens-to-release-victims-data/"
		source_url = "https://github.com/advanced-threat-research/Yara-Rules//blob/1919562a59f190bda60c982424f6a24c542ee3e0/ransomware/RANSOM_NEFILIM.yar#L3-L48"
		license_url = "https://github.com/advanced-threat-research/Yara-Rules//blob/1919562a59f190bda60c982424f6a24c542ee3e0/LICENSE"
		hash = "5ab834f599c6ad35fcd0a168d93c52c399c6de7d1c20f33e25cb1fdb25aec9c6"
		logic_hash = "d8cd5d2dd552d3e9f57f7bd244e941fe89a96ab16bbcc71911e8e2a519f53f03"
		score = 75
		quality = 70
		tags = "RANSOMWARE, FILE"
		rule_version = "v1"
		malware_type = "ransomware"
		malware_family = "Ransom:W32/Nefilim"
		actor_type = "Cybercrime"
		actor_group = "Unknown"

	strings:
		$s1 = "C:\\Users\\Administrator\\Desktop\\New folder\\Release\\NEFILIM.pdb" fullword ascii
		$s2 = "oh how i did it??? bypass sofos hah" fullword ascii
		$s3 = " /c timeout /t 3 /nobreak && del \"" fullword wide
		$s4 = "NEFILIM-DECRYPT.txt" fullword wide
		$op0 = { db ff ff ff 55 8b ec 83 ec 24 53 56 57 89 55 f4 }
		$op1 = { 60 be 00 d0 40 00 8d be 00 40 ff ff 57 eb 0b 90 }
		$op2 = { 84 e0 40 00 90 d1 40 00 08 }
		$bp = { 558B??83????53565789????29????6A??8D????8D????5A8B??89????8A????88????8B????8A????88??8A????88????8A??88????03??03??FF????75??89????8D????8D????8D????89????89????29????89????29????89????29????8D????8D????89????29????89????29????8B????89????29????8D????F6??????8B????8A????8B????8A????8A??88????8B????8A????88????75??0FB6??8A??????????0FB6??88????8A??????????0FB6????8A??????????88????0FB6????8A??????????88????8B????C1????32??????????8B????8A????32??8B????88????8A????32??88????8A??32????83????88????8B????8A????32????FF????88??83????83????83??????0F82????????5F5E5BC9C3558B??560FB6??57C1????03????6A??5F6A??5E8A??30??40414E75??4F75??5F5E5DC356576A??5F6A??8B??5E0FB6??8A??????????88??83????4E75??414F75??5F5EC38A????8A????88????8A????88????8A????88????8A????88????8A????88????8A????88????8A????88????8A????88????8A????88????8A????88????8A????88????88????C3558B??5153566A??83????5E8A????32??8A????8A????88????32??32??88????88????32??8A??C0????B3??F6??02??32??32????8A????32????32??88????8A??C0????F6??02??32??32????8A????32????88????8A??C0????F6??02??32??32??8A????32????32????88??8A??C0????F6??02??32??32????83????32????4E88????75??5E5BC9C3558B??53FF????8B??32??E8????????59B3??8B??E8????????8B??E8????????8B??E8????????FF????8B??8A??E8????????FE??5980????72??8B??E8????????8B??E8????????5B8B??B0??5DE9????????558B??81??????????53568D??????????E8????????33??6A??5939????76??5783????75??8B????8D????A5A5A58D??????????A5508D????E8????????596A??588B????8D????80????75??48C6????79??EB??FE????33??8A??????8B????30????43413B????72??5F8B????8B????6A??2B??5E8A????88??404E75??5E5BC9C3558B??81??????????53FF????8D??????????50FF??????????68????????8D??????????50FF??????????33??53536A??535368????????8D??????????50FF??????????89????3B??0F84????????56578D????5053BE????????5689????FF??????????5056E8????????83????85??75??53FF??????????FF????8B??????????53FF??50FF??????????8D????51505689????FF??????????5056E8????????83????85??74??8B????89????8D????50FF????E8????????59595385??74??8D????50FF????FF????FF????FF??????????FF????53FF??50FF??????????5F5E5BC9C3558B??83????81??????????535657FF????8D????????????50FF??????????8B??????????68????????8D????????????50FF??8D??????508D????????????50FF??????????89??????83????0F84????????8B??????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????68????????8D??????50FF??85??0F84????????F6????????FF????8D????????????5074??FF??????????8D??????508D????????????50FF??68????????8D????????????50FF??8D????????????50E8????????E9????????FF??????????8D??????508D????????????50FF??8D??????50E8????????8B??C7????????????57FF??85??0F84????????68????????57FF??85??0F84????????68????????57FF??85??0F84????????68????????57FF??85??0F84????????68????????57FF??85??0F84????????68????????57FF??85??0F84????????68????????57FF??85??0F84????????68????????57FF??85??74??68????????57FF??85??74??68????????57FF??85??74??68????????57FF??85??74??68????????57FF??85??74??68????????57FF??85??74??68????????57FF??85??74??68????????57FF??85??74??68????????57FF??85??74??68????????8D??????50FF??85??74??8D????????????50E8????????598D??????50FF??????FF??????????85??0F85????????FF??????FF??????????5F5E5B8B??5DC3558B??81??????????53565768????????FF??????????8B??????????5033??57FF??8B??????????50FF??68????????89????FF??????????89????B8????????39????74??8B????2B??8A??FF????88????4039????75??57576A??575768????????FF????FF??????????89????3B??0F84????????8D????5150FF??????????6A??57FF??50FF??6A??5789????FF??50FF??FF????89????E8????????FF????E8????????595968????????57FF??50FF??68????????5789????FF??50FF??FF????8B????89????E8????????FF????8B????E8????????8B??????????59595757FF????FF????FF????FF??57FF??????????578D????5068????????FF????FF????FF??????????FF??????????83????0F84????????FF??????????83????0F84????????8B????8B????5705????????5713??5150FF????FF??578D????5068????????FF????FF????FF??????????8B????8B????5705????????5713??5150FF????FF??578D????5068????????FF??????????50FF????FF????FF??????????8B????8B????3B??0F8C????????7F??81??????????0F86????????89????89????3B??0F8C????????7F??3B??0F86????????EB??8B????2B????1B????89????0F88????????7F??81??????????0F82????????68????????57FF??50FF??????????5757FF????89????FF????FF????FF??578D????5068????????FF????FF????FF??????????FF????8B????FF????68????????FF????E8????????83????5757FF????FF????FF????FF??578D????5068????????FF????FF????FF??????????FF??FF????5750FF??????????81????????????8B????11????39????0F8C????????0F8F????????8B????39????0F82????????E9????????3B??7C??7F??81??????????76??68????????57FF??50FF??????????575733??89????5133??50FF????FF??578D????5068????????FF????FF????FF??????????FF????8B????FF????68????????FF????E8????????83????575733??5050FF????FF??578D????5068????????EB??5157FF??50FF??????????575733??89????5133??50FF????FF??578D????50FF????FF????FF????FF??????????FF????8B????FF????FF????FF????E8????????83????575733??5050FF????FF??578D????50FF????FF????FF????FF??????????FF????57FF??50FF??????????FF????FF??????????FF????57FF??8B??????????50FF??FF???? }

