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YARA · Trellix Advanced Research Center

TRELLIX_ARC_Ransom_Linux_Hellokitty_0721

rule to detect Linux variant of the Hello Kitty Ransomware

MalwareHelloKittyTrellix Advanced Research CenterApache License 2.0Compiles with YARA-X
Author
Christiaan @ ATR
Date
2021-07-19
Score / Quality
75 / 70

What this rule detects

rule to detect Linux variant of the Hello Kitty Ransomware

Associated malware family: HelloKitty.

It defines 11 patterns (11 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

ransom-linux-hellokitty-0721.yarApache License 2.0
rule TRELLIX_ARC_Ransom_Linux_Hellokitty_0721 : RANSOMWARE FILE
{
	meta:
		description = "rule to detect Linux variant of the Hello Kitty Ransomware"
		author = "Christiaan @ ATR"
		id = "097b02e7-93d8-5d4f-9964-7b660b3cd7b9"
		date = "2021-07-19"
		modified = "2021-07-19"
		reference = "https://github.com/advanced-threat-research/Yara-Rules/"
		source_url = "https://github.com/advanced-threat-research/Yara-Rules//blob/1919562a59f190bda60c982424f6a24c542ee3e0/ransomware/RANSOM_Linux_HelloKitty0721.yar#L1-L28"
		license_url = "https://github.com/advanced-threat-research/Yara-Rules//blob/1919562a59f190bda60c982424f6a24c542ee3e0/LICENSE"
		hash = "ca607e431062ee49a21d69d722750e5edbd8ffabcb54fa92b231814101756041"
		hash = "556e5cb5e4e77678110961c8d9260a726a363e00bf8d278e5302cb4bfccc3eed"
		logic_hash = "77a3809df4c7c591a855aaecd702af62935952937bb81661aa7f68e64dcf4fb4"
		score = 75
		quality = 70
		tags = "RANSOMWARE, FILE"
		Rule_Version = "v1"
		malware_type = "ransomware"
		malware_family = "Ransom:Linux/HelloKitty"

	strings:
		$v1 = "esxcli vm process kill -t=force -w=%d" fullword ascii
		$v2 = "esxcli vm process kill -t=hard -w=%d" fullword ascii
		$v3 = "esxcli vm process kill -t=soft -w=%d" fullword ascii
		$v4 = "error encrypt: %s rename back:%s" fullword ascii
		$v5 = "esxcli vm process list" fullword ascii
		$v6 = "Total VM run on host:" fullword ascii
		$v7 = "error lock_exclusively:%s owner pid:%d" fullword ascii
		$v8 = "Error open %s in try_lock_exclusively" fullword ascii
		$v9 = "Mode:%d  Verbose:%d Daemon:%d AESNI:%d RDRAND:%d " fullword ascii
		$v10 = "pthread_cond_signal() error" fullword ascii
		$v11 = "ChaCha20 for x86_64, CRYPTOGAMS by <appro@openssl.org>" fullword ascii

	condition:
		( uint16( 0 ) == 0x457f and filesize < 200KB and ( 8 of them ) ) or ( all of them )
}

Strings (11 patterns)

IdentifierTypeValueModifiers
$v1text"esxcli vm process kill -t=force -w=%d"fullword ascii
$v2text"esxcli vm process kill -t=hard -w=%d"fullword ascii
$v3text"esxcli vm process kill -t=soft -w=%d"fullword ascii
$v4text"error encrypt: %s rename back:%s"fullword ascii
$v5text"esxcli vm process list"fullword ascii
$v6text"Total VM run on host:"fullword ascii
$v7text"error lock_exclusively:%s owner pid:%d"fullword ascii
$v8text"Error open %s in try_lock_exclusively"fullword ascii
$v9text"Mode:%d Verbose:%d Daemon:%d AESNI:%d RDRAND:%d "fullword ascii
$v10text"pthread_cond_signal() error"fullword ascii
$v11text"ChaCha20 for x86_64, CRYPTOGAMS by <appro@openssl.org>"fullword ascii

Condition

( uint16( 0 ) == 0x457f and filesize < 200KB and ( 8 of them ) ) or ( all of them )

In plain words (Heuristic)

  • The file must be smaller than 200KB (a cheap guard that skips large files).
  • All patterns in the rule must match.
  • At least 8 patterns in the rule 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).

  • ca607e431062ee49a21d69d722750e5edbd8ffabcb54fa92b231814101756041
  • 556e5cb5e4e77678110961c8d9260a726a363e00bf8d278e5302cb4bfccc3eed

Licence & attribution

Author: Christiaan @ ATR

Source repository: Trellix Advanced Research Center @ 1919562a59

Licence: Apache License 2.0 (repository licence)

Original rule

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

Rule id: 097b02e7-93d8-5d4f-9964-7b660b3cd7b9

Metadata

Rule_Versionv1
malware_typeransomware
malware_familyRansom:Linux/HelloKitty

Tags:RANSOMWAREFILE

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