	condition:
		uint16( 0 ) == 0x5a4d and filesize < 200KB and all of ( $s* ) or all of ( $op* ) or $bp
}

Chaînes (8 motifs)

Identifiant	Type	Valeur	Modificateurs
$s1	texte	"C:\\Users\\Administrator\\Desktop\\New folder\\Release\\NEFILIM.pdb"	fullword ascii
$s2	texte	"oh how i did it??? bypass sofos hah"	fullword ascii
$s3	texte	" /c timeout /t 3 /nobreak && del \""	fullword wide
$s4	texte	"NEFILIM-DECRYPT.txt"	fullword wide
$op0	hex	{ db ff ff ff 55 8b ec 83 ec 24 53 56 57 89 55 f4 }
$op1	hex	{ 60 be 00 d0 40 00 8d be 00 40 ff ff 57 eb 0b 90 }
$op2	hex	{ 84 e0 40 00 90 d1 40 00 08 }
$bp	hex	{ 558B??83????53565789????29????6A??8D????8D????5A8B??89????8A????88????8B????8A????88??8A????88????8A??88????03??03??FF????75??89????8D????8D????8D????89????89 …

Condition

uint16( 0 ) == 0x5a4d and filesize < 200KB and all of ( $s* ) or all of ( $op* ) or $bp

En clair (Heuristique)

Le fichier doit commencer par « MZ » — un exécutable Windows (PE).
Le fichier doit faire moins de 200KB (garde-fou peu coûteux qui écarte les gros fichiers).
Tous les motifs de ( $s* ) doivent être trouvés.
Tous les motifs de ( $op* ) doivent être trouvés.
Le motif $bp doit être présent.

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Ouvrir dans l’éditeur

Références

https://www.bleepingcomputer.com/news/security/new-nefilim-ransomware-threatens-to-release-victims-data/

Hashes d’échantillons

Hashes des échantillons listés par l’auteur dans les métadonnées de la règle (à rechercher dans votre plateforme de threat intelligence).

5ab834f599c6ad35fcd0a168d93c52c399c6de7d1c20f33e25cb1fdb25aec9c6

Licence et attribution

Auteur : Marc Rivero | McAfee ATR Team

Dépôt source : Trellix Advanced Research Center @ 1919562a59

Licence : Apache License 2.0 (licence du dépôt)

Règle d’origine

Reprise via YARA Forge 20260927, qui préfixe les noms de règles par la source et ajoute des champs meta normalisés.

Identifiant de règle: 55d9cb20-5071-5dce-a46f-a20816ba379f

Métadonnées

rule_version	v1
malware_type	ransomware
malware_family	Ransom:W32/Nefilim
actor_type	Cybercrime
actor_group	Unknown

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